497

Filed Pursuant to Rule 497(c)

1933 Act File No. 333-178987

1940 Act File No. 811-22653

SYMETRA MUTUAL FUNDS TRUST

On behalf of Symetra Mutual Funds Trust (the “Trust”) and pursuant to Rule 497(c) under the Securities Act of 1933, as amended, attached for filing are exhibits containing interactive data format risk/return summary information that mirrors the risk/return summary information in a definitive form of Prospectus, dated May 18, 2012, for each separate series of the Trust, which was filed pursuant to Rule 497(c) on June 4, 2012.  The purpose of this filing is to submit the 497(c) filing dated June 4, 2012 in XBRL for the Trust.

The XBRL exhibits attached hereto consist of the following:

Exhibit	Exhibit No.
Instance Document	EX-101.INS
Schema Document	EX-101.SCH
Calculation Linkbase Document	EX-101.CAL
Definition Linkbase Document	EX-101.DEF
Label Linkbase Document	EX-101.LAB
Presentation Linkbase Document	EX-101.PRE

XML

Symetra Pension Reserve Fund 2020 (b. 1953-1957) (Prospectus Summary) | Symetra Pension Reserve Fund 2020 (b. 1953-1957)

Symetra Pension Reserve Fund - 2020 (b.1953-1957)

Investment Objective

The Symetra Pension Reserve Fund - 2020 (1953-1957) (the "2020 (1953-1957) Fund"
or the "Fund") seeks investment returns that would provide an amount on the
Fund's termination date approximately equal to the then present value of
specified lifetime annuity payments to be made to investors born in the year
range identified in the Fund's name. As a result of its investment objective,
a Pension Reserve Fund may not be a wise investment choice for an investor who
does not anticipate applying his or her accumulation to the purchase of a
lifetime annuity on or shortly after the Fund's termination date.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the 2020 (1953-1957) Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity or variable life insurance contract level. If
those additional fees and expenses were included, overall expenses would be
higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra Pension Reserve Fund 2020 (b. 1953-1957)
Management Fees		0.32%
Other Expenses	[1]	1.77%
Total Annual Fund Operating Expenses		2.09%
Less: Fee Waiver and Expense Reimbursement	[2]	(1.69%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.40%

Example

This Example is intended to help you compare the cost of investing in the 2020
(1953-1957) Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated and
then redeem all of your shares at the end of those periods. The Example also
assumes that your investment has a 5% return each year and that the Fund's
operating expenses remain the same (taking into account the Expense Cap and Fee
Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra Pension Reserve Fund 2020 (b. 1953-1957)	41	491

Portfolio Turnover

The 2020 (1953-1957) Fund pays transaction costs, such as commissions, when it
buys and sells securities (or "turns over" its portfolio). A higher portfolio
turnover rate may indicate higher transaction costs and may result in higher
taxes when Fund shares are held in a taxable account. These costs, which are not
reflected in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Fund

The 2020 (1953-1957) Fund invests primarily in government securities and
dollar-denominated corporate debt securities rated, at the time of purchase,
in the three highest categories by an NRSRO or unrated securities that the
Sub-Adviser determines are of comparable quality. The Fund also may invest in
other types of dollar-denominated investment grade debt securities, including
money market instruments and securities of foreign issuers. Most of the
securities held by the Fund are zero coupon debt securities. Under normal market
conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring
government securities and dollar-denominated corporate debt securities rated, at
the time of purchase, in the two highest categories by an NRSRO, and investing
in other permitted investments when government securities and corporate
securities in the two highest categories are not available in sufficient
quantities at a reasonable price or are not available in optimal durations or
maturities.  The Fund also may manage portfolio duration by investing in
interest rate futures contracts, options on interest rate futures contracts,
structured notes and entering into swap agreements, provided that structured
notes and swap agreements are determined by the Sub-Adviser to pose minimal
counter-party credit risk.

The 2020 (1953-1957) Fund is managed to continuously meet portfolio duration
targets that correspond to projected payments, based on actuarially determined
survivorship rates, of a single life annuity on the life of a person born in the
year-range identified in the Fund's name. The portfolio duration targets are
recalculated at least monthly based on a formula established by the Adviser
(after consultation with Symetra Life Insurance Company ("Symetra Life")) at the
Fund's inception. The formula will not change once the Fund commences operations.
(The only variables in the formula are the amount of time remaining until each
annual projected payment of the single life annuity and the prevailing interest
rates on the recalculation date. The prevailing interest rates are derived from
the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under
normal market conditions, the Sub-Adviser seeks to meet the Fund's daily
portfolio duration target by first, to the extent that such investments are
available, investing in securities having cash flows similar to the projected
payments of the single life annuity and then by balancing investments in
securities with longer and shorter durations than the target duration. The
portfolio duration target generally declines for the Fund over the life of the
Fund, but will be substantially greater than zero at the Fund's termination
date. As a result, to meet the portfolio duration target, the Fund will likely
have an investment portfolio at its termination date of debt securities of
substantial remaining duration. This in turn, will result in the market value
of the Fund's investment portfolio at the termination date being significantly
influenced by prevailing interest rates. Generally speaking, the higher the
prevailing rates at the Fund's maturity, the less the Fund will receive from
selling its assets and the lower the prevailing rates, the more the Fund will
receive for selling its assets. Thus, the market value of such assets is
inversely related to prevailing interest rates.

The present value of a future series of payments decreases as the interest rate
on which the present value is computed increases. Therefore, on the 2020
(1953-1957) Fund's termination date the present value of the annuity payments
the investor is entitled to receive as a result of owning accumulation units in
the sub-account of the Symetra Resource Variable Account B that invests in
shares of the Fund will be less the higher the prevailing interest rates. The
Fund's adherence to the portfolio duration target formula is intended to result
in the Fund having on its termination date net assets approximately equal to the
present value of the aggregate annuity payments investors are entitled to
receive as a result of owning accumulation units in the sub-account of the
Symetra Resource Variable Account B that invests in shares of the Fund. However,
even if a Fund successfully adheres to the formula, there is no guarantee that
it will achieve this intended result or its investment objective. Although the
Fund has no current plans to close, there is no guarantee that the Fund will
continue to accept new investments until the termination date.

As of the date of this Prospectus, based on the current U.S. Treasury Zero
Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2020
(1953-1957) Fund's portfolio duration target would have been 19.5 years.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the 2020
(1953-1957) Fund. The following additional risks could affect the value of your
investment:

· Credit Risk. The issuers of the bonds and other debt securities held by the    
  2020 (1953-1957) Fund may not be able to make interest or principal payments   
  when due. Even if these issuers are able to make interest or principal         
  payments, changes in an issuer's credit rating or the market's perception of an
  issuer's creditworthiness may also affect the value of the Fund's investment in
  that issuer by leading to greater volatility in the price of the security.     
  
· Credit Default Swap Risk. In a credit default swap transaction, both the 2020
  (1953-1957) Fund and its counter-party are exposed to the risk of default by   
  the other. In addition, the terms of most credit default swap transactions     
  require little or no initial investment by the seller in relation to the       
  notional amount of the swap and the corresponding risk. Therefore, small       
  changes in the market value of the reference security or group of securities   
  may produce disproportionate and substantial losses for the seller.            

· Derivatives Risk. Derivatives are securities, such as futures contracts, whose
  value is derived from that of other securities or indices. The 2020 (1953-1957)
  Fund's investments in derivatives may pose risks in addition to those          
  associated with investing directly in securities or other investments.         
  Derivative securities are subject to a number of risks including liquidity,    
  interest rate, market, credit and management risks, the risk of improper       
  valuation, illiquidity of the derivatives, imperfect correlations with         
  underlying investments or the Fund's other portfolio holdings, lack of         
  availability and counterparty risk. Changes in the value of the derivative may
  not correlate perfectly with the underlying asset, rate or index, and the Fund
  could lose more than the principal amount invested. An investment in           
  derivatives may not perform as anticipated by the Sub-Adviser, may not be able
  to be closed out at a favorable time or price. An investment in derivatives may
  also increase the Fund's volatility and create investment leverage. When a     
  derivative is used as a substitute or alternative to a direct cash investment,
  the transaction may not provide a return that corresponds precisely with that  
  of the cash investment; or, when used for hedging purposes, derivatives may not
  provide the anticipated protection, causing the Fund to lose money on both the
  derivatives transaction and the exposure the Fund sought to hedge.             

· Extension Risk. When interest rates rise, certain obligations will be paid off
  by the obligor more slowly than anticipated, causing the value of these        
  securities to fall.                                                            

· Foreign Investing Risk. The securities of foreign issuers may be less liquid   
  and more volatile than securities of comparable U.S. issuers. Investments in   
  securities of foreign issuers, even those publicly traded in the United States,
  may involve risks which are in addition to those inherent in domestic          
  investments. Foreign companies may not be subject to the same regulatory       
  requirements of U.S. companies, and as a consequence, there may be less        
  publicly available information about such companies. Also, foreign companies   
  may not be subject to uniform accounting, auditing, and financial reporting    
  standards and requirements comparable to those applicable to U.S. companies.   
  Foreign governments and foreign economies often are less stable than the U.S.  
  Government and the U.S. economy.                                               

· Interest Rate Risk. In general, the value of bonds and other debt securities   
  falls when interest rates rise. Generally, the longer the duration of a debt   
  security, the greater is the negative effect on its value when rates           
  increase. Because zero coupon debt securities do not pay interest, the market  
  value of such securities can fall more dramatically than interest-paying       
  securities of similar maturities when interest rates rise. While bonds and     
  other debt securities normally fluctuate less in price than common stocks,     
  there have been extended periods of increases in interest rates that have      
  caused significant declines in bond prices.                                    

· Management Risk. The 2020 (1953-1957) Fund is subject to management risk       
  because it is an actively managed portfolio. The portfolio manager's management
  practices, investment strategies, and choice of investments might not work to  
  produce the desired results and the Fund might underperform other comparable   
  funds.                                                                         

· Market Risk. The prices of the securities in which the 2020 (1953-1957) Fund   
  invests may decline for a number of reasons including in response to economic  
  developments and perceptions about the creditworthiness of individual          
  issuers. Longer-term bonds, in which the Fund will invest a majority of its    
  assets, are generally more volatile.                                           

· New Fund Risk. The 2020 (1953-1957) Fund is new with no operating history and  
  there can be no assurance that the Fund will grow to or maintain an            
  economically viable size. If the Fund does not grow to or maintain an          
  economically viable size the Board may consider various alternatives, including
  the liquidation of the Fund or the merger of the Fund into another mutual fund.
  
· Portfolio Duration Target Formula Risk. There is no guarantee that adherence to
  the portfolio duration target formula will result in the Fund achieving its    
  investment objective.                                                          

· Prepayment Risk. When interest rates fall, certain obligations will be paid off
  by the obligor more quickly than originally anticipated, and the 2020          
  (1953-1957) Fund may have to invest the proceeds in securities with lower      
  yields (this is known as Reinvestment Risk).                                   

· Termination Risk. Because the 2020 (1953-1957) Fund has a Termination Date and
  it will invest a majority of its assets in securities that mature after the    
  Termination Date, the Fund may incur liquidation costs to liquidate its        
  portfolio.                                                                     

· U.S. Government Issuer Risk. Treasury obligations may differ in their interest
  rates, maturities, times of issuance and other characteristics. Obligations of
  U.S. Government agencies and authorities are supported by varying degrees of   
  credit but generally are not backed by the full faith and credit of the U.S.   
  Government. No assurance can be given that the U.S. Government will provide    
  financial support to its agencies and authorities if it is not obligated by law
  to do so.

Performance

When the 2020 (1953-1957) Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2020 (b.1953-1957) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Symetra Pension Reserve Fund 2024 (b. 1958-1962) (Prospectus Summary) | Symetra Pension Reserve Fund 2024 (b. 1958-1962)

Symetra Pension Reserve Fund - 2024 (b.1958-1962)

Investment Objective

The Symetra Pension Reserve Fund - 2024 (b.1958-1962) (the "2024 (1958-1962)
Fund" or the "Fund") seeks investment returns that would provide an amount on
the Fund's termination date approximately equal to the then present value of
specified lifetime annuity payments to be made to investors born in the year
range identified in the Fund's name. As a result of its investment objective,
a Pension Reserve Fund may not be a wise investment choice for an investor
who does not anticipate applying his or her accumulation to the purchase of a
lifetime annuity on or shortly after the Fund's termination date.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the 2024 (1958-1962) Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity or variable life insurance contract level. If
those additional fees and expenses were included, overall expenses would be
higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra Pension Reserve Fund 2024 (b. 1958-1962)
Management Fees		0.32%
Other Expenses	[1]	1.77%
Total Annual Fund Operating Expenses		2.09%
Less: Fee Waiver and Expense Reimbursement	[2]	(1.69%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.40%

Example

This Example is intended to help you compare the cost of investing in the 2024
(1958-1962) Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated and
then redeem all of your shares at the end of those periods. The Example also
assumes that your investment has a 5% return each year and that the Fund's
operating expenses remain the same (taking into account the Expense Cap and Fee
Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra Pension Reserve Fund 2024 (b. 1958-1962)	41	491

Portfolio Turnover

The 2024 (1958-1962) Fund pays transaction costs, such as commissions, when it
buys and sells securities (or "turns over" its portfolio). A higher portfolio
turnover rate may indicate higher transaction costs and may result in higher
taxes when Fund shares are held in a taxable account. These costs, which are not
reflected in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Fund

The 2024 (1958-1962) Fund invests primarily in government securities and
dollar-denominated corporate debt securities rated, at the time of purchase, in
the three highest categories by an NRSRO or unrated securities that the
Sub-Adviser determines are of comparable quality. The Fund also may invest in
other types of dollar-denominated investment grade debt securities, including
money market instruments and securities of foreign issuers. Most of the
securities held by the Fund are zero coupon debt securities. Under normal market
conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring
government securities and dollar-denominated corporate debt securities rated, at
the time of purchase, in the two highest categories by an NRSRO, and investing
in other permitted investments when government securities and corporate
securities in the two highest categories are not available in sufficient
quantities at a reasonable price or are not available in optimal durations or
maturities.  The Fund also may manage portfolio duration by investing in
interest rate futures contracts, options on interest rate futures contracts,
structured notes and entering into swap agreements, provided that structured
notes and swap agreements are determined by the Sub-Adviser to pose minimal
counter-party credit risk.

The 2024 (1958-1962) Fund is managed to continuously meet portfolio duration
targets that correspond to projected payments, based on actuarially determined
survivorship rates, of a single life annuity on the life of a person born in the
year-range identified in the Fund's name. The portfolio duration targets are
recalculated at least monthly based on a formula established by the Adviser
(after consultation with Symetra Life Insurance Company ("Symetra Life")) at the
Fund's inception. The formula will not change once the Fund commences operations.
(The only variables in the formula are the amount of time remaining until each
annual projected payment of the single life annuity and the prevailing interest
rates on the recalculation date. The prevailing interest rates are derived from
the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under
normal market conditions, the Sub-Adviser seeks to meet the Fund's daily
portfolio duration target by first, to the extent that such investments are
available, investing in securities having cash flows similar to the projected
payments of the single life annuity and then by balancing investments in
securities with longer and shorter durations than the target duration. The
portfolio duration target generally declines for the Fund over the life of the
Fund, but will be substantially greater than zero at the Fund's termination
date. As a result, to meet the portfolio duration target, the Fund will likely
have an investment portfolio at its termination date of debt securities of
substantial remaining duration. This in turn, will result in the market value
of the Fund's investment portfolio at the termination date being significantly
influenced by prevailing interest rates. Generally speaking, the higher the
prevailing rates at the Fund's maturity, the less the Fund will receive from
selling its assets and the lower the prevailing rates, the more the Fund will
receive for selling its assets. Thus, the market value of such assets is
inversely related to prevailing interest rates.

The present value of a future series of payments decreases as the interest rate
on which the present value is computed increases. Therefore, on the 2024
(1958-1962) Fund's termination date the present value of the annuity payments
the investor is entitled to receive as a result of owning accumulation units in
the sub-account of the Symetra Resource Variable Account B that invests in
shares of the Fund will be less the higher the prevailing interest rates. The
Fund's adherence to the portfolio duration target portfolio is intended to
result in the Fund having on its termination date net assets approximately equal
to the present value of the aggregate annuity payments investors are entitled to
receive as a result of owning accumulation units in the sub-account of the
Symetra Resource Variable Account B that invests in shares of the Fund. However,
even if a Fund successfully adheres to the formula, there is no guarantee that
it will achieve this intended result or its investment objective. Although the
Fund has no current plans to close, there is no guarantee that the Fund will
continue to accept new investments until the termination date.

As of the date of this Prospectus, based on the current U.S. Treasury Zero
Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2024
(1958-1962) Fund's portfolio duration target would have been 23.4 years.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the 2024
(1958-1962) Fund. The following additional risks could affect the value of your
investment:

· Credit Risk. The issuers of the bonds and other debt securities held by the    
  2024 (1958-1962) Fund may not be able to make interest or principal payments   
  when due. Even if these issuers are able to make interest or principal         
  payments, changes in an issuer's credit rating or the market's perception of
  an issuer's creditworthiness may also affect the value of the Fund's investment
  in that issuer by leading to greater volatility in the price of the security.     
  
· Credit Default Swap Risk. In a credit default swap transaction, both the 2024
  (1958-1962) Fund and its counter-party are exposed to the risk of default by   
  the other. In addition, the terms of most credit default swap transactions     
  require little or no initial investment by the seller in relation to the       
  notional amount of the swap and the corresponding risk. Therefore, small       
  changes in the market value of the reference security or group of securities   
  may produce disproportionate and substantial losses for the seller.            

· Derivatives Risk. Derivatives are securities, such as futures contracts, whose
  value is derived from that of other securities or indices. The 2024 (1958-1962)
  Fund's investments in derivatives may pose risks in addition to those          
  associated with investing directly in securities or other investments.         
  Derivative securities are subject to a number of risks including liquidity,    
  interest rate, market, credit and management risks, the risk of improper       
  valuation, illiquidity of the derivatives, imperfect correlations with         
  underlying investments or the Fund's other portfolio holdings, lack of         
  availability and counterparty risk. Changes in the value of the derivative may
  not correlate perfectly with the underlying asset, rate or index, and the Fund
  could lose more than the principal amount invested. An investment in           
  derivatives may not perform as anticipated by the Sub-Adviser, may not be able
  to be closed out at a favorable time or price. An investment in derivatives may
  also increase the Fund's volatility and create investment leverage. When a     
  derivative is used as a substitute or alternative to a direct cash investment,
  the transaction may not provide a return that corresponds precisely with that  
  of the cash investment; or, when used for hedging purposes, derivatives may not
  provide the anticipated protection, causing the Fund to lose money on both the
  derivatives transaction and the exposure the Fund sought to hedge.             

· Extension Risk. When interest rates rise, certain obligations will be paid off
  by the obligor more slowly than anticipated, causing the value of these        
  securities to fall.                                                            

· Foreign Investing Risk. The securities of foreign issuers may be less liquid   
  and more volatile than securities of comparable U.S. issuers. Investments in   
  securities of foreign issuers, even those publicly traded in the United States,
  may involve risks which are in addition to those inherent in domestic          
  investments. Foreign companies may not be subject to the same regulatory       
  requirements of U.S. companies, and as a consequence, there may be less        
  publicly available information about such companies. Also, foreign companies   
  may not be subject to uniform accounting, auditing, and financial reporting    
  standards and requirements comparable to those applicable to U.S. companies.   
  Foreign governments and foreign economies often are less stable than the U.S.  
  Government and the U.S. economy.                                               

· Interest Rate Risk. In general, the value of bonds and other debt securities   
  falls when interest rates rise. Generally, the longer the duration of a debt   
  security, the greater is the negative effect on its value when rates           
  increase. Because zero coupon debt securities do not pay interest, the market  
  value of such securities can fall more dramatically than interest-paying       
  securities of similar maturities when interest rates rise. While bonds and     
  other debt securities normally fluctuate less in price than common stocks,     
  there have been extended periods of increases in interest rates that have      
  caused significant declines in bond prices.                                    

· Management Risk. The 2024 (1958-1962) Fund is subject to management risk       
  because it is an actively managed portfolio. The portfolio manager's management
  practices, investment strategies, and choice of investments might not work to  
  produce the desired results and the Fund might underperform other comparable   
  funds.                                                                         

· Market Risk. The prices of the securities in which the 2024 (1958-1962) Fund   
  invests may decline for a number of reasons including in response to economic  
  developments and perceptions about the creditworthiness of individual          
  issuers. Longer-term bonds, in which the Fund will invest a majority of its    
  assets, are generally more volatile.                                           

· New Fund Risk. The 2024 (1958-1962) Fund is new with no operating history and  
  there can be no assurance that the Fund will grow to or maintain an            
  economically viable size. If the Fund does not grow to or maintain an          
  economically viable size the Board may consider various alternatives, including
  the liquidation of the Fund or the merger of the Fund into another mutual fund.
  
· Portfolio Duration Target Formula Risk. There is no guarantee that adherence to
  the portfolio duration target formula will result in the Fund achieving its    
  investment objective.                                                          

· Prepayment Risk. When interest rates fall, certain obligations will be paid off
  by the obligor more quickly than originally anticipated, and the 2024          
  (1958-1962) Fund may have to invest the proceeds in securities with lower      
  yields (this is known as Reinvestment Risk).                                   

· Termination Risk. Because the 2024 (1958-1962) Fund has a Termination Date and
  it will invest a majority of its assets in securities that mature after the    
  Termination Date, the Fund may incur liquidation costs to liquidate its        
  portfolio.                                                                     

· U.S. Government Issuer Risk. Treasury obligations may differ in their interest
  rates, maturities, times of issuance and other characteristics. Obligations of
  U.S. Government agencies and authorities are supported by varying degrees of   
  credit but generally are not backed by the full faith and credit of the U.S.   
  Government. No assurance can be given that the U.S. Government will provide    
  financial support to its agencies and authorities if it is not obligated by law
  to do so.

Performance

When the 2024 (1958-1962) Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2024 (b.1958-1962 (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Symetra Pension Reserve Fund 2028 (b. 1948-1952) (Prospectus Summary) | Symetra Pension Reserve Fund 2028 (b. 1948-1952)

Symetra Pension Reserve Fund - 2028 (b.1948-1952)

Investment Objective

The Symetra Pension Reserve Fund - 2028 (b.1948-1952) (the "2028 (1948-1952)
Fund" or the "Fund") seeks investment returns that would provide an amount on
the Fund's termination date approximately equal to the then present value of
specified lifetime annuity payments to be made to investors born in the year
range identified in the Fund's name. As a result of its investment objective,
a Pension Reserve Fund may not be a wise investment choice for an investor who
does not anticipate applying his or her accumulation to the purchase of a
lifetime annuity on or shortly after the Fund's termination date.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the 2028 (1948-1952) Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity or variable life insurance contract level. If
those additional fees and expenses were included, overall expenses would be
higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra Pension Reserve Fund 2028 (b. 1948-1952)
Management Fees		0.32%
Other Expenses	[1]	1.77%
Total Annual Fund Operating Expenses		2.09%
Less: Fee Waiver and Expense Reimbursement	[2]	(1.69%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.40%

Example

This Example is intended to help you compare the cost of investing in the 2028
(1948-1952) Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated and
then redeem all of your shares at the end of those periods. The Example also
assumes that your investment has a 5% return each year and that the Fund's
operating expenses remain the same (taking into account the Expense Cap and Fee
Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra Pension Reserve Fund 2028 (b. 1948-1952)	41	491

Portfolio Turnover

The 2028 (1948-1952) Fund pays transaction costs, such as commissions, when it
buys and sells securities (or "turns over" its portfolio). A higher portfolio
turnover rate may indicate higher transaction costs and may result in higher
taxes when Fund shares are held in a taxable account. These costs, which are not
reflected in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Fund

The 2028 (1948-1952) Fund invests primarily in government securities and
dollar-denominated corporate debt securities rated, at the time of purchase,
in the three highest categories by an NRSRO or unrated securities that the
Sub-Adviser determines are of comparable quality. The Fund also may invest in
other types of dollar-denominated investment grade debt securities, including
money market instruments and securities of foreign issuers. Most of the
securities held by the Fund are zero coupon debt securities. Under normal market
conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring
government securities and dollar-denominated corporate debt securities rated, at
the time of purchase, in the two highest categories by an NRSRO, and investing
in other permitted investments when government securities and corporate
securities in the two highest categories are not available in sufficient
quantities at a reasonable price or are not available in optimal durations or
maturities.  The Fund also may manage portfolio duration by investing in
interest rate futures contracts, options on interest rate futures contracts,
structured notes and entering into swap agreements, provided that structured
notes and swap agreements are determined by the Sub-Adviser to pose minimal
counter-party credit risk.

The 2028 (1948-1952) Fund is managed to continuously meet portfolio duration
targets that correspond to projected payments, based on actuarially determined
survivorship rates, of a single life annuity on the life of a person born in the
year-range identified in the Fund's name. The portfolio duration targets are
recalculated at least monthly based on a formula established by the Adviser
(after consultation with Symetra Life Insurance Company ("Symetra Life")) at the
Fund's inception. The formula will not change once the Fund commences
operations. (The only variables in the formula are the amount of time remaining
until each annual projected payment of the single life annuity and the
prevailing interest rates on the recalculation date. The prevailing interest
rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by
interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet
the Fund's daily portfolio duration target by first, to the extent that such
investments are available, investing in securities having cash flows similar to
the projected payments of the single life annuity and then by balancing
investments in securities with longer and shorter durations than the target
duration. The portfolio duration target generally declines for the Fund over the
life of the Fund, but will be substantially greater than zero at the Fund's
termination date. As a result, to meet the portfolio duration target, the Fund
will likely have an investment portfolio at its termination date of debt
securities of substantial remaining duration. This in turn, will result in the
market value of the Fund's investment portfolio at the termination date being
significantly influenced by prevailing interest rates. Generally speaking, the
higher the prevailing rates at the Fund's maturity, the less the Fund will
receive from selling its assets and the lower the prevailing rates, the more the
Fund will receive for selling its assets. Thus, the market value of such assets
is inversely related to prevailing interest rates.

The present value of a future series of payments decreases as the interest rate
on which the present value is computed increases. Therefore, on the 2028
(1948-1952) Fund's termination date the present value of the annuity payments
the investor is entitled to receive as a result of owning accumulation units in
the sub-account of the Symetra Resource Variable Account B that invests in
shares of the Fund will be less the higher the prevailing interest rates. The
Fund's adherence to the portfolio duration target formula is intended to result
in the Fund having on its termination date net assets approximately equal to the
present value of the aggregate annuity payments investors are entitled to
receive as a result of owning accumulation units in the sub-account of the
Symetra Resource Variable Account B that invests in shares of the Fund. However,
even if a Fund successfully adheres to the formula, there is no guarantee that
it will achieve this intended result or its investment objective. Although the
Fund has no current plans to close, there is no guarantee that the Fund will
continue to accept new investments until the termination date.

As of the date of this Prospectus, based on the current U.S. Treasury Zero
Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2028
(1948-1952) Fund's portfolio duration target would have been 22.3 years.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the 2028
(1948-1952) Fund. The following additional risks could affect the value of your
investment:

· Credit Risk. The issuers of the bonds and other debt securities held by the    
  2028 (1948-1952) Fund may not be able to make interest or principal payments   
  when due. Even if these issuers are able to make interest or principal         
  payments, changes in an issuer's credit rating or the market's perception of an
  issuer's creditworthiness may also affect the value of the Fund's investment in
  that issuer by leading to greater volatility in the price of the security.     

· Credit Default Swap Risk. In a credit default swap transaction, both the 2028
  (1948-1952) Fund and its counter-party are exposed to the risk of default by   
  the other. In addition, the terms of most credit default swap transactions     
  require little or no initial investment by the seller in relation to the       
  notional amount of the swap and the corresponding risk. Therefore, small       
  changes in the market value of the reference security or group of securities   
  may produce disproportionate and substantial losses for the seller.            
  
· Derivatives Risk. Derivatives are securities, such as futures contracts, whose
  value is derived from that of other securities or indices. The 2028 (1948-1952)
  Fund's investments in derivatives may pose risks in addition to those          
  associated with investing directly in securities or other investments.         
  Derivative securities are subject to a number of risks including liquidity,    
  interest rate, market, credit and management risks, the risk of improper       
  valuation, illiquidity of the derivatives, imperfect correlations with         
  underlying investments or the Fund's other portfolio holdings, lack of         
  availability and counterparty risk. Changes in the value of the derivative may
  not correlate perfectly with the underlying asset, rate or index, and the Fund
  could lose more than the principal amount invested. An investment in           
  derivatives may not perform as anticipated by the Sub-Adviser, may not be able
  to be closed out at a favorable time or price. An investment in derivatives may
  also increase the Fund's volatility and create investment leverage. When a     
  derivative is used as a substitute or alternative to a direct cash investment,
  the transaction may not provide a return that corresponds precisely with that  
  of the cash investment; or, when used for hedging purposes, derivatives may not
  provide the anticipated protection, causing the Fund to lose money on both the
  derivatives transaction and the exposure the Fund sought to hedge.             

· Extension Risk. When interest rates rise, certain obligations will be paid off
  by the obligor more slowly than anticipated, causing the value of these        
  securities to fall.                                                            

· Foreign Investing Risk. The securities of foreign issuers may be less liquid   
  and more volatile than securities of comparable U.S. issuers. Investments in   
  securities of foreign issuers, even those publicly traded in the United States,
  may involve risks which are in addition to those inherent in domestic          
  investments. Foreign companies may not be subject to the same regulatory       
  requirements of U.S. companies, and as a consequence, there may be less        
  publicly available information about such companies. Also, foreign companies   
  may not be subject to uniform accounting, auditing, and financial reporting    
  standards and requirements comparable to those applicable to U.S. companies.   
  Foreign governments and foreign economies often are less stable than the U.S.  
  Government and the U.S. economy.                                               
  
· Interest Rate Risk. In general, the value of bonds and other debt securities   
  falls when interest rates rise. Generally, the longer the duration of a debt   
  security, the greater is the negative effect on its value when rates           
  increase. Because zero coupon debt securities do not pay interest, the market  
  value of such securities can fall more dramatically than interest-paying       
  securities of similar maturities when interest rates rise. While bonds and     
  other debt securities normally fluctuate less in price than common stocks,     
  there have been extended periods of increases in interest rates that have      
  caused significant declines in bond prices.                                    
  
· Management Risk. The 2028 (1948-1952) Fund is subject to management risk       
  because it is an actively managed portfolio. The portfolio manager's management
  practices, investment strategies, and choice of investments might not work to  
  produce the desired results and the Fund might underperform other comparable   
  funds.                                                                         
  
· Market Risk. The prices of the securities in which the 2028 (1948-1952) Fund   
  invests may decline for a number of reasons including in response to economic  
  developments and perceptions about the creditworthiness of individual          
  issuers. Longer-term bonds, in which the Fund will invest a majority of its    
  assets, are generally more volatile.                                           
  
· New Fund Risk. The 2028 (1948-1952) Fund is new with no operating history and  
  there can be no assurance that the Fund will grow to or maintain an            
  economically viable size. If the Fund does not grow to or maintain an          
  economically viable size the Board may consider various alternatives, including
  the liquidation of the Fund or the merger of the Fund into another mutual fund.

· Portfolio Duration Target Formula Risk. There is no guarantee that adherence to
  the portfolio duration target formula will result in the Fund achieving its    
  investment objective.                                                          
  
· Prepayment Risk. When interest rates fall, certain obligations will be paid off
  by the obligor more quickly than originally anticipated, and the 2028          
  (1948-1952) Fund may have to invest the proceeds in securities with lower      
  yields (this is known as Reinvestment Risk).                                   

· Termination Risk. Because the 2028 (1948-1952) Fund has a Termination Date and
  it will invest a majority of its assets in securities that mature after the    
  Termination Date, the Fund may incur liquidation costs to liquidate its        
  portfolio.                                                                     
  
· U.S. Government Issuer Risk. Treasury obligations may differ in their interest
  rates, maturities, times of issuance and other characteristics. Obligations of
  U.S. Government agencies and authorities are supported by varying degrees of   
  credit but generally are not backed by the full faith and credit of the U.S.   
  Government. No assurance can be given that the U.S. Government will provide    
  financial support to its agencies and authorities if it is not obligated by law
  to do so.

Performance

When the 2028 (1948-1952) Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2028 (b.1948-1952) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra Pension Reserve Fund 2024 (b. 1942-1947) (Prospectus Summary) | Symetra Pension Reserve Fund 2024 (b. 1942-1947)
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra Pension Reserve Fund - 2024 (b.1942-1947)
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra Pension Reserve Fund - 2024 (b.1942-1947) (the "2024 (1942-1947) Fund" or the "Fund") seeks investment returns that would provide an amount on the Fund's termination date approximately equal to the then present value of specified lifetime annuity payments to be made to investors born in the year range identified in the Fund's name. As a result of its investment objective, a Pension Reserve Fund may not be a wise investment choice for an investor who does not anticipate applying his or her accumulation to the purchase of a lifetime annuity on or shortly after the Fund's termination date.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the 2024 (1942-1947) Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The 2024 (1942-1947) Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" is an estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the 2024 (1942-1947) Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The 2024 (1942-1947) Fund invests primarily in government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the three highest categories by an NRSRO or unrated securities that the Sub-Adviser determines are of comparable quality. The Fund also may invest in other types of dollar-denominated investment grade debt securities, including money market instruments and securities of foreign issuers. Most of the securities held by the Fund are zero coupon debt securities. Under normal market conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the two highest categories by an NRSRO, and investing in other permitted investments when government securities and corporate securities in the two highest categories are not available in sufficient quantities at a reasonable price or are not available in optimal durations or maturities.  The Fund also may manage portfolio duration by investing in interest rate futures contracts, options on interest rate futures contracts, structured notes and entering into swap agreements, provided that structured notes and swap agreements are determined by the Sub-Adviser to pose minimal counter-party credit risk. The 2024 (1942-1947) Fund is managed to continuously meet portfolio duration targets that correspond to projected payments, based on actuarially determined survivorship rates, of a single life annuity on the life of a person born in the year-range identified in the Fund's name. The portfolio duration targets are recalculated at least monthly based on a formula established by the Adviser (after consultation with Symetra Life Insurance Company ("Symetra Life")) at the Fund's inception. The formula will not change once the Fund commences operations. (The only variables in the formula are the amount of time remaining until each annual projected payment of the single life annuity and the prevailing interest rates on the recalculation date. The prevailing interest rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet the Fund's daily portfolio duration target by first, to the extent that such investments are available, investing in securities having cash flows similar to the projected payments of the single life annuity and then by balancing investments in securities with longer and shorter durations than the target duration. The portfolio duration target generally declines for the Fund over the life of the Fund, but will be substantially greater than zero at the Fund's termination date. As a result, to meet the portfolio duration target, the Fund will likely have an investment portfolio at its termination date of debt securities of substantial remaining duration. This in turn, will result in the market value of the Fund's investment portfolio at the termination date being significantly influenced by prevailing interest rates. Generally speaking, the higher the prevailing rates at the Fund's maturity, the less the Fund will receive from selling its assets and the lower the prevailing rates, the more the Fund will receive for selling its assets. Thus, the market value of such assets is inversely related to prevailing interest rates. The present value of a future series of payments decreases as the interest rate on which the present value is computed increases. Therefore, on the 2024 (1942-1947) Fund's termination date the present value of the annuity payments the investor is entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund will be less the higher the prevailing interest rates. The Fund's adherence to the portfolio duration target formula is intended to result in the Fund having on its termination date net assets approximately equal to the present value of the aggregate annuity payments investors are entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund. However, even if a Fund successfully adheres to the formula, there is no guarantee that it will achieve this intended result or its investment objective. Although the Fund has no current plans to close, there is no guarantee that the Fund will continue to accept new investments until the termination date. As of the date of this Prospectus, based on the current U.S. Treasury Zero Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2024 (1942-1947) Fund's portfolio duration target would have been 18.5 years.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the 2024 (1942-1947) Fund. The following additional risks could affect the value of your investment: · Credit Risk. The issuers of the bonds and other debt securities held by the       2024 (1942-1947) Fund may not be able to make interest or principal payments      when due. Even if these issuers are able to make interest or principal            payments, changes in an issuer's credit rating or the market's perception of an   issuer's creditworthiness may also affect the value of the Fund's investment in   that issuer by leading to greater volatility in the price of the security.      · Credit Default Swap Risk.  In a credit default swap transaction, both the 2024   (1942-1947) Fund and its counter-party are exposed to the risk of default by      the other. In addition, the terms of most credit default swap transactions        require little or no initial investment by the seller in relation to the          notional amount of the swap and the corresponding risk. Therefore, small          changes in the market value of the reference security or group of securities      may produce disproportionate and substantial losses for the seller.                · Derivatives Risk. Derivatives are securities, such as futures contracts, whose   value is derived from that of other securities or indices. The Fund's             investments in derivatives may pose risks in addition to those associated with   investing directly in securities or other investments. Derivative securities      are subject to a number of risks including liquidity, interest rate, market,      credit and management risks, the risk of improper valuation, illiquidity of the   derivatives, imperfect correlations with underlying investments or the Fund's     other portfolio holdings, lack of availability and counterparty risk. Changes     in the value of the derivative may not correlate perfectly with the underlying   asset, rate or index, and the Fund could lose more than the principal amount      invested. An investment in derivatives may not perform as anticipated by the      Sub-Adviser, may not be able to be closed out at a favorable time or price. An   investment in derivatives may also increase the Fund's volatility and create      investment leverage. When a derivative is used as a substitute or alternative     to a direct cash investment, the transaction may not provide a return that        corresponds precisely with that of the cash investment; or, when used for         hedging purposes, derivatives may not provide the anticipated protection,         causing the Fund to lose money on both the derivatives transaction and the        exposure the Fund sought to hedge.                                                 · Extension Risk. When interest rates rise, certain obligations will be paid off   by the obligor more slowly than anticipated, causing the value of these           securities to fall.                                                                · Foreign Investing Risk. The securities of foreign issuers may be less liquid      and more volatile than securities of comparable U.S. issuers. Investments in      securities of foreign issuers, even those publicly traded in the United States,   may involve risks which are in addition to those inherent in domestic             investments. Foreign companies may not be subject to the same regulatory          requirements of U.S. companies, and as a consequence, there may be less           publicly available information about such companies. Also, foreign companies      may not be subject to uniform accounting, auditing, and financial reporting       standards and requirements comparable to those applicable to U.S. companies.      Foreign governments and foreign economies often are less stable than the U.S.     Government and the U.S. economy.                                                   · Interest Rate Risk. In general, the value of bonds and other debt securities      falls when interest rates rise. Generally, the longer the duration of a debt      security, the greater is the negative effect on its value when rates              increase. Because zero coupon debt securities do not pay interest, the market     value of such securities can fall more dramatically than interest-paying          securities of similar maturities when interest rates rise. While bonds and        other debt securities normally fluctuate less in price than common stocks,        there have been extended periods of increases in interest rates that have         caused significant declines in bond prices.                                        · Management Risk. The 2024 (1942-1947) Fund is subject to management risk          because it is an actively managed portfolio. The portfolio manager's management   practices, investment strategies, and choice of investments might not work to     produce the desired results and the Fund might underperform other comparable      funds.                                                                             · Market Risk. The prices of the securities in which the 2024 (1942-1947) Fund      invests may decline for a number of reasons including in response to economic     developments and perceptions about the creditworthiness of individual             issuers. Longer-term bonds, in which the Fund will invest a majority of its       assets, are generally more volatile.                                               · New Fund Risk. The 2024 (1942-1947) Fund is new with no operating history and     there can be no assurance that the Fund will grow to or maintain an               economically viable size. If the Fund does not grow to or maintain an             economically viable size the Board may consider various alternatives, including   the liquidation of the Fund or the merger of the Fund into another mutual fund. · Portfolio Duration Target Formula Risk. There is no guarantee that adherence to   the portfolio duration target formula will result in the Fund achieving its       investment objective.                                                              · Prepayment Risk. When interest rates fall, certain obligations will be paid off   by the obligor more quickly than originally anticipated, and the 2024             (1942-1947) Fund may have to invest the proceeds in securities with lower         yields (this is known as Reinvestment Risk).                                       · Termination Risk. Because the 2024 (1942-1947) Fund has a Termination Date and   it will invest a majority of its assets in securities that mature after the       Termination Date, the Fund may incur liquidation costs to liquidate its           portfolio.                                                                         · U.S. Government Issuer Risk. Treasury obligations may differ in their interest   rates, maturities, times of issuance and other characteristics. Obligations of   U.S. Government agencies and authorities are supported by varying degrees of      credit but generally are not backed by the full faith and credit of the U.S.      Government. No assurance can be given that the U.S. Government will provide       financial support to its agencies and authorities if it is not obligated by law   to do so.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the 2024 (1942-1947) Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the 2024 (1942-1947) Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the 2024 (1942-1947) Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-SYMETRA (1-800-796-3872)
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra Pension Reserve Fund 2024 (b. 1942-1947) (Prospectus Summary) | Symetra Pension Reserve Fund 2024 (b. 1942-1947) | Symetra Pension Reserve Fund 2024 (b. 1942-1947)
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.32%
Other Expenses	rr_OtherExpensesOverAssets	1.77%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.09%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.69%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.40%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	41
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	491

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2024 (b.1942-1947) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra Pension Reserve Fund 2024 (b. 1958-1962) (Prospectus Summary) | Symetra Pension Reserve Fund 2024 (b. 1958-1962)
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra Pension Reserve Fund - 2024 (b.1958-1962)
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra Pension Reserve Fund - 2024 (b.1958-1962) (the "2024 (1958-1962) Fund" or the "Fund") seeks investment returns that would provide an amount on the Fund's termination date approximately equal to the then present value of specified lifetime annuity payments to be made to investors born in the year range identified in the Fund's name. As a result of its investment objective, a Pension Reserve Fund may not be a wise investment choice for an investor who does not anticipate applying his or her accumulation to the purchase of a lifetime annuity on or shortly after the Fund's termination date.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the 2024 (1958-1962) Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The 2024 (1958-1962) Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" is an estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the 2024 (1958-1962) Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The 2024 (1958-1962) Fund invests primarily in government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the three highest categories by an NRSRO or unrated securities that the Sub-Adviser determines are of comparable quality. The Fund also may invest in other types of dollar-denominated investment grade debt securities, including money market instruments and securities of foreign issuers. Most of the securities held by the Fund are zero coupon debt securities. Under normal market conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the two highest categories by an NRSRO, and investing in other permitted investments when government securities and corporate securities in the two highest categories are not available in sufficient quantities at a reasonable price or are not available in optimal durations or maturities.  The Fund also may manage portfolio duration by investing in interest rate futures contracts, options on interest rate futures contracts, structured notes and entering into swap agreements, provided that structured notes and swap agreements are determined by the Sub-Adviser to pose minimal counter-party credit risk. The 2024 (1958-1962) Fund is managed to continuously meet portfolio duration targets that correspond to projected payments, based on actuarially determined survivorship rates, of a single life annuity on the life of a person born in the year-range identified in the Fund's name. The portfolio duration targets are recalculated at least monthly based on a formula established by the Adviser (after consultation with Symetra Life Insurance Company ("Symetra Life")) at the Fund's inception. The formula will not change once the Fund commences operations. (The only variables in the formula are the amount of time remaining until each annual projected payment of the single life annuity and the prevailing interest rates on the recalculation date. The prevailing interest rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet the Fund's daily portfolio duration target by first, to the extent that such investments are available, investing in securities having cash flows similar to the projected payments of the single life annuity and then by balancing investments in securities with longer and shorter durations than the target duration. The portfolio duration target generally declines for the Fund over the life of the Fund, but will be substantially greater than zero at the Fund's termination date. As a result, to meet the portfolio duration target, the Fund will likely have an investment portfolio at its termination date of debt securities of substantial remaining duration. This in turn, will result in the market value of the Fund's investment portfolio at the termination date being significantly influenced by prevailing interest rates. Generally speaking, the higher the prevailing rates at the Fund's maturity, the less the Fund will receive from selling its assets and the lower the prevailing rates, the more the Fund will receive for selling its assets. Thus, the market value of such assets is inversely related to prevailing interest rates. The present value of a future series of payments decreases as the interest rate on which the present value is computed increases. Therefore, on the 2024 (1958-1962) Fund's termination date the present value of the annuity payments the investor is entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund will be less the higher the prevailing interest rates. The Fund's adherence to the portfolio duration target portfolio is intended to result in the Fund having on its termination date net assets approximately equal to the present value of the aggregate annuity payments investors are entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund. However, even if a Fund successfully adheres to the formula, there is no guarantee that it will achieve this intended result or its investment objective. Although the Fund has no current plans to close, there is no guarantee that the Fund will continue to accept new investments until the termination date. As of the date of this Prospectus, based on the current U.S. Treasury Zero Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2024 (1958-1962) Fund's portfolio duration target would have been 23.4 years.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the 2024 (1958-1962) Fund. The following additional risks could affect the value of your investment: · Credit Risk. The issuers of the bonds and other debt securities held by the       2024 (1958-1962) Fund may not be able to make interest or principal payments      when due. Even if these issuers are able to make interest or principal            payments, changes in an issuer's credit rating or the market's perception of   an issuer's creditworthiness may also affect the value of the Fund's investment   in that issuer by leading to greater volatility in the price of the security.         · Credit Default Swap Risk. In a credit default swap transaction, both the 2024   (1958-1962) Fund and its counter-party are exposed to the risk of default by      the other. In addition, the terms of most credit default swap transactions        require little or no initial investment by the seller in relation to the          notional amount of the swap and the corresponding risk. Therefore, small          changes in the market value of the reference security or group of securities      may produce disproportionate and substantial losses for the seller.             · Derivatives Risk. Derivatives are securities, such as futures contracts, whose   value is derived from that of other securities or indices. The 2024 (1958-1962)   Fund's investments in derivatives may pose risks in addition to those             associated with investing directly in securities or other investments.            Derivative securities are subject to a number of risks including liquidity,       interest rate, market, credit and management risks, the risk of improper          valuation, illiquidity of the derivatives, imperfect correlations with            underlying investments or the Fund's other portfolio holdings, lack of            availability and counterparty risk. Changes in the value of the derivative may   not correlate perfectly with the underlying asset, rate or index, and the Fund   could lose more than the principal amount invested. An investment in              derivatives may not perform as anticipated by the Sub-Adviser, may not be able   to be closed out at a favorable time or price. An investment in derivatives may   also increase the Fund's volatility and create investment leverage. When a        derivative is used as a substitute or alternative to a direct cash investment,   the transaction may not provide a return that corresponds precisely with that     of the cash investment; or, when used for hedging purposes, derivatives may not   provide the anticipated protection, causing the Fund to lose money on both the   derivatives transaction and the exposure the Fund sought to hedge.              · Extension Risk. When interest rates rise, certain obligations will be paid off   by the obligor more slowly than anticipated, causing the value of these           securities to fall.                                                             · Foreign Investing Risk. The securities of foreign issuers may be less liquid      and more volatile than securities of comparable U.S. issuers. Investments in      securities of foreign issuers, even those publicly traded in the United States,   may involve risks which are in addition to those inherent in domestic             investments. Foreign companies may not be subject to the same regulatory          requirements of U.S. companies, and as a consequence, there may be less           publicly available information about such companies. Also, foreign companies      may not be subject to uniform accounting, auditing, and financial reporting       standards and requirements comparable to those applicable to U.S. companies.      Foreign governments and foreign economies often are less stable than the U.S.     Government and the U.S. economy.                                                · Interest Rate Risk. In general, the value of bonds and other debt securities      falls when interest rates rise. Generally, the longer the duration of a debt      security, the greater is the negative effect on its value when rates              increase. Because zero coupon debt securities do not pay interest, the market     value of such securities can fall more dramatically than interest-paying          securities of similar maturities when interest rates rise. While bonds and        other debt securities normally fluctuate less in price than common stocks,        there have been extended periods of increases in interest rates that have         caused significant declines in bond prices.                                     · Management Risk. The 2024 (1958-1962) Fund is subject to management risk          because it is an actively managed portfolio. The portfolio manager's management   practices, investment strategies, and choice of investments might not work to     produce the desired results and the Fund might underperform other comparable      funds.                                                                          · Market Risk. The prices of the securities in which the 2024 (1958-1962) Fund      invests may decline for a number of reasons including in response to economic     developments and perceptions about the creditworthiness of individual             issuers. Longer-term bonds, in which the Fund will invest a majority of its       assets, are generally more volatile.                                            · New Fund Risk. The 2024 (1958-1962) Fund is new with no operating history and     there can be no assurance that the Fund will grow to or maintain an               economically viable size. If the Fund does not grow to or maintain an             economically viable size the Board may consider various alternatives, including   the liquidation of the Fund or the merger of the Fund into another mutual fund.    · Portfolio Duration Target Formula Risk. There is no guarantee that adherence to   the portfolio duration target formula will result in the Fund achieving its       investment objective.                                                           · Prepayment Risk. When interest rates fall, certain obligations will be paid off   by the obligor more quickly than originally anticipated, and the 2024             (1958-1962) Fund may have to invest the proceeds in securities with lower         yields (this is known as Reinvestment Risk).                                    · Termination Risk. Because the 2024 (1958-1962) Fund has a Termination Date and   it will invest a majority of its assets in securities that mature after the       Termination Date, the Fund may incur liquidation costs to liquidate its           portfolio.                                                                      · U.S. Government Issuer Risk. Treasury obligations may differ in their interest   rates, maturities, times of issuance and other characteristics. Obligations of   U.S. Government agencies and authorities are supported by varying degrees of      credit but generally are not backed by the full faith and credit of the U.S.      Government. No assurance can be given that the U.S. Government will provide       financial support to its agencies and authorities if it is not obligated by law   to do so.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the 2024 (1958-1962) Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the 2024 (1958-1962) Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the 2024 (1958-1962) Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-SYMETRA (1-800-796-3872)
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra Pension Reserve Fund 2024 (b. 1958-1962) (Prospectus Summary) | Symetra Pension Reserve Fund 2024 (b. 1958-1962) | Symetra Pension Reserve Fund 2024 (b. 1958-1962)
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.32%
Other Expenses	rr_OtherExpensesOverAssets	1.77%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.09%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.69%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.40%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	41
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	491

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2024 (b.1958-1962 (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra Pension Reserve Fund 2020 (b. 1953-1957) (Prospectus Summary) | Symetra Pension Reserve Fund 2020 (b. 1953-1957)
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra Pension Reserve Fund - 2020 (b.1953-1957)
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra Pension Reserve Fund - 2020 (1953-1957) (the "2020 (1953-1957) Fund" or the "Fund") seeks investment returns that would provide an amount on the Fund's termination date approximately equal to the then present value of specified lifetime annuity payments to be made to investors born in the year range identified in the Fund's name. As a result of its investment objective, a Pension Reserve Fund may not be a wise investment choice for an investor who does not anticipate applying his or her accumulation to the purchase of a lifetime annuity on or shortly after the Fund's termination date.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the 2020 (1953-1957) Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The 2020 (1953-1957) Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" is an estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the 2020 (1953-1957) Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The 2020 (1953-1957) Fund invests primarily in government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the three highest categories by an NRSRO or unrated securities that the Sub-Adviser determines are of comparable quality. The Fund also may invest in other types of dollar-denominated investment grade debt securities, including money market instruments and securities of foreign issuers. Most of the securities held by the Fund are zero coupon debt securities. Under normal market conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the two highest categories by an NRSRO, and investing in other permitted investments when government securities and corporate securities in the two highest categories are not available in sufficient quantities at a reasonable price or are not available in optimal durations or maturities.  The Fund also may manage portfolio duration by investing in interest rate futures contracts, options on interest rate futures contracts, structured notes and entering into swap agreements, provided that structured notes and swap agreements are determined by the Sub-Adviser to pose minimal counter-party credit risk. The 2020 (1953-1957) Fund is managed to continuously meet portfolio duration targets that correspond to projected payments, based on actuarially determined survivorship rates, of a single life annuity on the life of a person born in the year-range identified in the Fund's name. The portfolio duration targets are recalculated at least monthly based on a formula established by the Adviser (after consultation with Symetra Life Insurance Company ("Symetra Life")) at the Fund's inception. The formula will not change once the Fund commences operations. (The only variables in the formula are the amount of time remaining until each annual projected payment of the single life annuity and the prevailing interest rates on the recalculation date. The prevailing interest rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet the Fund's daily portfolio duration target by first, to the extent that such investments are available, investing in securities having cash flows similar to the projected payments of the single life annuity and then by balancing investments in securities with longer and shorter durations than the target duration. The portfolio duration target generally declines for the Fund over the life of the Fund, but will be substantially greater than zero at the Fund's termination date. As a result, to meet the portfolio duration target, the Fund will likely have an investment portfolio at its termination date of debt securities of substantial remaining duration. This in turn, will result in the market value of the Fund's investment portfolio at the termination date being significantly influenced by prevailing interest rates. Generally speaking, the higher the prevailing rates at the Fund's maturity, the less the Fund will receive from selling its assets and the lower the prevailing rates, the more the Fund will receive for selling its assets. Thus, the market value of such assets is inversely related to prevailing interest rates. The present value of a future series of payments decreases as the interest rate on which the present value is computed increases. Therefore, on the 2020 (1953-1957) Fund's termination date the present value of the annuity payments the investor is entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund will be less the higher the prevailing interest rates. The Fund's adherence to the portfolio duration target formula is intended to result in the Fund having on its termination date net assets approximately equal to the present value of the aggregate annuity payments investors are entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund. However, even if a Fund successfully adheres to the formula, there is no guarantee that it will achieve this intended result or its investment objective. Although the Fund has no current plans to close, there is no guarantee that the Fund will continue to accept new investments until the termination date. As of the date of this Prospectus, based on the current U.S. Treasury Zero Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2020 (1953-1957) Fund's portfolio duration target would have been 19.5 years.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the 2020 (1953-1957) Fund. The following additional risks could affect the value of your investment: · Credit Risk. The issuers of the bonds and other debt securities held by the       2020 (1953-1957) Fund may not be able to make interest or principal payments      when due. Even if these issuers are able to make interest or principal            payments, changes in an issuer's credit rating or the market's perception of an   issuer's creditworthiness may also affect the value of the Fund's investment in   that issuer by leading to greater volatility in the price of the security.         · Credit Default Swap Risk. In a credit default swap transaction, both the 2020   (1953-1957) Fund and its counter-party are exposed to the risk of default by      the other. In addition, the terms of most credit default swap transactions        require little or no initial investment by the seller in relation to the          notional amount of the swap and the corresponding risk. Therefore, small          changes in the market value of the reference security or group of securities      may produce disproportionate and substantial losses for the seller.             · Derivatives Risk. Derivatives are securities, such as futures contracts, whose   value is derived from that of other securities or indices. The 2020 (1953-1957)   Fund's investments in derivatives may pose risks in addition to those             associated with investing directly in securities or other investments.            Derivative securities are subject to a number of risks including liquidity,       interest rate, market, credit and management risks, the risk of improper          valuation, illiquidity of the derivatives, imperfect correlations with            underlying investments or the Fund's other portfolio holdings, lack of            availability and counterparty risk. Changes in the value of the derivative may   not correlate perfectly with the underlying asset, rate or index, and the Fund   could lose more than the principal amount invested. An investment in              derivatives may not perform as anticipated by the Sub-Adviser, may not be able   to be closed out at a favorable time or price. An investment in derivatives may   also increase the Fund's volatility and create investment leverage. When a        derivative is used as a substitute or alternative to a direct cash investment,   the transaction may not provide a return that corresponds precisely with that     of the cash investment; or, when used for hedging purposes, derivatives may not   provide the anticipated protection, causing the Fund to lose money on both the   derivatives transaction and the exposure the Fund sought to hedge.              · Extension Risk. When interest rates rise, certain obligations will be paid off   by the obligor more slowly than anticipated, causing the value of these           securities to fall.                                                             · Foreign Investing Risk. The securities of foreign issuers may be less liquid      and more volatile than securities of comparable U.S. issuers. Investments in      securities of foreign issuers, even those publicly traded in the United States,   may involve risks which are in addition to those inherent in domestic             investments. Foreign companies may not be subject to the same regulatory          requirements of U.S. companies, and as a consequence, there may be less           publicly available information about such companies. Also, foreign companies      may not be subject to uniform accounting, auditing, and financial reporting       standards and requirements comparable to those applicable to U.S. companies.      Foreign governments and foreign economies often are less stable than the U.S.     Government and the U.S. economy.                                                · Interest Rate Risk. In general, the value of bonds and other debt securities      falls when interest rates rise. Generally, the longer the duration of a debt      security, the greater is the negative effect on its value when rates              increase. Because zero coupon debt securities do not pay interest, the market     value of such securities can fall more dramatically than interest-paying          securities of similar maturities when interest rates rise. While bonds and        other debt securities normally fluctuate less in price than common stocks,        there have been extended periods of increases in interest rates that have         caused significant declines in bond prices.                                     · Management Risk. The 2020 (1953-1957) Fund is subject to management risk          because it is an actively managed portfolio. The portfolio manager's management   practices, investment strategies, and choice of investments might not work to     produce the desired results and the Fund might underperform other comparable      funds.                                                                          · Market Risk. The prices of the securities in which the 2020 (1953-1957) Fund      invests may decline for a number of reasons including in response to economic     developments and perceptions about the creditworthiness of individual             issuers. Longer-term bonds, in which the Fund will invest a majority of its       assets, are generally more volatile.                                            · New Fund Risk. The 2020 (1953-1957) Fund is new with no operating history and     there can be no assurance that the Fund will grow to or maintain an               economically viable size. If the Fund does not grow to or maintain an             economically viable size the Board may consider various alternatives, including   the liquidation of the Fund or the merger of the Fund into another mutual fund.    · Portfolio Duration Target Formula Risk. There is no guarantee that adherence to   the portfolio duration target formula will result in the Fund achieving its       investment objective.                                                           · Prepayment Risk. When interest rates fall, certain obligations will be paid off   by the obligor more quickly than originally anticipated, and the 2020             (1953-1957) Fund may have to invest the proceeds in securities with lower         yields (this is known as Reinvestment Risk).                                    · Termination Risk. Because the 2020 (1953-1957) Fund has a Termination Date and   it will invest a majority of its assets in securities that mature after the       Termination Date, the Fund may incur liquidation costs to liquidate its           portfolio.                                                                      · U.S. Government Issuer Risk. Treasury obligations may differ in their interest   rates, maturities, times of issuance and other characteristics. Obligations of   U.S. Government agencies and authorities are supported by varying degrees of      credit but generally are not backed by the full faith and credit of the U.S.      Government. No assurance can be given that the U.S. Government will provide       financial support to its agencies and authorities if it is not obligated by law   to do so.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the 2020 (1953-1957) Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the 2020 (1953-1957) Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the 2020 (1953-1957) Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-SYMETRA (1-800-796-3872)
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra Pension Reserve Fund 2020 (b. 1953-1957) (Prospectus Summary) | Symetra Pension Reserve Fund 2020 (b. 1953-1957) | Symetra Pension Reserve Fund 2020 (b. 1953-1957)
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.32%
Other Expenses	rr_OtherExpensesOverAssets	1.77%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.09%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.69%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.40%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	41
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	491

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2020 (b.1953-1957) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra Pension Reserve Fund 2028 (b. 1958-1962) (Prospectus Summary) | Symetra Pension Reserve Fund 2028 (b. 1958-1962)
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra Pension Reserve Fund - 2028 (b.1958-1962)
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra Pension Reserve Fund - 2028 (b.1958-1962) (the "2028 (1958-1962) Fund" or the "Fund") seeks investment returns that would provide an amount on the Fund's termination date approximately equal to the then present value of specified lifetime annuity payments to be made to investors born in the year range identified in the Fund's name. As a result of its investment objective, a Pension Reserve Fund may not be a wise investment choice for an investor who does not anticipate applying his or her accumulation to the purchase of a lifetime annuity on or shortly after the Fund's termination date.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the 2028 (1958-1962) Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The 2028 (1958-1962) Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" is an estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the 2028 (1958-1962) Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The 2028 (1958-1962) Fund invests primarily in government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the three highest categories by an NRSRO or unrated securities that the Sub-Adviser determines are of comparable quality. The Fund also may invest in other types of dollar-denominated investment grade debt securities, including money market instruments and securities of foreign issuers. Most of the securities held by the Fund are zero coupon debt securities. Under normal market conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the two highest categories by an NRSRO, and investing in other permitted investments when government securities and corporate securities in the two highest categories are not available in sufficient quantities at a reasonable price or are not available in optimal durations or maturities.  The Fund also may manage portfolio duration by investing in interest rate futures contracts, options on interest rate futures contracts, structured notes and entering into swap agreements, provided that structured notes and swap agreements are determined by the Sub-Adviser to pose minimal counter-party credit risk. The 2028 (1958-1962) Fund is managed to continuously meet portfolio duration targets that correspond to projected payments, based on actuarially determined survivorship rates, of a single life annuity on the life of a person born in the year-range identified in the Fund's name. The portfolio duration targets are recalculated at least monthly based on a formula established by the Adviser (after consultation with Symetra Life Insurance Company ("Symetra Life")) at the Fund's inception. The formula will not change once the Fund commences operations. (The only variables in the formula are the amount of time remaining until each annual projected payment of the single life annuity and the prevailing interest rates on the recalculation date. The prevailing interest rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet the Fund's daily portfolio duration target by first, to the extent that such investments are available, investing in securities having cash flows similar to the projected payments of the single life annuity and then by balancing investments in securities with longer and shorter durations than the target duration. The portfolio duration target generally declines for the Fund over the life of the Fund, but will be substantially greater than zero at the Fund's termination date. As a result, to meet the portfolio duration target, the Fund will have an investment portfolio at its termination date of debt securities of substantial remaining duration. This in turn, will likely result in the market value of the Fund's investment portfolio at the termination date being significantly influenced by prevailing interest rates. Generally speaking, the higher the prevailing rates at the Fund's maturity, the less the Fund will receive from selling its assets and the lower the prevailing rates, the more the Fund will receive for selling its assets. Thus, the market value of such assets is inversely related to prevailing interest rates. The present value of a future series of payments decreases as the interest rate on which the present value is computed increases. Therefore, on the 2028 (1958-1962) Fund's termination date the present value of the annuity payments the investor is entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund will be less the higher the prevailing interest rates. The Fund's adherence to the portfolio duration target formula is intended to result in the Fund having on its termination date net assets approximately equal to the present value of the aggregate annuity payments investors are entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund. However, even if a Fund successfully adheres to the formula, there is no guarantee that it will achieve this intended result or its investment objective. Although the Fund has no current plans to close, there is no guarantee that the Fund will continue to accept new investments until the termination date. As of the date of this Prospectus, based on the current U.S. Treasury Zero Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2028 (1958-1962) Fund's portfolio duration target would have been 25.5 years.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the 2028 (1958-1962) Fund. The following additional risks could affect the value of your investment: · Credit Risk. The issuers of the bonds and other debt securities held by the       2028 (1958-1962) Fund may not be able to make interest or principal payments      when due. Even if these issuers are able to make interest or principal            payments, changes in an issuer's credit rating or the market's perception of an   issuer's creditworthiness may also affect the value of the Fund's investment in   that issuer by leading to greater volatility in the price of the security.      · Credit Default Swap Risk. In a credit default swap transaction, both the 2028   (1958-1962) Fund and its counter-party are exposed to the risk of default by      the other. In addition, the terms of most credit default swap transactions        require little or no initial investment by the seller in relation to the          notional amount of the swap and the corresponding risk. Therefore, small          changes in the market value of the reference security or group of securities      may produce disproportionate and substantial losses for the seller.                · Derivatives Risk. Derivatives are securities, such as futures contracts, whose   value is derived from that of other securities or indices. The 2028 (1958-1962)   Fund's investments in derivatives may pose risks in addition to those             associated with investing directly in securities or other investments.            Derivative securities are subject to a number of risks including liquidity,       interest rate, market, credit and management risks, the risk of improper          valuation, illiquidity of the derivatives, imperfect correlations with            underlying investments or the Fund's other portfolio holdings, lack of            availability and counterparty risk. Changes in the value of the derivative may   not correlate perfectly with the underlying asset, rate or index, and the Fund   could lose more than the principal amount invested. An investment in              derivatives may not perform as anticipated by the Sub-Adviser, may not be able   to be closed out at a favorable time or price. An investment in derivatives may   also increase the Fund's volatility and create investment leverage. When a        derivative is used as a substitute or alternative to a direct cash investment,   the transaction may not provide a return that corresponds precisely with that     of the cash investment; or, when used for hedging purposes, derivatives may not   provide the anticipated protection, causing the Fund to lose money on both the   derivatives transaction and the exposure the Fund sought to hedge.                 · Extension Risk. When interest rates rise, certain obligations will be paid off   by the obligor more slowly than anticipated, causing the value of these           securities to fall.                                                                · Foreign Investing Risk. The securities of foreign issuers may be less liquid      and more volatile than securities of comparable U.S. issuers. Investments in      securities of foreign issuers, even those publicly traded in the United States,   may involve risks which are in addition to those inherent in domestic             investments. Foreign companies may not be subject to the same regulatory          requirements of U.S. companies, and as a consequence, there may be less           publicly available information about such companies. Also, foreign companies      may not be subject to uniform accounting, auditing, and financial reporting       standards and requirements comparable to those applicable to U.S. companies.      Foreign governments and foreign economies often are less stable than the U.S.     Government and the U.S. economy.                                                   · Interest Rate Risk. In general, the value of bonds and other debt securities      falls when interest rates rise. Generally, the longer the duration of a debt      security, the greater is the negative effect on its value when rates              increase. Because zero coupon debt securities do not pay interest, the market     value of such securities can fall more dramatically than interest-paying          securities of similar maturities when interest rates rise. While bonds and        other debt securities normally fluctuate less in price than common stocks,        there have been extended periods of increases in interest rates that have         caused significant declines in bond prices.                                        · Management Risk. The 2028 (1958-1962) Fund is subject to management risk          because it is an actively managed portfolio. The portfolio manager's management   practices, investment strategies, and choice of investments might not work to     produce the desired results and the Fund might underperform other comparable      funds.                                                                             · Market Risk. The prices of the securities in which the 2028 (1958-1962) Fund      invests may decline for a number of reasons including in response to economic     developments and perceptions about the creditworthiness of individual             issuers. Longer-term bonds, in which the Fund will invest a majority of its       assets, are generally more volatile.                                               · New Fund Risk. The 2028 (1958-1962) Fund is new with no operating history and     there can be no assurance that the Fund will grow to or maintain an               economically viable size. If the Fund does not grow to or maintain an             economically viable size the Board may consider various alternatives, including   the liquidation of the Fund or the merger of the Fund into another mutual fund. · Portfolio Duration Target Formula Risk. There is no guarantee that adherence to   the portfolio duration target formula will result in the Fund achieving its       investment objective.                                                              · Prepayment Risk. When interest rates fall, certain obligations will be paid off   by the obligor more quickly than originally anticipated, and the 2028             (1958-1962) Fund may have to invest the proceeds in securities with lower         yields (this is known as Reinvestment Risk).                                    · Termination Risk. Because the 2028 (1958-1962) Fund has a Termination Date and   it will invest a majority of its assets in securities that mature after the       Termination Date, the Fund may incur liquidation costs to liquidate its           portfolio.                                                                      · U.S. Government Issuer Risk. Treasury obligations may differ in their interest   rates, maturities, times of issuance and other characteristics. Obligations of   U.S. Government agencies and authorities are supported by varying degrees of      credit but generally are not backed by the full faith and credit of the U.S.      Government. No assurance can be given that the U.S. Government will provide       financial support to its agencies and authorities if it is not obligated by law   to do so.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the 2028 (1958-1962) Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the 2028 (1958-1962) Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the 2028 (1958-1962) Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-796-3872
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra Pension Reserve Fund 2028 (b. 1958-1962) (Prospectus Summary) | Symetra Pension Reserve Fund 2028 (b. 1958-1962) | Symetra Pension Reserve Fund 2028 (b. 1958-1962)
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.32%
Other Expenses	rr_OtherExpensesOverAssets	1.77%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.09%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.69%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.40%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	41
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	491

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2028 (b.1958-1962) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra Pension Reserve Fund 2016 (b. 1942-1947) (Prospectus Summary) | Symetra Pension Reserve Fund 2016 (b. 1942-1947)
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra Pension Reserve Fund - 2016 (b.1942-1947)
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra Pension Reserve Fund - 2016 (b.1942-1947) (the "2016 (1942-1947) Fund" or the "Fund") seeks investment returns that would provide an amount on the Fund's termination date approximately equal to the then present value of specified lifetime annuity payments to be made to investors born in the year range identified in the Fund's name. As a result of its investment objective, a Pension Reserve Fund may not be a wise investment choice for an investor who does not anticipate applying his or her accumulation to the purchase of a lifetime annuity on or shortly after the Fund's termination date.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the 2016 (1942-1947) Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The 2016 (1942-1947) Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" is an estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the 2016 (1942-1947) Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The 2016 (1942-1947) Fund invests primarily in government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the three highest categories by an NRSRO or unrated securities that the Sub-Adviser determines are of comparable quality. The Fund also may invest in other types of dollar-denominated investment grade debt securities, including money market instruments and securities of foreign issuers. Most of the securities held by the Fund are zero coupon debt securities. Under normal market conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the two highest categories by an NRSRO, and investing in other permitted investments when government securities and corporate securities in the two highest categories are not available in sufficient quantities at a reasonable price or are not available in optimal durations or maturities.  The Fund also may manage portfolio duration by investing in interest rate futures contracts, options on interest rate futures contracts, structured notes and entering into swap agreements, provided that structured notes and swap agreements are determined by the Sub-Adviser to pose minimal counter-party credit risk. The 2016 (1942-1947) Fund is managed to continuously meet portfolio duration targets that correspond to projected payments, based on actuarially determined survivorship rates, of a single life annuity on the life of a person born in the year-range identified in the Fund's name. The portfolio duration targets are recalculated at least monthly based on a formula established by the Adviser (after consultation with Symetra Life Insurance Company ("Symetra Life")) at the Fund's inception. The formula will not change once the Fund commences operations. (The only variables in the formula are the amount of time remaining until each annual projected payment of the single life annuity and the prevailing interest rates on the recalculation date. The prevailing interest rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet the Fund's daily portfolio duration target by first, to the extent that such investments are available, investing in securities having cash flows similar to the projected payments of the single life annuity and then by balancing investments in securities with longer and shorter durations than the target duration. The portfolio duration target generally declines for the Fund over the life of the Fund, but will be substantially greater than zero at the Fund's termination date. As a result, to meet the portfolio duration target, the Fund will likely have an investment portfolio at its termination date of debt securities of substantial remaining duration. This in turn, will result in the market value of the Fund's investment portfolio at the termination date being significantly influenced by prevailing interest rates. Generally speaking, the higher the prevailing rates at the Fund's maturity, the less the Fund will receive from selling its assets and the lower the prevailing rates, the more the Fund will receive for selling its assets. Thus, the market value of such assets is inversely related to prevailing interest rates. The present value of a future series of payments decreases as the interest rate on which the present value is computed increases. Therefore, on the 2016 (1942-1947) Fund's termination date the present value of the annuity payments the investor is entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund will be less the higher the prevailing interest rates. The Fund's adherence to the portfolio duration target formula is intended to result in the Fund having on its termination date net assets approximately equal to the present value of the aggregate annuity payments investors are entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund. However, even if a Fund successfully adheres to the formula, there is no guarantee that it will achieve this intended result or its investment objective. Although the Fund has no current plans to close, there is no guarantee that the Fund will continue to accept new investments until the termination date. As of the date of this Prospectus, based on the current U.S. Treasury Zero Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2016 (1942-1947) Fund's portfolio duration target would have been 13.8 years.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the 2016 (1942-1947) Fund. The following additional risks could affect the value of your investment: · Credit Risk. The issuers of the bonds and other debt securities held by the     2016 (1942-1947) Fund may not be able to make interest or principal payments   when due. Even if these issuers are able to make interest or principal          payments, changes in an issuer's credit rating or the market's perception of   an issuer's creditworthiness may also affect the value of the Fund's            investment in that issuer by leading to greater volatility in the price of      the security.                                                                 · Credit Default Swap Risk. In a credit default swap transaction, both the 2016   (1942-1947) Fund and its counter-party are exposed to the risk of default by      the other. In addition, the terms of most credit default swap transactions        require little or no initial investment by the seller in relation to the          notional amount of the swap and the corresponding risk. Therefore, small          changes in the market value of the reference security or group of securities      may produce disproportionate and substantial losses for the seller.                · Derivatives Risk. Derivatives are securities, such as futures contracts, whose   value is derived from that of other securities or indices. The 2016 (1942-1947)   Fund's investments in derivatives may pose risks in addition to those             associated with investing directly in securities or other investments.            Derivative securities are subject to a number of risks including liquidity,       interest rate, market, credit and management risks, the risk of improper          valuation, illiquidity of the derivatives, imperfect correlations with            underlying investments or the Fund's other portfolio holdings, lack of            availability and counterparty risk. Changes in the value of the derivative may   not correlate perfectly with the underlying asset, rate or index, and the Fund   could lose more than the principal amount invested. An investment in              derivatives may not perform as anticipated by the Sub-Adviser, may not be able   to be closed out at a favorable time or price. An investment in derivatives may   also increase the Fund's volatility and create investment leverage. When a        derivative is used as a substitute or alternative to a direct cash investment,   the transaction may not provide a return that corresponds precisely with that     of the cash investment; or, when used for hedging purposes, derivatives may not   provide the anticipated protection, causing the Fund to lose money on both the   derivatives transaction and the exposure the Fund sought to hedge.                 · Extension Risk. When interest rates rise, certain obligations will be paid off   by the obligor more slowly than anticipated, causing the value of these           securities to fall.                                                                · Foreign Investing Risk. The securities of foreign issuers may be less liquid      and more volatile than securities of comparable U.S. issuers. Investments in      securities of foreign issuers, even those publicly traded in the United States,   may involve risks which are in addition to those inherent in domestic             investments. Foreign companies may not be subject to the same regulatory          requirements of U.S. companies, and as a consequence, there may be less           publicly available information about such companies. Also, foreign companies      may not be subject to uniform accounting, auditing, and financial reporting       standards and requirements comparable to those applicable to U.S. companies.      Foreign governments and foreign economies often are less stable than the U.S.     Government and the U.S. economy.                                                · Interest Rate Risk. In general, the value of bonds and other debt securities      falls when interest rates rise. Generally, the longer the duration of a debt      security, the greater is the negative effect on its value when rates increase.   Because zero coupon debt securities do not pay interest, the market value of      such securities can fall more dramatically than interest-paying securities of     similar maturities when interest rates rise. While bonds and other debt           securities normally fluctuate less in price than common stocks, there have been   extended periods of increases in interest rates that have caused significant      declines in bond prices.                                                        · Management Risk. The Fund is subject to management risk because it is an          actively managed portfolio. The portfolio manager's management practices,         investment strategies, and choice of investments might not work to produce the   desired results and the Fund might underperform other comparable funds.            · Market Risk. The prices of the securities in which the 2016 (1942-1947) Fund      invests may decline for a number of reasons including in response to economic     developments and perceptions about the creditworthiness of individual             issuers. Longer-term bonds, in which the Fund will invest a majority of its       assets, are generally more volatile.                                               · New Fund Risk. The 2016 (1942-1947) Fund is new with no operating history and     there can be no assurance that the Fund will grow to or maintain an               economically viable size. If the Fund does not grow to or maintain an             economically viable size the Board may consider various alternatives, including   the liquidation of the Fund or the merger of the Fund into another mutual fund. · Portfolio Duration Target Formula Risk. There is no guarantee that adherence to   the portfolio duration target formula will result in the Fund achieving its       investment objective.                                                              · Prepayment Risk. When interest rates fall, certain obligations will be paid off   by the obligor more quickly than originally anticipated, and the 2016             (1942-1947) Fund may have to invest the proceeds in securities with lower         yields (this is known as Reinvestment Risk).                                       · Termination Risk. Because the 2016 (1942-1947) Fund has a Termination Date and   it will invest a majority of its assets in securities that mature after the       Termination Date, the Fund may incur liquidation costs to liquidate its           portfolio.                                                                         · U.S. Government Issuer Risk. Treasury obligations may differ in their interest   rates, maturities, times of issuance and other characteristics. Obligations of   U.S. Government agencies and authorities are supported by varying degrees of      credit but generally are not backed by the full faith and credit of the U.S.      Government. No assurance can be given that the U.S. Government will provide       financial support to its agencies and authorities if it is not obligated by law   to do so.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the 2016 (1942-1947) Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the 2016 (1942-1947) Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the 2016 (1942-1947) Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-SYMETRA (1-800-796-3872)
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra Pension Reserve Fund 2016 (b. 1942-1947) (Prospectus Summary) | Symetra Pension Reserve Fund 2016 (b. 1942-1947) | Symetra Pension Reserve Fund 2016 (b. 1942-1947)
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.32%
Other Expenses	rr_OtherExpensesOverAssets	1.77%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.09%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.69%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.40%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	41
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	491

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2016 (b.1942-1947) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Symetra Pension Reserve Fund 2016 (b. 1953-1957) (Prospectus Summary) | Symetra Pension Reserve Fund 2016 (b. 1953-1957)

Symetra Pension Reserve Fund - 2016 (b.1953-1957)

Investment Objective

The Symetra Pension Reserve Fund - 2016 (b.1953-1957) (the "2016 (1953-1957)
Fund" or the "Fund") seeks investment returns that would provide an amount on
the Fund's termination date approximately equal to the then present value of
specified lifetime annuity payments to be made to investors born in the year
range identified in the Fund's name. As a result of its investment objective,
a Pension Reserve Fund may not be a wise investment choice for an investor
who does not anticipate applying his or her accumulation to the purchase of a
lifetime annuity on or shortly after the Fund's termination date.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the 2016 (1953-1957) Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity or variable life insurance contract level. If
those additional fees and expenses were included, overall expenses would be
higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra Pension Reserve Fund 2016 (b. 1953-1957)
Management Fees		0.32%
Other Expenses	[1]	1.77%
Total Annual Fund Operating Expenses		2.09%
Less: Fee Waiver and/or Expense Reimbursement	[2]	(1.69%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.40%

Example

This Example is intended to help you compare the cost of investing in the 2016
(1953-1957) Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated and
then redeem all of your shares at the end of those periods. The Example also
assumes that your investment has a 5% return each year and that the Fund's
operating expenses remain the same (taking into account the Expense Cap and Fee
Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra Pension Reserve Fund 2016 (b. 1953-1957)	41	491

Portfolio Turnover

The 2016 (1953-1957) Fund pays transaction costs, such as commissions, when it
buys and sells securities (or "turns over" its portfolio). A higher portfolio
turnover rate may indicate higher transaction costs and may result in higher
taxes when Fund shares are held in a taxable account. These costs, which are not
reflected in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Fund

The 2016 (1953-1957) Fund invests primarily in government securities and
dollar-denominated corporate debt securities rated, at the time of purchase,
in the three highest categories by an NRSRO or unrated securities that the
Sub-Adviser determines are of comparable quality. The Fund also may invest in
other types of dollar-denominated investment grade debt securities, including
money market instruments and securities of foreign issuers. Most of the
securities held by the Fund are zero coupon debt securities. Under normal market
conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring
government securities and dollar-denominated corporate debt securities rated, at
the time of purchase, in the two highest categories by an NRSRO, and investing
in other permitted investments when government securities and corporate
securities in the two highest categories are not available in sufficient
quantities at a reasonable price or are not available in optimal durations or
maturities.  The Fund also may manage portfolio duration by investing in
interest rate futures contracts, options on interest rate futures contracts,
structured notes and entering into swap agreements, provided that structured
notes and swap agreements are determined by the Sub-Adviser to pose minimal
counter-party credit risk.

The 2016 (1953-1957) Fund is managed to continuously meet portfolio duration
targets that correspond to projected payments, based on actuarially determined
survivorship rates, of a single life annuity on the life of a person born in the
year-range identified in the Fund's name. The portfolio duration targets are
recalculated at least monthly based on a formula established by the Adviser
(after consultation with Symetra Life Insurance Company ("Symetra Life")) at the
Fund's inception. The formula will not change once the Fund commences operations.
(The only variables in the formula are the amount of time remaining until each
annual projected payment of the single life annuity and the prevailing interest
rates on the recalculation date. The prevailing interest rates are derived from
the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under
normal market conditions, the Sub-Adviser seeks to meet the Fund's daily
portfolio duration target by first, to the extent that such investments are
available, investing in securities having cash flows similar to the projected
payments of the single life annuity and then by balancing investments in
securities with longer and shorter durations than the target duration. The
portfolio duration target generally declines for the Fund over the life of the
Fund, but will be substantially greater than zero at the Fund's termination
date. As a result, to meet the portfolio duration target, the Fund will likely
have an investment portfolio at its termination date of debt securities of
substantial remaining duration. This in turn, will result in the market value
of the Fund's investment portfolio at the termination date being significantly
influenced by prevailing interest rates. Generally speaking, the higher the
prevailing rates at the Fund's maturity, the less the Fund will receive from
selling its assets and the lower the prevailing rates, the more the Fund will
receive for selling its assets. Thus, the market value of such assets is
inversely related to prevailing interest rates.

The present value of a future series of payments decreases as the interest rate
on which the present value is computed increases. Therefore, on the 2016
(1953-1957) Fund's termination date the present value of the annuity payments
the investor is entitled to receive as a result of owning accumulation units in
the sub-account of the Symetra Resource Variable Account B that invests in
shares of the Fund will be less the higher the prevailing interest rates. The
Fund's adherence to the portfolio duration target formula is intended to result
in the Fund having on its termination date net assets approximately equal to the
present value of the aggregate annuity payments investors are entitled to
receive as a result of owning accumulation units in the sub-account of the Symetra
Resource Variable Account B that invests in shares of the Fund. However, even
if a Fund successfully adheres to the formula, there is no guarantee that it
will achieve this intended result or its investment objective. Although the
Fund has no current plans to close, there is no guarantee that the Fund will
continue to accept new investments until the termination date.

As of the date of this Prospectus, based on the current U.S. Treasury Zero
Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2016
(1953-1957) Fund's portfolio duration target would have been 17.2 years.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the 2016
(1953-1957) Fund. The following additional risks could affect the value of your
investment:

· Credit Risk. The issuers of the bonds and other debt securities held by the    
  2016 (1953-1957) Fund may not be able to make interest or principal payments   
  when due. Even if these issuers are able to make interest or principal         
  payments, changes in an issuer's credit rating or the market's perception of an
  issuer's creditworthiness may also affect the value of the Fund's investment in
  that issuer by leading to greater volatility in the price of the security.     
  
· Credit Default Swap Risk. In a credit default swap transaction, both the 2016
  (1953-1957) Fund and its counter-party are exposed to the risk of default by   
  the other. In addition, the terms of most credit default swap transactions     
  require little or no initial investment by the seller in relation to the       
  notional amount of the swap and the corresponding risk. Therefore, small       
  changes in the market value of the reference security or group of securities   
  may produce disproportionate and substantial losses for the seller.            

· Derivatives Risk. Derivatives are securities, such as futures contracts, whose
  value is derived from that of other securities or indices. The 2016 (1953-1957)
  Fund's investments in derivatives may pose risks in addition to those          
  associated with investing directly in securities or other investments.         
  Derivative securities are subject to a number of risks including liquidity,    
  interest rate, market, credit and management risks, the risk of improper       
  valuation, illiquidity of the derivatives, imperfect correlations with         
  underlying investments or the Fund's other portfolio holdings, lack of         
  availability and counterparty risk. Changes in the value of the derivative may
  not correlate perfectly with the underlying asset, rate or index, and the Fund
  could lose more than the principal amount invested. An investment in           
  derivatives may not perform as anticipated by the Sub-Adviser, may not be able
  to be closed out at a favorable time or price. An investment in derivatives may
  also increase the Fund's volatility and create investment leverage. When a     
  derivative is used as a substitute or alternative to a direct cash investment,
  the transaction may not provide a return that corresponds precisely with that  
  of the cash investment; or, when used for hedging purposes, derivatives may not
  provide the anticipated protection, causing the Fund to lose money on both the
  derivatives transaction and the exposure the Fund sought to hedge.             

· Extension Risk. When interest rates rise, certain obligations will be paid off
  by the obligor more slowly than anticipated, causing the value of these        
  securities to fall.                                                            

· Foreign Investing Risk. The securities of foreign issuers may be less liquid   
  and more volatile than securities of comparable U.S. issuers. Investments in   
  securities of foreign issuers, even those publicly traded in the United States,
  may involve risks which are in addition to those inherent in domestic          
  investments. Foreign companies may not be subject to the same regulatory       
  requirements of U.S. companies, and as a consequence, there may be less        
  publicly available information about such companies. Also, foreign companies   
  may not be subject to uniform accounting, auditing, and financial reporting    
  standards and requirements comparable to those applicable to U.S. companies.   
  Foreign governments and foreign economies often are less stable than the U.S.  
  Government and the U.S. economy.                                               

· Interest Rate Risk. In general, the value of bonds and other debt securities   
  falls when interest rates rise. Generally, the longer the duration of a debt   
  security, the greater is the negative effect on its value when rates           
  increase. Because zero coupon debt securities do not pay interest, the market  
  value of such securities can fall more dramatically than interest-paying       
  securities of similar maturities when interest rates rise. While bonds and     
  other debt securities normally fluctuate less in price than common stocks,     
  there have been extended periods of increases in interest rates that have      
  caused significant declines in bond prices.                                    

· Management Risk. The 2016 (1953-1957) Fund is subject to management risk       
  because it is an actively managed portfolio. The portfolio manager's management
  practices, investment strategies, and choice of investments might not work to  
  produce the desired results and the Fund might underperform other comparable   
  funds.                                                                         

· Market Risk. The prices of the securities in which the 2016 (1953-1957) Fund   
  invests may decline for a number of reasons including in response to economic  
  developments and perceptions about the creditworthiness of individual          
  issuers. Longer-term bonds, in which the Fund will invest a majority of its    
  assets, are generally more volatile.                                           

· New Fund Risk. The 2016 (1953-1957) Fund is new with no operating history and  
  there can be no assurance that the Fund will grow to or maintain an            
  economically viable size. If the Fund does not grow to or maintain an          
  economically viable size the Board may consider various alternatives, including
  the liquidation of the Fund or the merger of the Fund into another mutual fund.
  
· Portfolio Duration Target Formula Risk. There is no guarantee that adherence to
  the portfolio duration target formula will result in the Fund achieving its    
  investment objective.                                                          

· Prepayment Risk. When interest rates fall, certain obligations will be paid off
  by the obligor more quickly than originally anticipated, and the 2016          
  (1953-1957) Fund may have to invest the proceeds in securities with lower      
  yields (this is known as Reinvestment Risk).                                   

· Termination Risk. Because the 2016 (1953-1957) Fund has a Termination Date and
  it will invest a majority of its assets in securities that mature after the    
  Termination Date, the Fund may incur liquidation costs to liquidate its        
  portfolio.                                                                     

· U.S. Government Issuer Risk. Treasury obligations may differ in their interest
  rates, maturities, times of issuance and other characteristics. Obligations of
  U.S. Government agencies and authorities are supported by varying degrees of   
  credit but generally are not backed by the full faith and credit of the U.S.   
  Government. No assurance can be given that the U.S. Government will provide    
  financial support to its agencies and authorities if it is not obligated by law
  to do so.

Performance

When the 2016 (1953-1957) Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2016 (b.1953-1957) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Symetra Pension Reserve Fund 2024 (b. 1948-1952) (Prospectus Summary) | Symetra Pension Reserve Fund 2024 (b. 1948-1952)

Symetra Pension Reserve Fund - 2024 (b.1948-1952)

Investment Objective

The Symetra Pension Reserve Fund - 2024 (b.1948-1952) (the "2024 (1948-1952)
Fund" or the "Fund") seeks investment returns that would provide an amount on
the Fund's termination date approximately equal to the then present value of
specified lifetime annuity payments to be made to investors born in the year
range identified in the Fund's name. As a result of its investment objective,
a Pension Reserve Fund may not be a wise investment choice for an investor who
does not anticipate applying his or her accumulation to the purchase of a
lifetime annuity on or shortly after the Fund's termination date.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the 2024 (1948-1952) Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity or variable life insurance contract level. If
those additional fees and expenses were included, overall expenses would be
higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra Pension Reserve Fund 2024 (b. 1948-1952)
Management Fees		0.32%
Other Expenses	[1]	1.77%
Total Annual Fund Operating Expenses		2.09%
Less: Fee Waiver and Expense Reimbursement	[2]	(1.69%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.40%

Example

This Example is intended to help you compare the cost of investing in the 2024
(1948-1952) Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated and
then redeem all of your shares at the end of those periods. The Example also
assumes that your investment has a 5% return each year and that the Fund's
operating expenses remain the same (taking into account the Expense Cap and Fee
Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra Pension Reserve Fund 2024 (b. 1948-1952)	41	491

Portfolio Turnover

The 2024 (1948-1952) Fund pays transaction costs, such as commissions, when it
buys and sells securities (or "turns over" its portfolio). A higher portfolio
turnover rate may indicate higher transaction costs and may result in higher
taxes when Fund shares are held in a taxable account. These costs, which are not
reflected in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Fund

The 2024 (1948-1952) Fund invests primarily in government securities and
dollar-denominated corporate debt securities rated, at the time of purchase,
in the three highest categories by an NRSRO or unrated securities that the
Sub-Adviser determines are of comparable quality. The Fund also may invest in
other types of dollar-denominated investment grade debt securities, including
money market instruments and securities of foreign issuers. Most of the
securities held by the Fund are zero coupon debt securities. Under normal market
conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring
government securities and dollar-denominated corporate debt securities rated, at
the time of purchase, in the two highest categories by an NRSRO, and investing
in other permitted investments when government securities and corporate
securities in the two highest categories are not available in sufficient
quantities at a reasonable price or are not available in optimal durations or
maturities.  The Fund also may manage portfolio duration by investing in
interest rate futures contracts, options on interest rate futures contracts,
structured notes and entering into swap agreements, provided that structured
notes and swap agreements are determined by the Sub-Adviser to pose minimal
counter-party credit risk.

The 2024 (1948-1952) Fund is managed to continuously meet portfolio duration
targets that correspond to projected payments, based on actuarially determined
survivorship rates, of a single life annuity on the life of a person born in the
year-range identified in the Fund's name. The portfolio duration targets are
recalculated at least monthly based on a formula established by the Adviser
(after consultation with Symetra Life Insurance Company ("Symetra Life")) at the
Fund's inception. The formula will not change once the Fund commences
operations. (The only variables in the formula are the amount of time remaining
until each annual projected payment of the single life annuity and the
prevailing interest rates on the recalculation date. The prevailing interest
rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by
interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet
the Fund's daily portfolio duration target by first, to the extent that such
investments are available, investing in securities having cash flows similar to
the projected payments of the single life annuity and then by balancing
investments in securities with longer and shorter durations than the target
duration. The portfolio duration target generally declines for the Fund over the
life of the Fund, but will be substantially greater than zero at the Fund's
termination date. As a result, to meet the portfolio duration target, the Fund
will likely have an investment portfolio at its termination date of debt
securities of substantial remaining duration. This in turn, will result in the
market value of the Fund's investment portfolio at the termination date being
significantly influenced by prevailing interest rates. Generally speaking, the
higher the prevailing rates at the Fund's maturity, the less the Fund will
receive from selling its assets and the lower the prevailing rates, the more the
Fund will receive for selling its assets. Thus, the market value of such assets
is inversely related to prevailing interest rates.

The present value of a future series of payments decreases as the interest rate
on which the present value is computed increases. Therefore, on the 2024
(1948-1952) Fund's termination date the present value of the annuity payments
the investor is entitled to receive as a result of owning accumulation units in
the sub-account of the Symetra Resource Variable Account B that invests in
shares of the Fund will be less the higher the prevailing interest rates. The
Fund's adherence to the portfolio duration target formula is intended to result
in the Fund having on its termination date net assets approximately equal to the
present value of the aggregate annuity payments investors are entitled to
receive as a result of owning accumulation units in the sub-account of the
Symetra Resource Variable Account B that invests in shares of the Fund. However,
even if a Fund successfully adheres to the formula, there is no guarantee that
it will achieve this intended result or its investment objective. Although the
Fund has no current plans to close, there is no guarantee that the Fund will
continue to accept new investments until the termination date.

As of the date of this Prospectus, based on the current U.S. Treasury Zero
Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2024
(1948-1952) Fund's portfolio duration target would have been 20.1 years.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the 2024
(1948-1952) Fund. The following additional risks could affect the value of your
investment:

· Credit Risk. The issuers of the bonds and other debt securities held by the    
  2024 (1948-1952) Fund may not be able to make interest or principal payments   
  when due. Even if these issuers are able to make interest or principal         
  payments, changes in an issuer's credit rating or the market's perception of an
  issuer's creditworthiness may also affect the value of the Fund's investment in
  that issuer by leading to greater volatility in the price of the security.     

· Credit Default Swap Risk. In a credit default swap transaction, both the 2024
  (1948-1952) Fund and its counter-party are exposed to the risk of default by   
  the other. In addition, the terms of most credit default swap transactions     
  require little or no initial investment by the seller in relation to the       
  notional amount of the swap and the corresponding risk. Therefore, small       
  changes in the market value of the reference security or group of securities   
  may produce disproportionate and substantial losses for the seller.            

· Derivatives Risk. Derivatives are securities, such as futures contracts, whose
  value is derived from that of other securities or indices. The Fund's          
  investments in derivatives may pose risks in addition to those associated with
  investing directly in securities or other investments. Derivative securities   
  are subject to a number of risks including liquidity, interest rate, market,   
  credit and management risks, the risk of improper valuation, illiquidity of the
  derivatives, imperfect correlations with underlying investments or the Fund's  
  other portfolio holdings, lack of availability and counterparty risk. Changes  
  in the value of the derivative may not correlate perfectly with the underlying
  asset, rate or index, and the Fund could lose more than the principal amount   
  invested. An investment in derivatives may not perform as anticipated by the   
  Sub-Adviser, may not be able to be closed out at a favorable time or price. An
  investment in derivatives may also increase the Fund's volatility and create   
  investment leverage. When a derivative is used as a substitute or alternative  
  to a direct cash investment, the transaction may not provide a return that     
  corresponds precisely with that of the cash investment; or, when used for      
  hedging purposes, derivatives may not provide the anticipated protection,      
  causing the Fund to lose money on both the derivatives transaction and the     
  exposure the Fund sought to hedge.                                             
  
· Extension Risk. When interest rates rise, certain obligations will be paid off
  by the obligor more slowly than anticipated, causing the value of these        
  securities to fall.                                                            
  
· Foreign Investing Risk. The securities of foreign issuers may be less liquid   
  and more volatile than securities of comparable U.S. issuers. Investments in   
  securities of foreign issuers, even those publicly traded in the United States,
  may involve risks which are in addition to those inherent in domestic          
  investments. Foreign companies may not be subject to the same regulatory       
  requirements of U.S. companies, and as a consequence, there may be less        
  publicly available information about such companies. Also, foreign companies   
  may not be subject to uniform accounting, auditing, and financial reporting    
  standards and requirements comparable to those applicable to U.S. companies.   
  Foreign governments and foreign economies often are less stable than the U.S.  
  Government and the U.S. economy.                                               
  
· Interest Rate Risk. In general, the value of bonds and other debt securities   
  falls when interest rates rise. Generally, the longer the duration of a debt   
  security, the greater is the negative effect on its value when rates           
  increase. Because zero coupon debt securities do not pay interest, the market  
  value of such securities can fall more dramatically than interest-paying       
  securities of similar maturities when interest rates rise. While bonds and     
  other debt securities normally fluctuate less in price than common stocks,     
  there have been extended periods of increases in interest rates that have      
  caused significant declines in bond prices.                                    

· Management Risk. The 2024 (1948-1952) Fund is subject to management risk       
  because it is an actively managed portfolio. The portfolio manager's management
  practices, investment strategies, and choice of investments might not work to  
  produce the desired results and the Fund might underperform other comparable   
  funds.                                                                         

· Market Risk. The prices of the securities in which the 2024 (1948-1952) Fund   
  invests may decline for a number of reasons including in response to economic  
  developments and perceptions about the creditworthiness of individual          
  issuers. Longer-term bonds, in which the Fund will invest a majority of its    
  assets, are generally more volatile.                                           

· New Fund Risk. The 2024 (1948-1952) Fund is new with no operating history and  
  there can be no assurance that the Fund will grow to or maintain an            
  economically viable size. If the Fund does not grow to maintain an economically
  viable size the Board may consider various alternatives, including the         
  liquidation of the Fund or the merger of the Fund into another mutual fund.    

· Portfolio Duration Target Formula Risk. There is no guarantee that adherence to
  the portfolio duration target formula will result in the Fund achieving its    
  investment objective.                                                          
  
· Prepayment Risk. When interest rates fall, certain obligations will be paid off
  by the obligor more quickly than originally anticipated, and the Fund may have
  to invest the proceeds in securities with lower yields (this is known as       
  Reinvestment Risk).                                                            
  
· Termination Risk. Because the 2024 (1948-1952) Fund has a Termination Date and
  it will invest a majority of its assets in securities that mature after the    
  Termination Date, the Fund may incur liquidation costs to liquidate its        
  portfolio.                                                                     

· U.S. Government Issuer Risk. Treasury obligations may differ in their interest
  rates, maturities, times of issuance and other characteristics. Obligations of
  U.S. Government agencies and authorities are supported by varying degrees of   
  credit but generally are not backed by the full faith and credit of the U.S.   
  Government. No assurance can be given that the U.S. Government will provide    
  financial support to its agencies and authorities if it is not obligated by law
  to do so.

Performance

When the 2024 (1948-1952) Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements,acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2024 (b.1948-1952) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra Pension Reserve Fund 2016 (b. 1948-1952) (Prospectus Summary) | Symetra Pension Reserve Fund 2016 (b. 1948-1952)
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra Pension Reserve Fund - 2016 (b.1948-1952)
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra Pension Reserve Fund - 2016 (b.1948-1952) (the "2016 (1948-1952) Fund" or the "Fund") seeks investment returns that would provide an amount on the Fund's termination date approximately equal to the then present value of specified lifetime annuity payments to be made to investors born in the year range identified in the Fund's name. As a result of its investment objective, a Pension Reserve Fund may not be a wise investment choice for an investor who does not anticipate applying his or her accumulation to the purchase of a lifetime annuity on or shortly after the Fund's termination date.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the 2016 (1948-1952) Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The 2016 (1948-1952) Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" is an estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the 2016 (1948-1952) Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the 2016 (1948-1952) Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The 2016 (1948-1952) Fund invests primarily in government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the three highest categories by an NRSRO or unrated securities that the Sub-Adviser determines are of comparable quality. The Fund also may invest in other types of dollar-denominated investment debt grade securities, including money market instruments and securities of foreign issuers. Most of the securities held by the Fund are zero coupon debt securities. Under normal market conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the two highest categories by an NRSRO, and investing in other permitted investments when government securities and corporate securities in the two highest categories are not available in sufficient quantities at a reasonable price or are not available in optimal durations or maturities.  The Fund also may manage portfolio duration by investing in interest rate futures contracts, options on interest rate futures contracts, structured notes and entering into swap agreements, provided that structured notes and swap agreements are determined by the Sub-Adviser to pose minimal counter-party credit risk. The 2016 (1948-1952) Fund is managed to continuously meet portfolio duration targets that correspond to projected payments, based on actuarially determined survivorship rates, of a single life annuity on the life of a person born in the year-range identified in the Fund's name. The portfolio duration targets are recalculated at least monthly based on a formula established by the Adviser (after consultation with Symetra Life Insurance Company ("Symetra Life")) at the Fund's inception. The formula will not change once the Fund commences operations. (The only variables in the formula are the amount of time remaining until each annual projected payment of the single life annuity and the prevailing interest rates on the recalculation date. The prevailing interest rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet the Fund's daily portfolio duration target by first, to the extent that such investments are available, investing in securities having cash flows similar to the projected payments of the single life annuity and then by balancing investments in securities with longer and shorter durations than the target duration. The portfolio duration target generally declines for the Fund over the life of the Fund, but will be substantially greater than zero at the Fund's termination date. As a result, to meet the portfolio duration target, the Fund will likely have an investment portfolio at its termination date of debt securities of substantial remaining duration. This in turn, will result in the market value of the Fund's investment portfolio at the termination date being significantly influenced by prevailing interest rates. Generally speaking, the higher the prevailing rates at the Fund's maturity, the less the Fund will receive from selling its assets and the lower the prevailing rates, the more the Fund will receive for selling its assets. Thus, the market value of such assets is inversely related to prevailing interest rates. The present value of a future series of payments decreases as the interest rate on which the present value is computed increases. Therefore, on the 2016 (1948-1952) Fund's termination date the present value of the annuity payments the investor is entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund will be less the higher the prevailing interest rates. The Fund's adherence to the portfolio duration target formula is intended to result in the Fund having on its termination date net assets approximately equal to the present value of the aggregate annuity payments investors are entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund. However, even if a Fund successfully adheres to the formula, there is no guarantee that it will achieve this intended result or its investment objective. Although the Fund has no current plans to close, there is no guarantee that the Fund will continue to accept new investments until the termination date. As of the date of this Prospectus, based on the current U.S. Treasury Zero Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2016 (1948-1952) Fund's portfolio duration target would have been 15.5 years.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the 2016 (1948-1952) Fund. The following additional risks could affect the value of your investment: · Credit Risk. The issuers of the bonds and other debt securities held by the       2016 (1948-1952) Fund may not be able to make interest or principal payments      when due. Even if these issuers are able to make interest or principal            payments, changes in an issuer's credit rating or the market's perception of an   issuer's creditworthiness may also affect the value of the Fund's investment in   that issuer by leading to greater volatility in the price of the security.      · Credit Default Swap Risk. In a credit default swap transaction, both the 2016   (1948-1952) Fund and its counter-party are exposed to the risk of default by      the other. In addition, the terms of most credit default swap transactions        require little or no initial investment by the seller in relation to the          notional amount of the swap and the corresponding risk. Therefore, small          changes in the market value of the reference security or group of securities      may produce disproportionate and substantial losses for the seller.                · Derivatives Risk. Derivatives are securities, such as futures contracts, whose   value is derived from that of other securities or indices. The 2016 (1948-1952)   Fund's investments in derivatives may pose risks in addition to those             associated with investing directly in securities or other investments.            Derivative securities are subject to a number of risks including liquidity,       interest rate, market, credit and management risks, the risk of improper          valuation, illiquidity of the derivatives, imperfect correlations with            underlying investments or the Fund's other portfolio holdings, lack of            availability and counterparty risk. Changes in the value of the derivative may   not correlate perfectly with the underlying asset, rate or index, and the Fund   could lose more than the principal amount invested. An investment in              derivatives may not perform as anticipated by the Sub-Adviser, may not be able   to be closed out at a favorable time or price. An investment in derivatives may   also increase the Fund's volatility and create investment leverage. When a        derivative is used as a substitute or alternative to a direct cash investment,   the transaction may not provide a return that corresponds precisely with that     of the cash investment; or, when used for hedging purposes, derivatives may not   provide the anticipated protection, causing the Fund to lose money on both the   derivatives transaction and the exposure the Fund sought to hedge.              · Extension Risk. When interest rates rise, certain obligations will be paid off   by the obligor more slowly than anticipated, causing the value of these           securities to fall.                                                             · Foreign Investing Risk. The securities of foreign issuers may be less liquid      and more volatile than securities of comparable U.S. issuers. Investments in      securities of foreign issuers, even those publicly traded in the United States,   may involve risks which are in addition to those inherent in domestic             investments. Foreign companies may not be subject to the same regulatory          requirements of U.S. companies, and as a consequence, there may be less           publicly available information about such companies. Also, foreign companies      may not be subject to uniform accounting, auditing, and financial reporting       standards and requirements comparable to those applicable to U.S. companies.      Foreign governments and foreign economies often are less stable than the U.S.     Government and the U.S. economy.                                                · Interest Rate Risk. In general, the value of bonds and other debt securities      falls when interest rates rise. Generally, the longer the duration of a debt      security, the greater is the negative effect on its value when rates              increase. Because zero coupon debt securities do not pay interest, the market     value of such securities can fall more dramatically than interest-paying          securities of similar maturities when interest rates rise. While bonds and        other debt securities normally fluctuate less in price than common stocks,        there have been extended periods of increases in interest rates that have         caused significant declines in bond prices.                                     · Management Risk. The 2016 (1948-1952) Fund is subject to management risk          because it is an actively managed portfolio. The portfolio manager's management   practices, investment strategies, and choice of investments might not work to     produce the desired results and the Fund might underperform other comparable      funds.                                                                          · Market Risk. The prices of the securities in which the 2016 (1948-1952) Fund      invests may decline for a number of reasons including in response to economic     developments and perceptions about the creditworthiness of individual             issuers. Longer-term bonds, in which the Fund will invest a majority of its       assets, are generally more volatile.                                            · New Fund Risk. The 2016 (1948-1952) Fund is new with no operating history and     there can be no assurance that the Fund will grow to or maintain an               economically viable size. If the Fund does not grow to or maintain an             economically viable size the Board may consider various alternatives, including   the liquidation of the Fund or the merger of the Fund into another mutual fund.    · Portfolio Duration Target Formula Risk. There is no guarantee that adherence to   the portfolio duration target formula will result in the Fund achieving its       investment objective.                                                           · Prepayment Risk. When interest rates fall, certain obligations will be paid off   by the obligor more quickly than originally anticipated, and the 2016             (1948-1952) Fund may have to invest the proceeds in securities with lower         yields (this is known as Reinvestment Risk).                                    · Termination Risk. Because the 2016 (1948-1952) Fund has a Termination Date and   it will invest a majority of its assets in securities that mature after the       Termination Date, the Fund may incur liquidation costs to liquidate its           portfolio.                                                                      · U.S. Government Issuer Risk. Treasury obligations may differ in their interest   rates, maturities, times of issuance and other characteristics. Obligations of   U.S. Government agencies and authorities are supported by varying degrees of      credit but generally are not backed by the full faith and credit of the U.S.      Government. No assurance can be given that the U.S. Government will provide       financial support to its agencies and authorities if it is not obligated by law   to do so.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the 2016 (1948-1952) Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the 2016 (1948-1952) Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the 2016 (1948-1952) Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-SYMETRA (1-800-796-3872)
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra Pension Reserve Fund 2016 (b. 1948-1952) (Prospectus Summary) | Symetra Pension Reserve Fund 2016 (b. 1948-1952) | Symetra Pension Reserve Fund 2016 (b. 1948-1952)
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.32%
Other Expenses	rr_OtherExpensesOverAssets	1.77%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.09%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.69%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.40%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	41
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	491

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2016 (b.1948-1952) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra Pension Reserve Fund 2024 (b. 1953-1957) (Prospectus Summary) | Symetra Pension Reserve Fund 2024 (b. 1953-1957)
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra Pension Reserve Fund - 2024 (b.1953-1957)
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra Pension Reserve Fund - 2024 (b.1953-1957) (the "2024 (1953-1957) Fund" or the "Fund") seeks investment returns that would provide an amount on the Fund's termination date approximately equal to the then present value of specified lifetime annuity payments to be made to investors born in the year range identified in the Fund's name. As a result of its investment objective, a Pension Reserve Fund may not be a wise investment choice for an investor who does not anticipate applying his or her accumulation to the purchase of a lifetime annuity on or shortly after the Fund's termination date.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the 2024 (1953-1957) Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" is an estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the 2024 (1953-1957) Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The 2024 (1953-1957) Fund invests primarily in government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the three highest categories by an NRSRO or unrated securities that the Sub-Adviser determines are of comparable quality. The Fund also may invest in other types of dollar-denominated investment grade debt securities, including money market instruments and securities of foreign issuers. Most of the securities held by the Fund are zero coupon debt securities. Under normal market conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the two highest categories by an NRSRO, and investing in other permitted investments when government securities and corporate securities in the two highest categories are not available in sufficient quantities at a reasonable price or are not available in optimal durations or maturities.  The Fund also may manage portfolio duration by investing in interest rate futures contracts, options on interest rate futures contracts, structured notes and entering into swap agreements, provided that structured notes and swap agreements are determined by the Sub-Adviser to pose minimal counter-party credit risk. The 2024 (1953-1957) Fund is managed to continuously meet portfolio duration targets that correspond to projected payments, based on actuarially determined survivorship rates, of a single life annuity on the life of a person born in the year-range identified in the Fund's name. The portfolio duration targets are recalculated at least monthly based on a formula established by the Adviser (after consultation with Symetra Life Insurance Company ("Symetra Life")) at the Fund's inception. The formula will not change once the Fund commences operations. (The only variables in the formula are the amount of time remaining until each annual projected payment of the single life annuity and the prevailing interest rates on the recalculation date. The prevailing interest rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet the Fund's daily portfolio duration target by first, to the extent that such investments are available, investing in securities having cash flows similar to the projected payments of the single life annuity and then by balancing investments in securities with longer and shorter durations than the target duration. The portfolio duration target generally declines for the Fund over the life of the Fund, but will be substantially greater than zero at the Fund's termination date. As a result, to meet the portfolio duration target, the Fund will likely have an investment portfolio at its termination date of debt securities of substantial remaining duration. This in turn, will result in the market value of the Fund's investment portfolio at the termination date being significantly influenced by prevailing interest rates. Generally speaking, the higher the prevailing rates at the Fund's maturity, the less the Fund will receive from selling its assets and the lower the prevailing rates, the more the Fund will receive for selling its assets. Thus, the market value of such assets is inversely related to prevailing interest rates. The present value of a future series of payments decreases as the interest rate on which the present value is computed increases. Therefore, on the 2024 (1953-1957) Fund's termination date the present value of the annuity payments the investor is entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund will be less the higher the prevailing interest rates. The Fund's adherence to the portfolio duration target formula is intended to result in the Fund having on its termination date net assets approximately equal to the present value of the aggregate annuity payments investors are entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund. However, even if a Fund successfully adheres to the formula, there is no guarantee that it will achieve this intended result or its investment objective. Although the Fund has no current plans to close, there is no guarantee that the Fund will continue to accept new investments until the termination date. As of the date of this Prospectus, based on the current U.S. Treasury Zero Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2024 (1953-1957) Fund's portfolio duration target would have been 21.7 years.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the 2024 (1953-1957) Fund. The following additional risks could affect the value of your investment: · Credit Risk. The issuers of the bonds and other debt securities held by the       2024 (1953-1957) Fund may not be able to make interest or principal payments      when due. Even if these issuers are able to make interest or principal            payments, changes in an issuer's credit rating or the market's perception of an   issuer's creditworthiness may also affect the value of the Fund's investment in   that issuer by leading to greater volatility in the price of the security.         · Credit Default Swap Risk. In a credit default swap transaction, both the 2024   (1953-1957) Fund and its counter-party are exposed to the risk of default by      the other. In addition, the terms of most credit default swap transactions        require little or no initial investment by the seller in relation to the          notional amount of the swap and the corresponding risk. Therefore, small          changes in the market value of the reference security or group of securities      may produce disproportionate and substantial losses for the seller.             · Derivatives Risk. Derivatives are securities, such as futures contracts, whose   value is derived from that of other securities or indices. The 2024 (1953-1957)   Fund's investments in derivatives may pose risks in addition to those             associated with investing directly in securities or other investments.            Derivative securities are subject to a number of risks including liquidity,       interest rate, market, credit and management risks, the risk of improper          valuation, illiquidity of the derivatives, imperfect correlations with            underlying investments or the Fund's other portfolio holdings, lack of            availability and counterparty risk. Changes in the value of the derivative may   not correlate perfectly with the underlying asset, rate or index, and the Fund   could lose more than the principal amount invested. An investment in              derivatives may not perform as anticipated by the Sub-Adviser, may not be able   to be closed out at a favorable time or price. An investment in derivatives may   also increase the Fund's volatility and create investment leverage. When a        derivative is used as a substitute or alternative to a direct cash investment,   the transaction may not provide a return that corresponds precisely with that     of the cash investment; or, when used for hedging purposes, derivatives may not   provide the anticipated protection, causing the Fund to lose money on both the   derivatives transaction and the exposure the Fund sought to hedge.              · Extension Risk. When interest rates rise, certain obligations will be paid off   by the obligor more slowly than anticipated, causing the value of these           securities to fall.                                                             · Foreign Investing Risk. The securities of foreign issuers may be less liquid      and more volatile than securities of comparable U.S. issuers. Investments in      securities of foreign issuers, even those publicly traded in the United States,   may involve risks which are in addition to those inherent in domestic             investments. Foreign companies may not be subject to the same regulatory          requirements of U.S. companies, and as a consequence, there may be less           publicly available information about such companies. Also, foreign companies      may not be subject to uniform accounting, auditing, and financial reporting       standards and requirements comparable to those applicable to U.S. companies.      Foreign governments and foreign economies often are less stable than the U.S.     Government and the U.S. economy.                                                · Interest Rate Risk. In general, the value of bonds and other debt securities      falls when interest rates rise. Generally, the longer the duration of a debt      security, the greater is the negative effect on its value when rates              increase. Because zero coupon debt securities do not pay interest, the market     value of such securities can fall more dramatically than interest-paying          securities of similar maturities when interest rates rise. While bonds and        other debt securities normally fluctuate less in price than common stocks,        there have been extended periods of increases in interest rates that have         caused significant declines in bond prices.                                     · Management Risk. The 2024 (1953-1957) Fund is subject to management risk          because it is an actively managed portfolio. The portfolio manager's management   practices, investment strategies, and choice of investments might not work to     produce the desired results and the Fund might underperform other comparable      funds.                                                                          · Market Risk. The prices of the securities in which the 2024 (1953-1957) Fund      invests may decline for a number of reasons including in response to economic     developments and perceptions about the creditworthiness of individual             issuers. Longer-term bonds, in which the Fund will invest a majority of its       assets, are generally more volatile.                                            · New Fund Risk. The 2024 (1953-1957) Fund is new with no operating history and     there can be no assurance that the Fund will grow to or maintain an               economically viable size. If the Fund does not grow to or maintain an             economically viable size the Board may consider various alternatives, including   the liquidation of the Fund or the merger of the Fund into another mutual fund.    · Portfolio Duration Target Formula Risk. There is no guarantee that adherence to   the portfolio duration target formula will result in the Fund achieving its       investment objective.                                                           · Prepayment Risk. When interest rates fall, certain obligations will be paid off   by the obligor more quickly than originally anticipated, and the 2024             (1953-1957) Fund may have to invest the proceeds in securities with lower         yields (this is known as Reinvestment Risk).                                    · Termination Risk. Because the 2024 (1953-1957) Fund has a Termination Date and   it will invest a majority of its assets in securities that mature after the       Termination Date, the Fund may incur liquidation costs to liquidate its           portfolio.                                                                      · U.S. Government Issuer Risk. Treasury obligations may differ in their interest   rates, maturities, times of issuance and other characteristics. Obligations of   U.S. Government agencies and authorities are supported by varying degrees of      credit but generally are not backed by the full faith and credit of the U.S.      Government. No assurance can be given that the U.S. Government will provide       financial support to its agencies and authorities if it is not obligated by law   to do so.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the 2024 (1953-1957) Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the 2024 (1953-1957) Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the 2024 (1953-1957) Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-SYMETRA (1-800-796-3872)
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra Pension Reserve Fund 2024 (b. 1953-1957) (Prospectus Summary) | Symetra Pension Reserve Fund 2024 (b. 1953-1957) | Symetra Pension Reserve Fund 2024 (b. 1953-1957)
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.32%
Other Expenses	rr_OtherExpensesOverAssets	1.77%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.09%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.69%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.40%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	41
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	491

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2024 (b.1953-1957) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra DoubleLine Emerging Markets Income Fund (Prospectus Summary) | Symetra DoubleLine Emerging Markets Income Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra DoubleLine Emerging Markets Income Fund
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra DoubleLine Emerging Markets Income Fund (the "Emerging Markets Fund" or the "Fund") seeks total return through both income and capital appreciation.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Emerging Markets Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The Emerging Markets Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" is an estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Emerging Markets Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	Under normal market conditions the Emerging Markets Fund pursues its investment objective by investing at least 80% of its net assets (plus the amount of borrowings for investment purposes) in debt securities of foreign issuers that are located in emerging market countries or whose securities are traded in emerging markets. The Fund generally maintains investments in securities of issuers in at least four emerging market countries. Nonetheless, the Fund is not a diversified mutual fund under the 1940 Act. In allocating investments among various emerging market countries, the Fund's Sub-Adviser attempts to analyze various internal economic, market and political factors, including the following: (1) public finance, (2) monetary policy, (3) external accounts, (4) financial markets, (5) regulation of foreign investments, (6) exchange rate policy, and (7) labor conditions. An emerging market country is a country that, at the time the Emerging Markets Fund invests in the related debt instruments, is classified as an emerging or developing economy by any supranational organization such as the World Bank or the United Nations, or related entities, or is considered an emerging market country for purposes of constructing major emerging market securities indexes. The Emerging Markets Fund may invest without limitation in lower-rated securities, commonly known as junk bonds, and may invest up to 20% of its assets in defaulted corporate securities when the Sub-Adviser believes that the restructured enterprise valuation or liquidation valuation may significantly exceed current market valuations. In addition, the Fund may invest in defaulted foreign government debt securities where the Sub-Adviser believes that the expected debt sustainability of the country exceeds current market valuations. In order to hedge the Fund's portfolio, as well as for investment purposes, the Fund may purchase or sell options on securities in which it may invest and invest in interest rate futures contracts, options on interest rate futures contracts, structured notes, foreign currency futures contracts, foreign currency forward contracts and enter into swap agreements (including credit default swaps). Under normal market conditions, the Emerging Markets Fund generally seeks a target weighted average effective duration of two to eight years, though actual duration may vary considerably from this target. Portfolio securities may be sold at any time. Sales may occur when the Emerging Markets Fund's portfolio manager perceives deterioration in the credit fundamentals of the issuer, the portfolio manager believes there are negative macro geo-political considerations that may affect the issuer, the portfolio manager determines to take advantage of a better investment opportunity or the individual security has reached the portfolio manager's sell target.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the Emerging Markets Fund. The following additional risks could affect the value of your investment: · Active Trading Risk. Active trading, also called "high portfolio turnover," may   result in higher brokerage costs or mark-up charges, as compared to a fund that   trades less frequently, which may negatively affect Fund performance.              · Credit Risk. The issuers of the bonds and other debt securities held by the       Emerging Markets Fund may not be able to make interest or principal payments      when due. Even if these issuers are able to make interest or principal            payments, changes in an issuer's credit rating or the market's perception of an   issuer's creditworthiness may also affect the value of the Fund's investment in   that issuer by leading to greater volatility in the price of the security.         · Defaulted Securities Risk. There is a high level of uncertainty regarding the     repayment of defaulted securities and obligations of distressed issuers.        · Derivatives Risk.  Derivatives are securities, such as futures contracts, whose   values are derived from those of other securities or indices. The Emerging        Markets Fund's investments in derivatives may pose risks in addition to those     associated with investing directly in securities or other investments.            Derivative securities are subject to a number of risks including liquidity,       interest rate, market, credit and management risks, the risk of improper          valuation, illiquidity of the derivatives, imperfect correlations with            underlying investments or the Fund's other portfolio holdings, lack of            availability and counterparty risk. Changes in the value of the derivative may   not correlate perfectly with the underlying asset, rate or index, and the Fund   could lose more than the principal amount invested. An investment in              derivatives may not perform as anticipated by the Sub-Adviser, may not be able   to be closed out at a favorable time or price. An investment in derivatives may   also increase the Fund's volatility and create investment leverage. When a        derivative is used as a substitute or alternative to a direct cash investment,   the transaction may not provide a return that corresponds precisely with that     of the cash investment; or, when used for hedging purposes, derivatives may not   provide the anticipated protection, causing the Fund to lose money on both the   derivatives transaction and the exposure the Fund sought to hedge.              · Foreign Investing Risk. The securities of foreign issuers may be less liquid      and more volatile than securities of comparable U.S. issuers. The costs           associated with securities transactions are often higher in foreign countries     than the U.S. The U.S. dollar value of securities of foreign issuers traded in   foreign currencies (and any dividends and interest earned) held by the Emerging   Markets Fund may be affected favorably or unfavorably by changes in foreign       currency exchange rates. An increase in the U.S. dollar relative to these other   currencies will adversely affect the Fund (this is known as Foreign Currency      Risk). The Fund does not hedge foreign currency risk. Additionally, investments   in securities of foreign issuers, even those publicly traded in the United        States, may involve risks which are in addition to those inherent in domestic     investments. Foreign companies may not be subject to the same regulatory          requirements of U.S. companies, and as a consequence, there may be less           publicly available information about such companies. Also, foreign companies      may not be subject to uniform accounting, auditing, and financial reporting       standards and requirements comparable to those applicable to U.S. companies.      Foreign governments and foreign economies often are less stable than the U.S.     Government and the U.S. economy. These risks are magnified for emerging markets   countries (Emerging Market Country Risk) due to the greater degree of economic,   political and social instability of emerging market countries as compared to      developed countries.                                                            · Interest Rate Risk. In general, the value of bonds and other debt securities      falls when interest rates rise. Generally, the longer the duration of a debt      security, the greater is the negative effect on its value when rates              increase. While bonds and other debt securities normally fluctuate less in        price than common stocks, there have been extended periods of increases in        interest rates that have caused significant declines in bond prices.               · Junk Bond Risk. Although junk bonds generally pay higher rates of interest than   investment grade bonds, junk bonds are high risk investments that may cause       income and principal losses for the Emerging Markets Fund. Junk bonds are         subject to reduced creditworthiness of issuers; increased risk of default and a   more limited and less liquid secondary market than higher rated securities; and   greater price volatility and risk of loss of income and principal than are        higher rated securities.                                                           · Leveraging Risk. Certain investments by the Emerging Markets Fund may involve     leverage, which may have the effect of increasing the volatility of the Fund's   portfolio, and the risk of loss in excess of invested capital.                     · Liquidity Risk. In certain circumstances, low trading volume, lack of a market   maker, or contractual or legal restrictions may limit or prevent the Emerging     Markets Fund from selling securities or closing any derivative positions within   a reasonable time at desirable prices. In addition, the ability of the Fund to   assign an accurate daily value to certain investments may be difficult, and the   Adviser may be required to fair value the investments.                             · Management Risk. The Emerging Markets Fund is subject to management risk          because it is an actively managed portfolio. The portfolio manager's management   practices, investment strategies, and choice of investments might not work to     produce the desired results and the Fund might underperform other comparable      funds.                                                                             · Market Risk. The prices of the securities in which the Emerging Markets Fund      invests may decline for a number of reasons including in response to economic     or political developments and perceptions about the creditworthiness of           individual issuers or other issuer-specific events.                                · New Fund Risk. The Emerging Markets Fund is new with no operating history and     there can be no assurance that the Fund will grow to or maintain an               economically viable size. If the Fund does not grow to or maintain an             economically viable size, the Board may consider various alternatives,            including the liquidation of the Fund or the merger of the Fund into another      mutual fund.                                                                    · Non-diversification Risk. The Emerging Markets Fund is a non-diversified          investment company. As such, it will likely invest in fewer securities than       diversified investment companies and its performance may be more volatile. The   Fund may be more susceptible to any single economic, political or regulatory      event than a more diversified fund. If the securities in which the Fund invests   perform poorly, the Fund could incur greater losses than it would have had it     invested in a greater number of securities.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the Emerging Markets Fund.
Risk, Nondiversified Status	rr_RiskNondiversifiedStatus	The Emerging Markets Fund is a non-diversified investment company. As such, it will likely invest in fewer securities than diversified investment companies and its performance may be more volatile. The Fund may be more susceptible to any single economic, political or regulatory event than a more diversified fund. If the securities in which the Fund invests perform poorly, the Fund could incur greater losses than it would have had it invested in a greater number of securities.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the Emerging Markets Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the Emerging Markets Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-SYMETRA (1-800-796-3872)
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra DoubleLine Emerging Markets Income Fund (Prospectus Summary) | Symetra DoubleLine Emerging Markets Income Fund | Symetra DoubleLine Emerging Markets Income Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.90%
Other Expenses	rr_OtherExpensesOverAssets	1.48%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.38%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.40%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.98%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	100
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	608

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Emerging Markets Income Fund (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Symetra Pension Reserve Fund 2028 (b. 1953-1957) (Prospectus Summary) | Symetra Pension Reserve Fund 2028 (b. 1953-1957)

Symetra Pension Reserve Fund - 2028 (b.1953-1957)

Investment Objective

The Symetra Pension Reserve Fund - 2028 (b.1953-1957) (the "2028 (1953-1957)
Fund" or the "Fund") seeks investment returns that would provide an amount on
the Fund's termination date approximately equal to the then present value of
specified lifetime annuity payments to be made to investors born in the year
range identified in the Fund's name. As a result of its investment objective,
a Pension Reserve Fund may not be a wise investment choice for an investor who
does not anticipate applying his or her accumulation to the purchase of a
lifetime annuity on or shortly after the Fund's termination date.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the 2028 (1953-1957) Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity or variable life insurance contract level. If
those additional fees and expenses were included, overall expenses would be
higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra Pension Reserve Fund 2028 (b. 1953-1957)
Management Fees		0.32%
Other Expenses	[1]	1.77%
Total Annual Fund Operating Expenses		2.09%
Less: Fee Waiver and Expense Reimbursement	[2]	(1.69%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.40%

Example

This Example is intended to help you compare the cost of investing in the 2028
(1953-1957) Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated and
then redeem all of your shares at the end of those periods. The Example also
assumes that your investment has a 5% return each year and that the Fund's
operating expenses remain the same (taking into account the Expense Cap and Fee
Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra Pension Reserve Fund 2028 (b. 1953-1957)	41	491

Portfolio Turnover

The 2028 (1953-1957) Fund pays transaction costs, such as commissions, when it
buys and sells securities (or "turns over" its portfolio). A higher portfolio
turnover rate may indicate higher transaction costs and may result in higher
taxes when Fund shares are held in a taxable account. These costs, which are not
reflected in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Fund

The 2028 (1953-1957) Fund invests primarily in government securities and
dollar-denominated corporate debt securities rated, at the time of purchase,
in the three highest categories by an NRSRO or unrated securities that the
Sub-Adviser determines are of comparable quality. The Fund also may invest in
other types of dollar-denominated investment grade debt securities, including
money market instruments and securities of foreign issuers. Most of the
securities held by the Fund are zero coupon debt securities. Under normal market
conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring
government securities and dollar-denominated corporate debt securities rated, at
the time of purchase, in the two highest categories by an NRSRO, and investing
in other permitted investments when government securities and corporate
securities in the two highest categories are not available in sufficient
quantities at a reasonable price or are not available in optimal durations or
maturities.  The Fund also may manage portfolio duration by investing in
interest rate futures contracts, options on interest rate futures contracts,
structured notes and entering into swap agreements, provided that structured
notes and swap agreements are determined by the Sub-Adviser to pose minimal
counter-party credit risk.

The 2028 (1953-1957) Fund is managed to continuously meet portfolio duration
targets that correspond to projected payments, based on actuarially determined
survivorship rates, of a single life annuity on the life of a person born in the
year-range identified in the Fund's name. The portfolio duration targets are
recalculated at least monthly based on a formula established by the Adviser
(after consultation with Symetra Life Insurance Company ("Symetra Life")) at the
Fund's inception. The formula will not change once the Fund commences operations.
(The only variables in the formula are the amount of time remaining until each
annual projected payment of the single life annuity and the prevailing interest
rates on the recalculation date. The prevailing interest rates are derived from
the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under
normal market conditions, the Sub-Adviser seeks to meet the Fund's daily
portfolio duration target by first, to the extent that such investments are
available, investing in securities having cash flows similar to the projected
payments of the single life annuity and then by balancing investments in
securities with longer and shorter durations than the target duration. The
portfolio duration target generally declines for the Fund over the life of the
Fund, but will be substantially greater than zero at the Fund's termination date.
As a result, to meet the portfolio duration target, the Fund will likely have an
investment portfolio at its termination date of debt securities of substantial
remaining duration. This in turn, will result in the market value of the Fund's
investment portfolio at the termination date being significantly influenced by
prevailing interest rates. Generally speaking, the higher the prevailing rates
at the Fund's maturity, the less the Fund will receive from selling its assets
and the lower the prevailing rates, the more the Fund will receive for selling
its assets. Thus, the market value of such assets is inversely related to
prevailing interest rates.

The present value of a future series of payments decreases as the interest rate
on which the present value is computed increases. Therefore, on the 2028
(1953-1957) Fund's termination date the present value of the annuity payments
the investor is entitled to receive as a result of owning accumulation units in
the sub-account of the Symetra Resource Variable Account B that invests in
shares of the Fund will be less the higher the prevailing interest rates. The
Fund's adherence to the portfolio duration target formula is intended to result
in the Fund having on its termination date net assets approximately equal to the
present value of the aggregate annuity payments investors are entitled to
receive as a result of owning accumulation units in the sub-account of the
Symetra Resource Variable Account B that invests in shares of the Fund. However,
even if a Fund successfully adheres to the formula, there is no guarantee that
it will achieve this intended result or its investment objective. Although the
Fund has no current plans to close, there is no guarantee that the Fund will
continue to accept new investments until the termination date.

As of the date of this Prospectus, based on the current U.S. Treasury Zero
Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2028
(1953-1957) Fund's portfolio duration target would have been 23.9 years.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the 2028
(1953-1957) Fund. The following additional risks could affect the value of your
investment:

· Credit Risk. The issuers of the bonds and other debt securities held by the    
  2028 (1953-1957) Fund may not be able to make interest or principal payments   
  when due. Even if these issuers are able to make interest or principal         
  payments, changes in an issuer's credit rating or the market's perception of an
  issuer's creditworthiness may also affect the value of the Fund's investment in
  that issuer by leading to greater volatility in the price of the security.     
  
· Credit Default Swap Risk. In a credit default swap transaction, both the 2028
  (1953-1957) Fund and its counter-party are exposed to the risk of default by   
  the other. In addition, the terms of most credit default swap transactions     
  require little or no initial investment by the seller in relation to the       
  notional amount of the swap and the corresponding risk. Therefore, small       
  changes in the market value of the reference security or group of securities   
  may produce disproportionate and substantial losses for the seller.            

· Derivatives Risk. Derivatives are securities, such as futures contracts, whose
  value is derived from that of other securities or indices. The 2028 (1953-1957)
  Fund's investments in derivatives may pose risks in addition to those          
  associated with investing directly in securities or other investments.         
  Derivative securities are subject to a number of risks including liquidity,    
  interest rate, market, credit and management risks, the risk of improper       
  valuation, illiquidity of the derivatives, imperfect correlations with         
  underlying investments or the Fund's other portfolio holdings, lack of         
  availability and counterparty risk. Changes in the value of the derivative may
  not correlate perfectly with the underlying asset, rate or index, and the Fund
  could lose more than the principal amount invested. An investment in           
  derivatives may not perform as anticipated by the Sub-Adviser, may not be able
  to be closed out at a favorable time or price. An investment in derivatives may
  also increase the Fund's volatility and create investment leverage. When a     
  derivative is used as a substitute or alternative to a direct cash investment,
  the transaction may not provide a return that corresponds precisely with that  
  of the cash investment; or, when used for hedging purposes, derivatives may not
  provide the anticipated protection, causing the Fund to lose money on both the
  derivatives transaction and the exposure the Fund sought to hedge.             

· Extension Risk. When interest rates rise, certain obligations will be paid off
  by the obligor more slowly than anticipated, causing the value of these        
  securities to fall.                                                            

· Foreign Investing Risk. The securities of foreign issuers may be less liquid   
  and more volatile than securities of comparable U.S. issuers. Investments in   
  securities of foreign issuers, even those publicly traded in the United States,
  may involve risks which are in addition to those inherent in domestic          
  investments. Foreign companies may not be subject to the same regulatory       
  requirements of U.S. companies, and as a consequence, there may be less        
  publicly available information about such companies. Also, foreign companies   
  may not be subject to uniform accounting, auditing, and financial reporting    
  standards and requirements comparable to those applicable to U.S. companies.   
  Foreign governments and foreign economies often are less stable than the U.S.  
  Government and the U.S. economy.                                               

· Interest Rate Risk. In general, the value of bonds and other debt securities   
  falls when interest rates rise. Generally, the longer the duration of a debt   
  security, the greater is the negative effect on its value when rates           
  increase. Because zero coupon debt securities do not pay interest, the market  
  value of such securities can fall more dramatically than interest-paying       
  securities of similar maturities when interest rates rise. While bonds and     
  other debt securities normally fluctuate less in price than common stocks,     
  there have been extended periods of increases in interest rates that have      
  caused significant declines in bond prices.                                    

· Management Risk. The 2028 (1953-1957) Fund is subject to management risk       
  because it is an actively managed portfolio. The portfolio manager's management
  practices, investment strategies, and choice of investments might not work to  
  produce the desired results and the Fund might underperform other comparable   
  funds.                                                                         

· Market Risk. The prices of the securities in which the 2028 (1953-1957) Fund   
  invests may decline for a number of reasons including in response to economic  
  developments and perceptions about the creditworthiness of individual          
  issuers. Longer-term bonds, in which the Fund will invest a majority of its    
  assets, are generally more volatile.                                           

· New Fund Risk. The 2028 (1953-1957) Fund is new with no operating history and  
  there can be no assurance that the Fund will grow to or maintain an            
  economically viable size. If the Fund does not grow to or maintain an          
  economically viable size the Board may consider various alternatives, including
  the liquidation of the Fund or the merger of the Fund into another mutual fund.
  
· Portfolio Duration Target Formula Risk. There is no guarantee that adherence to
  the portfolio duration target formula will result in the Fund achieving its    
  investment objective.                                                          

· Prepayment Risk. When interest rates fall, certain obligations will be paid off
  by the obligor more quickly than originally anticipated, and the 2028          
  (1953-1957) Fund may have to invest the proceeds in securities with lower      
  yields (this is known as Reinvestment Risk).                                   

· Termination Risk. Because the 2028 (1953-1957) Fund has a Termination Date and
  it will invest a majority of its assets in securities that mature after the    
  Termination Date, the Fund may incur liquidation costs to liquidate its        
  portfolio.                                                                     

· U.S. Government Issuer Risk. Treasury obligations may differ in their interest
  rates, maturities, times of issuance and other characteristics. Obligations of
  U.S. Government agencies and authorities are supported by varying degrees of   
  credit but generally are not backed by the full faith and credit of the U.S.   
  Government. No assurance can be given that the U.S. Government will provide    
  financial support to its agencies and authorities if it is not obligated by law
  to do so.

Performance

When the 2028 (1953-1957) Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2028 (b.1953-1957) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra Pension Reserve Fund 2020 (b. 1942-1947) (Prospectus Summary) | Symetra Pension Reserve Fund 2020 (b. 1942-1947)
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra Pension Reserve Fund - 2020 (b.1942-1947)
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra Pension Reserve Fund - 2020 (b.1942-1947) (the "2020 (1942-1947) Fund" or the "Fund") seeks investment returns that would provide an amount on the Fund's termination date approximately equal to the then present value of specified lifetime annuity payments to be made to investors born in the year range identified in the Fund's name. As a result of its investment objective, a Pension Reserve Fund may not be a wise investment choice for an investor who does not anticipate applying his or her accumulation to the purchase of a lifetime annuity on or shortly after the Fund's termination date.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the 2020 (1942-1947) Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The 2020 (1942-1947) Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" is an estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the 2020 (1942-1947) Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The 2020 (1942-1947) Fund invests primarily in government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the three highest categories by an NRSRO or unrated securities that the Sub-Adviser determines are of comparable quality. The Fund also may invest in other types of dollar-denominated investment grade debt securities, including money market instruments and securities of foreign issuers. Most of the securities held by the Fund are zero coupon debt securities. Under normal market conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the two highest categories by an NRSRO, and investing in other permitted investments when government securities and corporate securities in the two highest categories are not available in sufficient quantities at a reasonable price or are not available in optimal durations or maturities.  The Fund also may manage portfolio duration by investing in interest rate futures contracts, options on interest rate futures contracts, structured notes and entering into swap agreements, provided that structured notes and swap agreements are determined by the Sub-Adviser to pose minimal counter-party credit risk. The 2020 (1942-1947) Fund is managed to continuously meet portfolio duration targets that correspond to projected payments, based on actuarially determined survivorship rates, of a single life annuity on the life of a person born in the year-range identified in the Fund's name. The portfolio duration targets are recalculated at least monthly based on a formula established by the Adviser (after consultation with Symetra Life Insurance Company ("Symetra Life")) at the Fund's inception. The formula will not change once the Fund commences operations. (The only variables in the formula are the amount of time remaining until each annual projected payment of the single life annuity and the prevailing interest rates on the recalculation date. The prevailing interest rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet the Fund's daily portfolio duration target by first, to the extent that such investments are available, investing in securities having cash flows similar to the projected payments of the single life annuity and then by balancing investments in securities with longer and shorter durations than the target duration. The portfolio duration target generally declines for the Fund over the life of the Fund, but will be substantially greater than zero at the Fund's termination date. As a result, to meet the portfolio duration target, the Fund will have an investment portfolio at its termination date of debt securities of substantial remaining duration. This in turn, will result in the market value of the Fund's investment portfolio at the termination date being significantly influenced by prevailing interest rates. Generally speaking, the higher the prevailing rates at the Fund's maturity, the less the Fund will receive from selling its assets and the lower the prevailing rates, the more the Fund will receive for selling its assets. Thus, the market value of such assets is inversely related to prevailing interest rates. The present value of a future series of payments decreases as the interest rate on which the present value is computed increases. Therefore, on the 2020 (1942-1947) Fund's termination date the present value of the annuity payments the investor is entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund will be less the higher the prevailing interest rates. The Fund's adherence to the portfolio duration target formula is intended to result in the Fund having on its termination date net assets approximately equal to the present value of the aggregate annuity payments investors are entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund. However, even if a Fund successfully adheres to the formula, there is no guarantee that it will achieve this intended result or its investment objective. Although the Fund has no current plans to close, there is no guarantee that the Fund will continue to accept new investments until the termination date. As of the date of this Prospectus, based on the current U.S. Treasury Zero Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2020 (1942-1947) Fund's portfolio duration target would have been 16.2 years.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the 2020 (1942-1947) Fund. The following additional risks could affect the value of your investment: · Credit Risk. The issuers of the bonds and other debt securities held by the     2020 (1942-1947) Fund may not be able to make interest or principal payments   when due. Even if these issuers are able to make interest or principal          payments, changes in an issuer's credit rating or the market's perception of   an issuer's creditworthiness may also affect the value of the Fund's            investment in that issuer by leading to greater volatility in the price of      the security.                                                                    · Credit Default Swap Risk. In a credit default swap transaction, both the 2020   (1942-1947) Fund and its counter-party are exposed to the risk of default by      the other. In addition, the terms of most credit default swap transactions        require little or no initial investment by the seller in relation to the          notional amount of the swap and the corresponding risk. Therefore, small          changes in the market value of the reference security or group of securities      may produce disproportionate and substantial losses for the seller.                · Derivatives Risk. Derivatives are securities, such as futures contracts, whose   value is derived from that of other securities or indices. The 2020 (1942-1947)   Fund's investments in derivatives may pose risks in addition to those             associated with investing directly in securities or other investments.            Derivative securities are subject to a number of risks including liquidity,       interest rate, market, credit and management risks, the risk of improper          valuation, illiquidity of the derivatives, imperfect correlations with            underlying investments or the Fund's other portfolio holdings, lack of            availability and counterparty risk. Changes in the value of the derivative may   not correlate perfectly with the underlying asset, rate or index, and the Fund   could lose more than the principal amount invested. An investment in              derivatives may not perform as anticipated by the Sub-Adviser, may not be able   to be closed out at a favorable time or price. An investment in derivatives may   also increase the Fund's volatility and create investment leverage. When a        derivative is used as a substitute or alternative to a direct cash investment,   the transaction may not provide a return that corresponds precisely with that     of the cash investment; or, when used for hedging purposes, derivatives may not   provide the anticipated protection, causing the Fund to lose money on both the   derivatives transaction and the exposure the Fund sought to hedge.                 · Extension Risk. When interest rates rise, certain obligations will be paid off   by the obligor more slowly than anticipated, causing the value of these           securities to fall.                                                                · Foreign Investing Risk. The securities of foreign issuers may be less liquid      and more volatile than securities of comparable U.S. issuers. Investments in      securities of foreign issuers, even those publicly traded in the United States,   may involve risks which are in addition to those inherent in domestic             investments. Foreign companies may not be subject to the same regulatory          requirements of U.S. companies, and as a consequence, there may be less           publicly available information about such companies. Also, foreign companies      may not be subject to uniform accounting, auditing, and financial reporting       standards and requirements comparable to those applicable to U.S. companies.      Foreign governments and foreign economies often are less stable than the U.S.     Government and the U.S. economy.                                                   · Interest Rate Risk. In general, the value of bonds and other debt securities      falls when interest rates rise. Generally, the longer the duration of a debt      security, the greater is the negative effect on its value when rates              increase. Because zero coupon debt securities do not pay interest, the market     value of such securities can fall more dramatically than interest-paying          securities of similar maturities when interest rates rise. While bonds and        other debt securities normally fluctuate less in price than common stocks,        there have been extended periods of increases in interest rates that have         caused significant declines in bond prices.                                        · Management Risk. The 2020 (1942-1947) Fund is subject to management risk          because it is an actively managed portfolio. The portfolio manager's management   practices, investment strategies, and choice of investments might not work to     produce the desired results and the Fund might underperform other comparable      funds.                                                                             · Market Risk. The prices of the securities in which the 2020 (1942-1947) Fund      invests may decline for a number of reasons including in response to economic     developments and perceptions about the creditworthiness of individual             issuers. Longer-term bonds, in which the Fund will invest a majority of its       assets, are generally more volatile.                                               · New Fund Risk. The 2020 (1942-1947) Fund is new with no operating history and     there can be no assurance that the Fund will grow to or maintain an               economically viable size. If the Fund does not grow to or maintain an             economically viable size the Board may consider various alternatives, including   the liquidation of the Fund or the merger of the Fund into another mutual fund.    · Portfolio Duration Target Formula Risk. There is no guarantee that adherence to   the portfolio duration target formula will result in the Fund achieving its       investment objective.                                                              · Prepayment Risk. When interest rates fall, certain obligations will be paid off   by the obligor more quickly than originally anticipated, and the 2020             (1942-1947) Fund may have to invest the proceeds in securities with lower         yields (this is known as Reinvestment Risk).                                       · Termination Risk. Because the 2020 (1942-1947) Fund has a Termination Date and   it will invest a majority of its assets in securities that mature after the       Termination Date, the Fund may incur liquidation costs to liquidate its           portfolio.                                                                         · U.S. Government Issuer Risk. Treasury obligations may differ in their interest   rates, maturities, times of issuance and other characteristics. Obligations of   U.S. Government agencies and authorities are supported by varying degrees of      credit but generally are not backed by the full faith and credit of the U.S.      Government. No assurance can be given that the U.S. Government will provide       financial support to its agencies and authorities if it is not obligated by law   to do so.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the 2020 (1942-1947) Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the 2020 (1942-1947) Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the 2020 (1942-1947) Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-SYMETRA (1-800-796-3872)
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra Pension Reserve Fund 2020 (b. 1942-1947) (Prospectus Summary) | Symetra Pension Reserve Fund 2020 (b. 1942-1947) | Symetra Pension Reserve Fund 2020 (b. 1942-1947)
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.32%
Other Expenses	rr_OtherExpensesOverAssets	1.77%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.09%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.69%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.40%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	41
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	491

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2020 (b. 1942-1947) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Symetra Pension Reserve Fund 2024 (b. 1942-1947) (Prospectus Summary) | Symetra Pension Reserve Fund 2024 (b. 1942-1947)

Symetra Pension Reserve Fund - 2024 (b.1942-1947)

Investment Objective

The Symetra Pension Reserve Fund - 2024 (b.1942-1947) (the "2024 (1942-1947)
Fund" or the "Fund") seeks investment returns that would provide an amount on
the Fund's termination date approximately equal to the then present value of
specified lifetime annuity payments to be made to investors born in the year
range identified in the Fund's name. As a result of its investment objective, a
Pension Reserve Fund may not be a wise investment choice for an investor who
does not anticipate applying his or her accumulation to the purchase of a
lifetime annuity on or shortly after the Fund's termination date.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the 2024 (1942-1947) Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity or variable life insurance contract level. If
those additional fees and expenses were included, overall expenses would be
higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra Pension Reserve Fund 2024 (b. 1942-1947)
Management Fees		0.32%
Other Expenses	[1]	1.77%
Total Annual Fund Operating Expenses		2.09%
Less: Fee Waiver and Expense Reimbursement	[2]	(1.69%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.40%

Example

This Example is intended to help you compare the cost of investing in the 2024
(1942-1947) Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated and
then redeem all of your shares at the end of those periods. The Example also
assumes that your investment has a 5% return each year and that the Fund's
operating expenses remain the same (taking into account the Expense Cap and Fee
Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra Pension Reserve Fund 2024 (b. 1942-1947)	41	491

Portfolio Turnover

The 2024 (1942-1947) Fund pays transaction costs, such as commissions, when it
buys and sells securities (or "turns over" its portfolio). A higher portfolio
turnover rate may indicate higher transaction costs and may result in higher
taxes when Fund shares are held in a taxable account. These costs, which are not
reflected in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Fund

The 2024 (1942-1947) Fund invests primarily in government securities and
dollar-denominated corporate debt securities rated, at the time of purchase, in
the three highest categories by an NRSRO or unrated securities that the
Sub-Adviser determines are of comparable quality. The Fund also may invest in
other types of dollar-denominated investment grade debt securities, including
money market instruments and securities of foreign issuers. Most of the
securities held by the Fund are zero coupon debt securities. Under normal market
conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring
government securities and dollar-denominated corporate debt securities rated, at
the time of purchase, in the two highest categories by an NRSRO, and investing
in other permitted investments when government securities and corporate
securities in the two highest categories are not available in sufficient
quantities at a reasonable price or are not available in optimal durations or
maturities.  The Fund also may manage portfolio duration by investing in
interest rate futures contracts, options on interest rate futures contracts,
structured notes and entering into swap agreements, provided that structured
notes and swap agreements are determined by the Sub-Adviser to pose minimal
counter-party credit risk.

The 2024 (1942-1947) Fund is managed to continuously meet portfolio duration
targets that correspond to projected payments, based on actuarially determined
survivorship rates, of a single life annuity on the life of a person born in the
year-range identified in the Fund's name. The portfolio duration targets are
recalculated at least monthly based on a formula established by the Adviser
(after consultation with Symetra Life Insurance Company ("Symetra Life")) at the
Fund's inception. The formula will not change once the Fund commences
operations. (The only variables in the formula are the amount of time remaining
until each annual projected payment of the single life annuity and the
prevailing interest rates on the recalculation date. The prevailing interest
rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by
interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet
the Fund's daily portfolio duration target by first, to the extent that such
investments are available, investing in securities having cash flows similar to
the projected payments of the single life annuity and then by balancing
investments in securities with longer and shorter durations than the target
duration. The portfolio duration target generally declines for the Fund over the
life of the Fund, but will be substantially greater than zero at the Fund's
termination date. As a result, to meet the portfolio duration target, the Fund
will likely have an investment portfolio at its termination date of debt
securities of substantial remaining duration. This in turn, will result in the
market value of the Fund's investment portfolio at the termination date being
significantly influenced by prevailing interest rates. Generally speaking, the
higher the prevailing rates at the Fund's maturity, the less the Fund will
receive from selling its assets and the lower the prevailing rates, the more the
Fund will receive for selling its assets. Thus, the market value of such assets
is inversely related to prevailing interest rates.

The present value of a future series of payments decreases as the interest rate
on which the present value is computed increases. Therefore, on the 2024
(1942-1947) Fund's termination date the present value of the annuity payments
the investor is entitled to receive as a result of owning accumulation units in
the sub-account of the Symetra Resource Variable Account B that invests in
shares of the Fund will be less the higher the prevailing interest rates. The
Fund's adherence to the portfolio duration target formula is intended to result
in the Fund having on its termination date net assets approximately equal to the
present value of the aggregate annuity payments investors are entitled to
receive as a result of owning accumulation units in the sub-account of the
Symetra Resource Variable Account B that invests in shares of the Fund. However,
even if a Fund successfully adheres to the formula, there is no guarantee that
it will achieve this intended result or its investment objective. Although the
Fund has no current plans to close, there is no guarantee that the Fund will
continue to accept new investments until the termination date.

As of the date of this Prospectus, based on the current U.S. Treasury Zero
Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2024
(1942-1947) Fund's portfolio duration target would have been 18.5 years.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the 2024
(1942-1947) Fund. The following additional risks could affect the value of your
investment:

· Credit Risk. The issuers of the bonds and other debt securities held by the    
  2024 (1942-1947) Fund may not be able to make interest or principal payments   
  when due. Even if these issuers are able to make interest or principal         
  payments, changes in an issuer's credit rating or the market's perception of an
  issuer's creditworthiness may also affect the value of the Fund's investment in
  that issuer by leading to greater volatility in the price of the security.     

· Credit Default Swap Risk.  In a credit default swap transaction, both the 2024
  (1942-1947) Fund and its counter-party are exposed to the risk of default by   
  the other. In addition, the terms of most credit default swap transactions     
  require little or no initial investment by the seller in relation to the       
  notional amount of the swap and the corresponding risk. Therefore, small       
  changes in the market value of the reference security or group of securities   
  may produce disproportionate and substantial losses for the seller.            
  
· Derivatives Risk. Derivatives are securities, such as futures contracts, whose
  value is derived from that of other securities or indices. The Fund's          
  investments in derivatives may pose risks in addition to those associated with
  investing directly in securities or other investments. Derivative securities   
  are subject to a number of risks including liquidity, interest rate, market,   
  credit and management risks, the risk of improper valuation, illiquidity of the
  derivatives, imperfect correlations with underlying investments or the Fund's  
  other portfolio holdings, lack of availability and counterparty risk. Changes  
  in the value of the derivative may not correlate perfectly with the underlying
  asset, rate or index, and the Fund could lose more than the principal amount   
  invested. An investment in derivatives may not perform as anticipated by the   
  Sub-Adviser, may not be able to be closed out at a favorable time or price. An
  investment in derivatives may also increase the Fund's volatility and create   
  investment leverage. When a derivative is used as a substitute or alternative  
  to a direct cash investment, the transaction may not provide a return that     
  corresponds precisely with that of the cash investment; or, when used for      
  hedging purposes, derivatives may not provide the anticipated protection,      
  causing the Fund to lose money on both the derivatives transaction and the     
  exposure the Fund sought to hedge.                                             
  
· Extension Risk. When interest rates rise, certain obligations will be paid off
  by the obligor more slowly than anticipated, causing the value of these        
  securities to fall.                                                            
  
· Foreign Investing Risk. The securities of foreign issuers may be less liquid   
  and more volatile than securities of comparable U.S. issuers. Investments in   
  securities of foreign issuers, even those publicly traded in the United States,
  may involve risks which are in addition to those inherent in domestic          
  investments. Foreign companies may not be subject to the same regulatory       
  requirements of U.S. companies, and as a consequence, there may be less        
  publicly available information about such companies. Also, foreign companies   
  may not be subject to uniform accounting, auditing, and financial reporting    
  standards and requirements comparable to those applicable to U.S. companies.   
  Foreign governments and foreign economies often are less stable than the U.S.  
  Government and the U.S. economy.                                               
  
· Interest Rate Risk. In general, the value of bonds and other debt securities   
  falls when interest rates rise. Generally, the longer the duration of a debt   
  security, the greater is the negative effect on its value when rates           
  increase. Because zero coupon debt securities do not pay interest, the market  
  value of such securities can fall more dramatically than interest-paying       
  securities of similar maturities when interest rates rise. While bonds and     
  other debt securities normally fluctuate less in price than common stocks,     
  there have been extended periods of increases in interest rates that have      
  caused significant declines in bond prices.                                    
  
· Management Risk. The 2024 (1942-1947) Fund is subject to management risk       
  because it is an actively managed portfolio. The portfolio manager's management
  practices, investment strategies, and choice of investments might not work to  
  produce the desired results and the Fund might underperform other comparable   
  funds.                                                                         
  
· Market Risk. The prices of the securities in which the 2024 (1942-1947) Fund   
  invests may decline for a number of reasons including in response to economic  
  developments and perceptions about the creditworthiness of individual          
  issuers. Longer-term bonds, in which the Fund will invest a majority of its    
  assets, are generally more volatile.                                           
  
· New Fund Risk. The 2024 (1942-1947) Fund is new with no operating history and  
  there can be no assurance that the Fund will grow to or maintain an            
  economically viable size. If the Fund does not grow to or maintain an          
  economically viable size the Board may consider various alternatives, including
  the liquidation of the Fund or the merger of the Fund into another mutual fund.

· Portfolio Duration Target Formula Risk. There is no guarantee that adherence to
  the portfolio duration target formula will result in the Fund achieving its    
  investment objective.                                                          
  
· Prepayment Risk. When interest rates fall, certain obligations will be paid off
  by the obligor more quickly than originally anticipated, and the 2024          
  (1942-1947) Fund may have to invest the proceeds in securities with lower      
  yields (this is known as Reinvestment Risk).                                   
  
· Termination Risk. Because the 2024 (1942-1947) Fund has a Termination Date and
  it will invest a majority of its assets in securities that mature after the    
  Termination Date, the Fund may incur liquidation costs to liquidate its        
  portfolio.                                                                     
  
· U.S. Government Issuer Risk. Treasury obligations may differ in their interest
  rates, maturities, times of issuance and other characteristics. Obligations of
  U.S. Government agencies and authorities are supported by varying degrees of   
  credit but generally are not backed by the full faith and credit of the U.S.   
  Government. No assurance can be given that the U.S. Government will provide    
  financial support to its agencies and authorities if it is not obligated by law
  to do so.

Performance

When the 2024 (1942-1947) Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2024 (b.1942-1947) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra Pension Reserve Fund 2016 (b. 1953-1957) (Prospectus Summary) | Symetra Pension Reserve Fund 2016 (b. 1953-1957)
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra Pension Reserve Fund - 2016 (b.1953-1957)
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra Pension Reserve Fund - 2016 (b.1953-1957) (the "2016 (1953-1957) Fund" or the "Fund") seeks investment returns that would provide an amount on the Fund's termination date approximately equal to the then present value of specified lifetime annuity payments to be made to investors born in the year range identified in the Fund's name. As a result of its investment objective, a Pension Reserve Fund may not be a wise investment choice for an investor who does not anticipate applying his or her accumulation to the purchase of a lifetime annuity on or shortly after the Fund's termination date.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the 2016 (1953-1957) Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The 2016 (1953-1957) Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" is an estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the 2016 (1953-1957) Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The 2016 (1953-1957) Fund invests primarily in government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the three highest categories by an NRSRO or unrated securities that the Sub-Adviser determines are of comparable quality. The Fund also may invest in other types of dollar-denominated investment grade debt securities, including money market instruments and securities of foreign issuers. Most of the securities held by the Fund are zero coupon debt securities. Under normal market conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the two highest categories by an NRSRO, and investing in other permitted investments when government securities and corporate securities in the two highest categories are not available in sufficient quantities at a reasonable price or are not available in optimal durations or maturities.  The Fund also may manage portfolio duration by investing in interest rate futures contracts, options on interest rate futures contracts, structured notes and entering into swap agreements, provided that structured notes and swap agreements are determined by the Sub-Adviser to pose minimal counter-party credit risk. The 2016 (1953-1957) Fund is managed to continuously meet portfolio duration targets that correspond to projected payments, based on actuarially determined survivorship rates, of a single life annuity on the life of a person born in the year-range identified in the Fund's name. The portfolio duration targets are recalculated at least monthly based on a formula established by the Adviser (after consultation with Symetra Life Insurance Company ("Symetra Life")) at the Fund's inception. The formula will not change once the Fund commences operations. (The only variables in the formula are the amount of time remaining until each annual projected payment of the single life annuity and the prevailing interest rates on the recalculation date. The prevailing interest rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet the Fund's daily portfolio duration target by first, to the extent that such investments are available, investing in securities having cash flows similar to the projected payments of the single life annuity and then by balancing investments in securities with longer and shorter durations than the target duration. The portfolio duration target generally declines for the Fund over the life of the Fund, but will be substantially greater than zero at the Fund's termination date. As a result, to meet the portfolio duration target, the Fund will likely have an investment portfolio at its termination date of debt securities of substantial remaining duration. This in turn, will result in the market value of the Fund's investment portfolio at the termination date being significantly influenced by prevailing interest rates. Generally speaking, the higher the prevailing rates at the Fund's maturity, the less the Fund will receive from selling its assets and the lower the prevailing rates, the more the Fund will receive for selling its assets. Thus, the market value of such assets is inversely related to prevailing interest rates. The present value of a future series of payments decreases as the interest rate on which the present value is computed increases. Therefore, on the 2016 (1953-1957) Fund's termination date the present value of the annuity payments the investor is entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund will be less the higher the prevailing interest rates. The Fund's adherence to the portfolio duration target formula is intended to result in the Fund having on its termination date net assets approximately equal to the present value of the aggregate annuity payments investors are entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund. However, even if a Fund successfully adheres to the formula, there is no guarantee that it will achieve this intended result or its investment objective. Although the Fund has no current plans to close, there is no guarantee that the Fund will continue to accept new investments until the termination date. As of the date of this Prospectus, based on the current U.S. Treasury Zero Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2016 (1953-1957) Fund's portfolio duration target would have been 17.2 years.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the 2016 (1953-1957) Fund. The following additional risks could affect the value of your investment: · Credit Risk. The issuers of the bonds and other debt securities held by the       2016 (1953-1957) Fund may not be able to make interest or principal payments      when due. Even if these issuers are able to make interest or principal            payments, changes in an issuer's credit rating or the market's perception of an   issuer's creditworthiness may also affect the value of the Fund's investment in   that issuer by leading to greater volatility in the price of the security.         · Credit Default Swap Risk. In a credit default swap transaction, both the 2016   (1953-1957) Fund and its counter-party are exposed to the risk of default by      the other. In addition, the terms of most credit default swap transactions        require little or no initial investment by the seller in relation to the          notional amount of the swap and the corresponding risk. Therefore, small          changes in the market value of the reference security or group of securities      may produce disproportionate and substantial losses for the seller.             · Derivatives Risk. Derivatives are securities, such as futures contracts, whose   value is derived from that of other securities or indices. The 2016 (1953-1957)   Fund's investments in derivatives may pose risks in addition to those             associated with investing directly in securities or other investments.            Derivative securities are subject to a number of risks including liquidity,       interest rate, market, credit and management risks, the risk of improper          valuation, illiquidity of the derivatives, imperfect correlations with            underlying investments or the Fund's other portfolio holdings, lack of            availability and counterparty risk. Changes in the value of the derivative may   not correlate perfectly with the underlying asset, rate or index, and the Fund   could lose more than the principal amount invested. An investment in              derivatives may not perform as anticipated by the Sub-Adviser, may not be able   to be closed out at a favorable time or price. An investment in derivatives may   also increase the Fund's volatility and create investment leverage. When a        derivative is used as a substitute or alternative to a direct cash investment,   the transaction may not provide a return that corresponds precisely with that     of the cash investment; or, when used for hedging purposes, derivatives may not   provide the anticipated protection, causing the Fund to lose money on both the   derivatives transaction and the exposure the Fund sought to hedge.              · Extension Risk. When interest rates rise, certain obligations will be paid off   by the obligor more slowly than anticipated, causing the value of these           securities to fall.                                                             · Foreign Investing Risk. The securities of foreign issuers may be less liquid      and more volatile than securities of comparable U.S. issuers. Investments in      securities of foreign issuers, even those publicly traded in the United States,   may involve risks which are in addition to those inherent in domestic             investments. Foreign companies may not be subject to the same regulatory          requirements of U.S. companies, and as a consequence, there may be less           publicly available information about such companies. Also, foreign companies      may not be subject to uniform accounting, auditing, and financial reporting       standards and requirements comparable to those applicable to U.S. companies.      Foreign governments and foreign economies often are less stable than the U.S.     Government and the U.S. economy.                                                · Interest Rate Risk. In general, the value of bonds and other debt securities      falls when interest rates rise. Generally, the longer the duration of a debt      security, the greater is the negative effect on its value when rates              increase. Because zero coupon debt securities do not pay interest, the market     value of such securities can fall more dramatically than interest-paying          securities of similar maturities when interest rates rise. While bonds and        other debt securities normally fluctuate less in price than common stocks,        there have been extended periods of increases in interest rates that have         caused significant declines in bond prices.                                     · Management Risk. The 2016 (1953-1957) Fund is subject to management risk          because it is an actively managed portfolio. The portfolio manager's management   practices, investment strategies, and choice of investments might not work to     produce the desired results and the Fund might underperform other comparable      funds.                                                                          · Market Risk. The prices of the securities in which the 2016 (1953-1957) Fund      invests may decline for a number of reasons including in response to economic     developments and perceptions about the creditworthiness of individual             issuers. Longer-term bonds, in which the Fund will invest a majority of its       assets, are generally more volatile.                                            · New Fund Risk. The 2016 (1953-1957) Fund is new with no operating history and     there can be no assurance that the Fund will grow to or maintain an               economically viable size. If the Fund does not grow to or maintain an             economically viable size the Board may consider various alternatives, including   the liquidation of the Fund or the merger of the Fund into another mutual fund.    · Portfolio Duration Target Formula Risk. There is no guarantee that adherence to   the portfolio duration target formula will result in the Fund achieving its       investment objective.                                                           · Prepayment Risk. When interest rates fall, certain obligations will be paid off   by the obligor more quickly than originally anticipated, and the 2016             (1953-1957) Fund may have to invest the proceeds in securities with lower         yields (this is known as Reinvestment Risk).                                    · Termination Risk. Because the 2016 (1953-1957) Fund has a Termination Date and   it will invest a majority of its assets in securities that mature after the       Termination Date, the Fund may incur liquidation costs to liquidate its           portfolio.                                                                      · U.S. Government Issuer Risk. Treasury obligations may differ in their interest   rates, maturities, times of issuance and other characteristics. Obligations of   U.S. Government agencies and authorities are supported by varying degrees of      credit but generally are not backed by the full faith and credit of the U.S.      Government. No assurance can be given that the U.S. Government will provide       financial support to its agencies and authorities if it is not obligated by law   to do so.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the 2016 (1953-1957) Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the 2016 (1953-1957) Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the 2016 (1953-1957) Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-SYMETRA (1-800-796-3872)
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra Pension Reserve Fund 2016 (b. 1953-1957) (Prospectus Summary) | Symetra Pension Reserve Fund 2016 (b. 1953-1957) | Symetra Pension Reserve Fund 2016 (b. 1953-1957)
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.32%
Other Expenses	rr_OtherExpensesOverAssets	1.77%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.09%
Less: Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.69%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.40%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	41
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	491

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2016 (b.1953-1957) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Symetra DoubleLine Total Return Fund (Prospectus Summary) | Symetra DoubleLine Total Return Fund

Symetra DoubleLine® Total Return Fund

Investment Objective

The Symetra DoubleLine® Total Return Fund (the "Total Return Fund" or the
"Fund") seeks total return through both income and capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the Total Return Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity or variable life insurance contract level. If
those additional fees and expenses were included, overall expenses would be
higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra DoubleLine Total Return Fund
Management Fees		0.55%
Other Expenses	[1]	2.10%
Total Annual Fund Operating Expenses		2.65%
Less: Fee Waiver and Expense Reimbursement	[2]	(2.02%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.63%

Example

This Example is intended to help you compare the cost of investing in the Total
Return Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated and
then redeem all of your shares at the end of those periods. The Example also
assumes that your investment has a 5% return each year and that the Fund's
operating expenses remain the same (taking into account the Expense Cap and Fee
Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra DoubleLine Total Return Fund	64	631

Portfolio Turnover

The Total Return Fund pays transaction costs, such as commissions, when it buys
and sells securities (or "turns over" its portfolio). A higher portfolio
turnover rate may indicate higher transaction costs and may result in higher
taxes when Fund shares are held in a taxable account. These costs, which are not
reflected in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Total Return Fund

Under normal market conditions, the Fund pursues its investment objective by
investing at least 80% of its net assets (plus the amount of borrowings for
investment purposes) in debt securities. Under normal market conditions, the
Fund invests more than half of its assets in mortgage-backed government
securities, mortgage-backed securities collateralized by government securities,
and privately-issued high grade mortgage-backed securities, including inverse
floaters. The Fund also may invest up to 35% of its assets in lower-rated bonds
(commonly known as junk bonds), bank loans and assignments, and credit default
swap agreements. Investment in secured or unsecured fixed or floating rate loans
arranged through private negotiations between a borrower and one or more
financial institutions may be in the form of participations in loans or
assignments of all or a portion of loans from third parties. Under normal market
conditions, the Fund generally seeks a target weighted average effective
duration of one to eight years, though actual duration may vary considerably
from this target.

Portfolio securities may be sold at any time. Sales may occur when the Total
Return Fund's portfolio managers determine to take advantage of a better
investment opportunity because the portfolio managers believe the portfolio
securities no longer represent relatively attractive investment opportunities,
there is perceived deterioration in the credit fundamentals of the issuer or if
they believe it would be appropriate to do so in order to readjust the duration
of the Fund's investment portfolio.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the Total
Return Fund. The following additional risks could affect the value of your
investment:

· Credit Risk. The issuers of the bonds and other debt securities held by the    
  Fund may not be able to make interest or principal payments when due. Even if  
  these issuers are able to make interest or principal payments, changes in an   
  issuer's credit rating or the market's perception of an issuer's               
  creditworthiness may also affect the value of the Fund's investment in that    
  issuer by leading to greater volatility in the price of the security.          
  
· Credit Default Swap Risk. In a credit default swap transaction, both the Fund
  and its counter-party are exposed to the risk of default by the other. In      
  addition, the terms of most credit default swap transactions require little or
  no initial investment by the seller in relation to the notional amount of the  
  swap and the corresponding risk. Therefore, small changes in the market value  
  of the reference security or group of securities may produce disproportionate  
  and substantial losses for the seller.                                         

· Defaulted Securities Risk. There is a high level of uncertainty regarding the  
  repayment of defaulted securities and obligations of distressed issuers.       

· Interest Rate Risk. In general, the value of bonds and other debt securities   
  falls when interest rates rise. Generally, the longer the duration of a debt   
  security, the greater is the negative effect on its value when rates           
  increase. While bonds and other debt securities normally fluctuate less in     
  price than common stocks, there have been extended periods of increases in     
  interest rates that have caused significant declines in bond prices.           

· Junk Bond Risk. Although junk bonds generally pay higher rates of interest than
  investment grade bonds, junk bonds are high risk investments that may cause    
  income and principal losses for the Total Return Fund. Junk bonds are subject  
  to reduced creditworthiness of issuers; increased risk of default and a more   
  limited and less liquid secondary market than higher rated securities; and     
  greater price volatility and risk of loss of income and principal than are     
  higher rated securities.                                                       

· Leveraging Risk. Certain investments by the Total Return Fund may involve      
  leverage, which may have the effect of increasing the volatility of the Fund's
  portfolio, and the risk of loss in excess of invested capital.                 
                                         
· Liquidity Risk. In certain circumstances, low trading volume, lack of a market
  maker, or contractual or legal restrictions may limit or prevent the Total     
  Return Fund from selling securities or closing any derivative positions within
  a reasonable time at desirable prices. In addition, the ability of the Fund to
  assign an accurate daily value to certain investments may be difficult, and the
  Adviser may be required to fair value the investments.                         

· Management Risk. The Total Return Fund is subject to management risk because it
  is an actively managed portfolio. The portfolio managers' management practices,
  investment strategies, and choice of investments might not work to produce the
  desired results and the Fund might underperform other comparable funds.        
  
· Market Risk. The prices of the securities in which the Total Return Fund       
  invests may decline for a number of reasons including in response to economic  
  or political developments and perceptions about the creditworthiness of        
  individual issuers or other issuer-specific events.                            
  
· Mortgage-backed Securities Risk. Borrowers may default on their mortgage       
  obligations or the guarantees underlying the mortgage-backed securities may    
  default or otherwise fail and, during periods of falling interest rates,       
  mortgage-backed securities may be paid off by the obligor more quickly than    
  originally anticipated (this is known as Prepayment Risk), which may result in
  the Total Return Fund having to reinvest proceeds in other investments at a    
  lower interest rate (this is also known as Reinvestment Risk). During periods  
  of rising interest rates, the average life of a mortgage-backed security may   
  extend, which may lock in a below-market interest rate, increase the security's
  duration, and reduce the value of the security. Enforcing rights against the   
  underlying assets or collateral may be difficult, or the underlying assets or  
  collateral may be insufficient if the issuer defaults. The values of certain   
  types of mortgage-backed securities, such as inverse floaters and interest-only
  and principal-only securities, may be extremely sensitive to changes in        
  interest rates and prepayment rates.                                           
  
· New Fund Risk. The Total Return Fund is new with no operating history and there
  can be no assurance that the Fund will grow to or maintain an economically     
  viable size. If the Fund does not grow to or maintain an economically viable   
  size, the Board may consider various alternatives, including the liquidation of
  the Fund or the merger of the Fund into another mutual fund.                   

· Real Estate Risk. Real estate-related investments may decline in value as a    
  result of factors affecting the real estate industry, such as the supply of    
  real property in certain markets, changes in zoning laws, delays in completion
  of construction, changes in real estate values, changes in property taxes,     
  levels of occupancy, and local and regional market conditions.                 
  
· U.S. Government Issuer Risk. Treasury obligations may differ in their interest
  rates, maturities, times of issuance and other characteristics. Obligations of
  U.S. Government agencies and authorities are supported by varying degrees of   
  credit but generally are not backed by the full faith and credit of the U.S.   
  Government. No assurance can be given that the U.S. Government will provide    
  financial support to its agencies and authorities if it is not obligated by law
  to do so.

Performance

When the Total Return Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Total Return Fund (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra Pension Reserve Fund 2024 (b. 1948-1952) (Prospectus Summary) | Symetra Pension Reserve Fund 2024 (b. 1948-1952)
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra Pension Reserve Fund - 2024 (b.1948-1952)
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra Pension Reserve Fund - 2024 (b.1948-1952) (the "2024 (1948-1952) Fund" or the "Fund") seeks investment returns that would provide an amount on the Fund's termination date approximately equal to the then present value of specified lifetime annuity payments to be made to investors born in the year range identified in the Fund's name. As a result of its investment objective, a Pension Reserve Fund may not be a wise investment choice for an investor who does not anticipate applying his or her accumulation to the purchase of a lifetime annuity on or shortly after the Fund's termination date.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the 2024 (1948-1952) Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The 2024 (1948-1952) Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" is an estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the 2024 (1948-1952) Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The 2024 (1948-1952) Fund invests primarily in government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the three highest categories by an NRSRO or unrated securities that the Sub-Adviser determines are of comparable quality. The Fund also may invest in other types of dollar-denominated investment grade debt securities, including money market instruments and securities of foreign issuers. Most of the securities held by the Fund are zero coupon debt securities. Under normal market conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the two highest categories by an NRSRO, and investing in other permitted investments when government securities and corporate securities in the two highest categories are not available in sufficient quantities at a reasonable price or are not available in optimal durations or maturities.  The Fund also may manage portfolio duration by investing in interest rate futures contracts, options on interest rate futures contracts, structured notes and entering into swap agreements, provided that structured notes and swap agreements are determined by the Sub-Adviser to pose minimal counter-party credit risk. The 2024 (1948-1952) Fund is managed to continuously meet portfolio duration targets that correspond to projected payments, based on actuarially determined survivorship rates, of a single life annuity on the life of a person born in the year-range identified in the Fund's name. The portfolio duration targets are recalculated at least monthly based on a formula established by the Adviser (after consultation with Symetra Life Insurance Company ("Symetra Life")) at the Fund's inception. The formula will not change once the Fund commences operations. (The only variables in the formula are the amount of time remaining until each annual projected payment of the single life annuity and the prevailing interest rates on the recalculation date. The prevailing interest rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet the Fund's daily portfolio duration target by first, to the extent that such investments are available, investing in securities having cash flows similar to the projected payments of the single life annuity and then by balancing investments in securities with longer and shorter durations than the target duration. The portfolio duration target generally declines for the Fund over the life of the Fund, but will be substantially greater than zero at the Fund's termination date. As a result, to meet the portfolio duration target, the Fund will likely have an investment portfolio at its termination date of debt securities of substantial remaining duration. This in turn, will result in the market value of the Fund's investment portfolio at the termination date being significantly influenced by prevailing interest rates. Generally speaking, the higher the prevailing rates at the Fund's maturity, the less the Fund will receive from selling its assets and the lower the prevailing rates, the more the Fund will receive for selling its assets. Thus, the market value of such assets is inversely related to prevailing interest rates. The present value of a future series of payments decreases as the interest rate on which the present value is computed increases. Therefore, on the 2024 (1948-1952) Fund's termination date the present value of the annuity payments the investor is entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund will be less the higher the prevailing interest rates. The Fund's adherence to the portfolio duration target formula is intended to result in the Fund having on its termination date net assets approximately equal to the present value of the aggregate annuity payments investors are entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund. However, even if a Fund successfully adheres to the formula, there is no guarantee that it will achieve this intended result or its investment objective. Although the Fund has no current plans to close, there is no guarantee that the Fund will continue to accept new investments until the termination date. As of the date of this Prospectus, based on the current U.S. Treasury Zero Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2024 (1948-1952) Fund's portfolio duration target would have been 20.1 years.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the 2024 (1948-1952) Fund. The following additional risks could affect the value of your investment: · Credit Risk. The issuers of the bonds and other debt securities held by the       2024 (1948-1952) Fund may not be able to make interest or principal payments      when due. Even if these issuers are able to make interest or principal            payments, changes in an issuer's credit rating or the market's perception of an   issuer's creditworthiness may also affect the value of the Fund's investment in   that issuer by leading to greater volatility in the price of the security.      · Credit Default Swap Risk. In a credit default swap transaction, both the 2024   (1948-1952) Fund and its counter-party are exposed to the risk of default by      the other. In addition, the terms of most credit default swap transactions        require little or no initial investment by the seller in relation to the          notional amount of the swap and the corresponding risk. Therefore, small          changes in the market value of the reference security or group of securities      may produce disproportionate and substantial losses for the seller.             · Derivatives Risk. Derivatives are securities, such as futures contracts, whose   value is derived from that of other securities or indices. The Fund's             investments in derivatives may pose risks in addition to those associated with   investing directly in securities or other investments. Derivative securities      are subject to a number of risks including liquidity, interest rate, market,      credit and management risks, the risk of improper valuation, illiquidity of the   derivatives, imperfect correlations with underlying investments or the Fund's     other portfolio holdings, lack of availability and counterparty risk. Changes     in the value of the derivative may not correlate perfectly with the underlying   asset, rate or index, and the Fund could lose more than the principal amount      invested. An investment in derivatives may not perform as anticipated by the      Sub-Adviser, may not be able to be closed out at a favorable time or price. An   investment in derivatives may also increase the Fund's volatility and create      investment leverage. When a derivative is used as a substitute or alternative     to a direct cash investment, the transaction may not provide a return that        corresponds precisely with that of the cash investment; or, when used for         hedging purposes, derivatives may not provide the anticipated protection,         causing the Fund to lose money on both the derivatives transaction and the        exposure the Fund sought to hedge.                                                 · Extension Risk. When interest rates rise, certain obligations will be paid off   by the obligor more slowly than anticipated, causing the value of these           securities to fall.                                                                · Foreign Investing Risk. The securities of foreign issuers may be less liquid      and more volatile than securities of comparable U.S. issuers. Investments in      securities of foreign issuers, even those publicly traded in the United States,   may involve risks which are in addition to those inherent in domestic             investments. Foreign companies may not be subject to the same regulatory          requirements of U.S. companies, and as a consequence, there may be less           publicly available information about such companies. Also, foreign companies      may not be subject to uniform accounting, auditing, and financial reporting       standards and requirements comparable to those applicable to U.S. companies.      Foreign governments and foreign economies often are less stable than the U.S.     Government and the U.S. economy.                                                   · Interest Rate Risk. In general, the value of bonds and other debt securities      falls when interest rates rise. Generally, the longer the duration of a debt      security, the greater is the negative effect on its value when rates              increase. Because zero coupon debt securities do not pay interest, the market     value of such securities can fall more dramatically than interest-paying          securities of similar maturities when interest rates rise. While bonds and        other debt securities normally fluctuate less in price than common stocks,        there have been extended periods of increases in interest rates that have         caused significant declines in bond prices.                                     · Management Risk. The 2024 (1948-1952) Fund is subject to management risk          because it is an actively managed portfolio. The portfolio manager's management   practices, investment strategies, and choice of investments might not work to     produce the desired results and the Fund might underperform other comparable      funds.                                                                          · Market Risk. The prices of the securities in which the 2024 (1948-1952) Fund      invests may decline for a number of reasons including in response to economic     developments and perceptions about the creditworthiness of individual             issuers. Longer-term bonds, in which the Fund will invest a majority of its       assets, are generally more volatile.                                            · New Fund Risk. The 2024 (1948-1952) Fund is new with no operating history and     there can be no assurance that the Fund will grow to or maintain an               economically viable size. If the Fund does not grow to maintain an economically   viable size the Board may consider various alternatives, including the            liquidation of the Fund or the merger of the Fund into another mutual fund.     · Portfolio Duration Target Formula Risk. There is no guarantee that adherence to   the portfolio duration target formula will result in the Fund achieving its       investment objective.                                                              · Prepayment Risk. When interest rates fall, certain obligations will be paid off   by the obligor more quickly than originally anticipated, and the Fund may have   to invest the proceeds in securities with lower yields (this is known as          Reinvestment Risk).                                                                · Termination Risk. Because the 2024 (1948-1952) Fund has a Termination Date and   it will invest a majority of its assets in securities that mature after the       Termination Date, the Fund may incur liquidation costs to liquidate its           portfolio.                                                                      · U.S. Government Issuer Risk. Treasury obligations may differ in their interest   rates, maturities, times of issuance and other characteristics. Obligations of   U.S. Government agencies and authorities are supported by varying degrees of      credit but generally are not backed by the full faith and credit of the U.S.      Government. No assurance can be given that the U.S. Government will provide       financial support to its agencies and authorities if it is not obligated by law   to do so.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the 2024 (1948-1952) Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the 2024 (1948-1952) Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the 2024 (1948-1952) Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-SYMETRA (1-800-796-3872)
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra Pension Reserve Fund 2024 (b. 1948-1952) (Prospectus Summary) | Symetra Pension Reserve Fund 2024 (b. 1948-1952) | Symetra Pension Reserve Fund 2024 (b. 1948-1952)
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.32%
Other Expenses	rr_OtherExpensesOverAssets	1.77%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.09%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.69%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.40%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	41
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	491

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements,acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2024 (b.1948-1952) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Symetra DoubleLine Emerging Markets Income Fund (Prospectus Summary) | Symetra DoubleLine Emerging Markets Income Fund

Symetra DoubleLine Emerging Markets Income Fund

Investment Objective

The Symetra DoubleLine Emerging Markets Income Fund (the "Emerging Markets Fund"
or the "Fund") seeks total return through both income and capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the Emerging Markets Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity or variable life insurance contract level. If
those additional fees and expenses were included, overall expenses would be
higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra DoubleLine Emerging Markets Income Fund
Management Fees		0.90%
Other Expenses	[1]	1.48%
Total Annual Fund Operating Expenses		2.38%
Less: Fee Waiver and Expense Reimbursement	[2]	(1.40%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.98%

Example

This Example is intended to help you compare the cost of investing in the
Emerging Markets Fund with the cost of investing in other mutual funds. The
Example assumes that you invest $10,000 in the Fund for the time periods
indicated and then redeem all of your shares at the end of those periods. The
Example also assumes that your investment has a 5% return each year and that the
Fund's operating expenses remain the same (taking into account the Expense Cap
and Fee Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra DoubleLine Emerging Markets Income Fund	100	608

Portfolio Turnover

The Emerging Markets Fund pays transaction costs, such as commissions, when it
buys and sells securities (or "turns over" its portfolio). A higher portfolio
turnover rate may indicate higher transaction costs and may result in higher
taxes when Fund shares are held in a taxable account. These costs, which are not
reflected in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Fund

Under normal market conditions the Emerging Markets Fund pursues its investment
objective by investing at least 80% of its net assets (plus the amount of
borrowings for investment purposes) in debt securities of foreign issuers that
are located in emerging market countries or whose securities are traded in
emerging markets. The Fund generally maintains investments in securities of
issuers in at least four emerging market countries. Nonetheless, the Fund is not
a diversified mutual fund under the 1940 Act. In allocating investments among
various emerging market countries, the Fund's Sub-Adviser attempts to analyze
various internal economic, market and political factors, including the
following: (1) public finance, (2) monetary policy, (3) external accounts, (4)
financial markets, (5) regulation of foreign investments, (6) exchange rate
policy, and (7) labor conditions.

An emerging market country is a country that, at the time the Emerging Markets
Fund invests in the related debt instruments, is classified as an emerging or
developing economy by any supranational organization such as the World Bank or
the United Nations, or related entities, or is considered an emerging market
country for purposes of constructing major emerging market securities indexes.

The Emerging Markets Fund may invest without limitation in lower-rated
securities, commonly known as junk bonds, and may invest up to 20% of its assets
in defaulted corporate securities when the Sub-Adviser believes that the
restructured enterprise valuation or liquidation valuation may significantly
exceed current market valuations. In addition, the Fund may invest in defaulted
foreign government debt securities where the Sub-Adviser believes that the
expected debt sustainability of the country exceeds current market
valuations. In order to hedge the Fund's portfolio, as well as for investment
purposes, the Fund may purchase or sell options on securities in which it may
invest and invest in interest rate futures contracts, options on interest rate
futures contracts, structured notes, foreign currency futures contracts, foreign
currency forward contracts and enter into swap agreements (including credit
default swaps).

Under normal market conditions, the Emerging Markets Fund generally seeks a
target weighted average effective duration of two to eight years, though actual
duration may vary considerably from this target.

Portfolio securities may be sold at any time. Sales may occur when the Emerging
Markets Fund's portfolio manager perceives deterioration in the credit
fundamentals of the issuer, the portfolio manager believes there are negative
macro geo-political considerations that may affect the issuer, the portfolio
manager determines to take advantage of a better investment opportunity or the
individual security has reached the portfolio manager's sell target.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the
Emerging Markets Fund. The following additional risks could affect the value of
your investment:

· Active Trading Risk. Active trading, also called "high portfolio turnover," may
  result in higher brokerage costs or mark-up charges, as compared to a fund that
  trades less frequently, which may negatively affect Fund performance.          
  
· Credit Risk. The issuers of the bonds and other debt securities held by the    
  Emerging Markets Fund may not be able to make interest or principal payments   
  when due. Even if these issuers are able to make interest or principal         
  payments, changes in an issuer's credit rating or the market's perception of an
  issuer's creditworthiness may also affect the value of the Fund's investment in
  that issuer by leading to greater volatility in the price of the security.     
  
· Defaulted Securities Risk. There is a high level of uncertainty regarding the  
  repayment of defaulted securities and obligations of distressed issuers.       

· Derivatives Risk.  Derivatives are securities, such as futures contracts, whose
  values are derived from those of other securities or indices. The Emerging     
  Markets Fund's investments in derivatives may pose risks in addition to those  
  associated with investing directly in securities or other investments.         
  Derivative securities are subject to a number of risks including liquidity,    
  interest rate, market, credit and management risks, the risk of improper       
  valuation, illiquidity of the derivatives, imperfect correlations with         
  underlying investments or the Fund's other portfolio holdings, lack of         
  availability and counterparty risk. Changes in the value of the derivative may
  not correlate perfectly with the underlying asset, rate or index, and the Fund
  could lose more than the principal amount invested. An investment in           
  derivatives may not perform as anticipated by the Sub-Adviser, may not be able
  to be closed out at a favorable time or price. An investment in derivatives may
  also increase the Fund's volatility and create investment leverage. When a     
  derivative is used as a substitute or alternative to a direct cash investment,
  the transaction may not provide a return that corresponds precisely with that  
  of the cash investment; or, when used for hedging purposes, derivatives may not
  provide the anticipated protection, causing the Fund to lose money on both the
  derivatives transaction and the exposure the Fund sought to hedge.             

· Foreign Investing Risk. The securities of foreign issuers may be less liquid   
  and more volatile than securities of comparable U.S. issuers. The costs        
  associated with securities transactions are often higher in foreign countries  
  than the U.S. The U.S. dollar value of securities of foreign issuers traded in
  foreign currencies (and any dividends and interest earned) held by the Emerging
  Markets Fund may be affected favorably or unfavorably by changes in foreign    
  currency exchange rates. An increase in the U.S. dollar relative to these other
  currencies will adversely affect the Fund (this is known as Foreign Currency   
  Risk). The Fund does not hedge foreign currency risk. Additionally, investments
  in securities of foreign issuers, even those publicly traded in the United     
  States, may involve risks which are in addition to those inherent in domestic  
  investments. Foreign companies may not be subject to the same regulatory       
  requirements of U.S. companies, and as a consequence, there may be less        
  publicly available information about such companies. Also, foreign companies   
  may not be subject to uniform accounting, auditing, and financial reporting    
  standards and requirements comparable to those applicable to U.S. companies.   
  Foreign governments and foreign economies often are less stable than the U.S.  
  Government and the U.S. economy. These risks are magnified for emerging markets
  countries (Emerging Market Country Risk) due to the greater degree of economic,
  political and social instability of emerging market countries as compared to   
  developed countries.                                                           

· Interest Rate Risk. In general, the value of bonds and other debt securities   
  falls when interest rates rise. Generally, the longer the duration of a debt   
  security, the greater is the negative effect on its value when rates           
  increase. While bonds and other debt securities normally fluctuate less in     
  price than common stocks, there have been extended periods of increases in     
  interest rates that have caused significant declines in bond prices.           
  
· Junk Bond Risk. Although junk bonds generally pay higher rates of interest than
  investment grade bonds, junk bonds are high risk investments that may cause    
  income and principal losses for the Emerging Markets Fund. Junk bonds are      
  subject to reduced creditworthiness of issuers; increased risk of default and a
  more limited and less liquid secondary market than higher rated securities; and
  greater price volatility and risk of loss of income and principal than are     
  higher rated securities.                                                       
  
· Leveraging Risk. Certain investments by the Emerging Markets Fund may involve  
  leverage, which may have the effect of increasing the volatility of the Fund's
  portfolio, and the risk of loss in excess of invested capital.                 
  
· Liquidity Risk. In certain circumstances, low trading volume, lack of a market
  maker, or contractual or legal restrictions may limit or prevent the Emerging  
  Markets Fund from selling securities or closing any derivative positions within
  a reasonable time at desirable prices. In addition, the ability of the Fund to
  assign an accurate daily value to certain investments may be difficult, and the
  Adviser may be required to fair value the investments.                         
  
· Management Risk. The Emerging Markets Fund is subject to management risk       
  because it is an actively managed portfolio. The portfolio manager's management
  practices, investment strategies, and choice of investments might not work to  
  produce the desired results and the Fund might underperform other comparable   
  funds.                                                                         
  
· Market Risk. The prices of the securities in which the Emerging Markets Fund   
  invests may decline for a number of reasons including in response to economic  
  or political developments and perceptions about the creditworthiness of        
  individual issuers or other issuer-specific events.                            
  
· New Fund Risk. The Emerging Markets Fund is new with no operating history and  
  there can be no assurance that the Fund will grow to or maintain an            
  economically viable size. If the Fund does not grow to or maintain an          
  economically viable size, the Board may consider various alternatives,         
  including the liquidation of the Fund or the merger of the Fund into another   
  mutual fund.
                                                                  
· Non-diversification Risk. The Emerging Markets Fund is a non-diversified       
  investment company. As such, it will likely invest in fewer securities than    
  diversified investment companies and its performance may be more volatile. The
  Fund may be more susceptible to any single economic, political or regulatory   
  event than a more diversified fund. If the securities in which the Fund invests
  perform poorly, the Fund could incur greater losses than it would have had it  
  invested in a greater number of securities.

Performance

When the Emerging Markets Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Emerging Markets Income Fund (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra Pension Reserve Fund 2028 (b. 1953-1957) (Prospectus Summary) | Symetra Pension Reserve Fund 2028 (b. 1953-1957)
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra Pension Reserve Fund - 2028 (b.1953-1957)
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra Pension Reserve Fund - 2028 (b.1953-1957) (the "2028 (1953-1957) Fund" or the "Fund") seeks investment returns that would provide an amount on the Fund's termination date approximately equal to the then present value of specified lifetime annuity payments to be made to investors born in the year range identified in the Fund's name. As a result of its investment objective, a Pension Reserve Fund may not be a wise investment choice for an investor who does not anticipate applying his or her accumulation to the purchase of a lifetime annuity on or shortly after the Fund's termination date.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the 2028 (1953-1957) Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The 2028 (1953-1957) Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" is an estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the 2028 (1953-1957) Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The 2028 (1953-1957) Fund invests primarily in government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the three highest categories by an NRSRO or unrated securities that the Sub-Adviser determines are of comparable quality. The Fund also may invest in other types of dollar-denominated investment grade debt securities, including money market instruments and securities of foreign issuers. Most of the securities held by the Fund are zero coupon debt securities. Under normal market conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the two highest categories by an NRSRO, and investing in other permitted investments when government securities and corporate securities in the two highest categories are not available in sufficient quantities at a reasonable price or are not available in optimal durations or maturities.  The Fund also may manage portfolio duration by investing in interest rate futures contracts, options on interest rate futures contracts, structured notes and entering into swap agreements, provided that structured notes and swap agreements are determined by the Sub-Adviser to pose minimal counter-party credit risk. The 2028 (1953-1957) Fund is managed to continuously meet portfolio duration targets that correspond to projected payments, based on actuarially determined survivorship rates, of a single life annuity on the life of a person born in the year-range identified in the Fund's name. The portfolio duration targets are recalculated at least monthly based on a formula established by the Adviser (after consultation with Symetra Life Insurance Company ("Symetra Life")) at the Fund's inception. The formula will not change once the Fund commences operations. (The only variables in the formula are the amount of time remaining until each annual projected payment of the single life annuity and the prevailing interest rates on the recalculation date. The prevailing interest rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet the Fund's daily portfolio duration target by first, to the extent that such investments are available, investing in securities having cash flows similar to the projected payments of the single life annuity and then by balancing investments in securities with longer and shorter durations than the target duration. The portfolio duration target generally declines for the Fund over the life of the Fund, but will be substantially greater than zero at the Fund's termination date. As a result, to meet the portfolio duration target, the Fund will likely have an investment portfolio at its termination date of debt securities of substantial remaining duration. This in turn, will result in the market value of the Fund's investment portfolio at the termination date being significantly influenced by prevailing interest rates. Generally speaking, the higher the prevailing rates at the Fund's maturity, the less the Fund will receive from selling its assets and the lower the prevailing rates, the more the Fund will receive for selling its assets. Thus, the market value of such assets is inversely related to prevailing interest rates. The present value of a future series of payments decreases as the interest rate on which the present value is computed increases. Therefore, on the 2028 (1953-1957) Fund's termination date the present value of the annuity payments the investor is entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund will be less the higher the prevailing interest rates. The Fund's adherence to the portfolio duration target formula is intended to result in the Fund having on its termination date net assets approximately equal to the present value of the aggregate annuity payments investors are entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund. However, even if a Fund successfully adheres to the formula, there is no guarantee that it will achieve this intended result or its investment objective. Although the Fund has no current plans to close, there is no guarantee that the Fund will continue to accept new investments until the termination date. As of the date of this Prospectus, based on the current U.S. Treasury Zero Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2028 (1953-1957) Fund's portfolio duration target would have been 23.9 years.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the 2028 (1953-1957) Fund. The following additional risks could affect the value of your investment: · Credit Risk. The issuers of the bonds and other debt securities held by the       2028 (1953-1957) Fund may not be able to make interest or principal payments      when due. Even if these issuers are able to make interest or principal            payments, changes in an issuer's credit rating or the market's perception of an   issuer's creditworthiness may also affect the value of the Fund's investment in   that issuer by leading to greater volatility in the price of the security.         · Credit Default Swap Risk. In a credit default swap transaction, both the 2028   (1953-1957) Fund and its counter-party are exposed to the risk of default by      the other. In addition, the terms of most credit default swap transactions        require little or no initial investment by the seller in relation to the          notional amount of the swap and the corresponding risk. Therefore, small          changes in the market value of the reference security or group of securities      may produce disproportionate and substantial losses for the seller.             · Derivatives Risk. Derivatives are securities, such as futures contracts, whose   value is derived from that of other securities or indices. The 2028 (1953-1957)   Fund's investments in derivatives may pose risks in addition to those             associated with investing directly in securities or other investments.            Derivative securities are subject to a number of risks including liquidity,       interest rate, market, credit and management risks, the risk of improper          valuation, illiquidity of the derivatives, imperfect correlations with            underlying investments or the Fund's other portfolio holdings, lack of            availability and counterparty risk. Changes in the value of the derivative may   not correlate perfectly with the underlying asset, rate or index, and the Fund   could lose more than the principal amount invested. An investment in              derivatives may not perform as anticipated by the Sub-Adviser, may not be able   to be closed out at a favorable time or price. An investment in derivatives may   also increase the Fund's volatility and create investment leverage. When a        derivative is used as a substitute or alternative to a direct cash investment,   the transaction may not provide a return that corresponds precisely with that     of the cash investment; or, when used for hedging purposes, derivatives may not   provide the anticipated protection, causing the Fund to lose money on both the   derivatives transaction and the exposure the Fund sought to hedge.              · Extension Risk. When interest rates rise, certain obligations will be paid off   by the obligor more slowly than anticipated, causing the value of these           securities to fall.                                                             · Foreign Investing Risk. The securities of foreign issuers may be less liquid      and more volatile than securities of comparable U.S. issuers. Investments in      securities of foreign issuers, even those publicly traded in the United States,   may involve risks which are in addition to those inherent in domestic             investments. Foreign companies may not be subject to the same regulatory          requirements of U.S. companies, and as a consequence, there may be less           publicly available information about such companies. Also, foreign companies      may not be subject to uniform accounting, auditing, and financial reporting       standards and requirements comparable to those applicable to U.S. companies.      Foreign governments and foreign economies often are less stable than the U.S.     Government and the U.S. economy.                                                · Interest Rate Risk. In general, the value of bonds and other debt securities      falls when interest rates rise. Generally, the longer the duration of a debt      security, the greater is the negative effect on its value when rates              increase. Because zero coupon debt securities do not pay interest, the market     value of such securities can fall more dramatically than interest-paying          securities of similar maturities when interest rates rise. While bonds and        other debt securities normally fluctuate less in price than common stocks,        there have been extended periods of increases in interest rates that have         caused significant declines in bond prices.                                     · Management Risk. The 2028 (1953-1957) Fund is subject to management risk          because it is an actively managed portfolio. The portfolio manager's management   practices, investment strategies, and choice of investments might not work to     produce the desired results and the Fund might underperform other comparable      funds.                                                                          · Market Risk. The prices of the securities in which the 2028 (1953-1957) Fund      invests may decline for a number of reasons including in response to economic     developments and perceptions about the creditworthiness of individual             issuers. Longer-term bonds, in which the Fund will invest a majority of its       assets, are generally more volatile.                                            · New Fund Risk. The 2028 (1953-1957) Fund is new with no operating history and     there can be no assurance that the Fund will grow to or maintain an               economically viable size. If the Fund does not grow to or maintain an             economically viable size the Board may consider various alternatives, including   the liquidation of the Fund or the merger of the Fund into another mutual fund.    · Portfolio Duration Target Formula Risk. There is no guarantee that adherence to   the portfolio duration target formula will result in the Fund achieving its       investment objective.                                                           · Prepayment Risk. When interest rates fall, certain obligations will be paid off   by the obligor more quickly than originally anticipated, and the 2028             (1953-1957) Fund may have to invest the proceeds in securities with lower         yields (this is known as Reinvestment Risk).                                    · Termination Risk. Because the 2028 (1953-1957) Fund has a Termination Date and   it will invest a majority of its assets in securities that mature after the       Termination Date, the Fund may incur liquidation costs to liquidate its           portfolio.                                                                      · U.S. Government Issuer Risk. Treasury obligations may differ in their interest   rates, maturities, times of issuance and other characteristics. Obligations of   U.S. Government agencies and authorities are supported by varying degrees of      credit but generally are not backed by the full faith and credit of the U.S.      Government. No assurance can be given that the U.S. Government will provide       financial support to its agencies and authorities if it is not obligated by law   to do so.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the 2028 (1953-1957) Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the 2028 (1953-1957) Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the 2028 (1953-1957) Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-SYMETRA (1-800-796-3872)
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra Pension Reserve Fund 2028 (b. 1953-1957) (Prospectus Summary) | Symetra Pension Reserve Fund 2028 (b. 1953-1957) | Symetra Pension Reserve Fund 2028 (b. 1953-1957)
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.32%
Other Expenses	rr_OtherExpensesOverAssets	1.77%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.09%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.69%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.40%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	41
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	491

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2028 (b.1953-1957) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Symetra Pension Reserve Fund 2016 (b. 1942-1947) (Prospectus Summary) | Symetra Pension Reserve Fund 2016 (b. 1942-1947)

Symetra Pension Reserve Fund - 2016 (b.1942-1947)

Investment Objective

The Symetra Pension Reserve Fund - 2016 (b.1942-1947) (the "2016 (1942-1947)
Fund" or the "Fund") seeks investment returns that would provide an amount on
the Fund's termination date approximately equal to the then present value of
specified lifetime annuity payments to be made to investors born in the year
range identified in the Fund's name. As a result of its investment objective, a
Pension Reserve Fund may not be a wise investment choice for an investor who
does not anticipate applying his or her accumulation to the purchase of a
lifetime annuity on or shortly after the Fund's termination date.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the 2016 (1942-1947) Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity or variable life insurance contract level. If
those additional fees and expenses were included, overall expenses would be
higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra Pension Reserve Fund 2016 (b. 1942-1947)
Management Fees		0.32%
Other Expenses	[1]	1.77%
Total Annual Fund Operating Expenses		2.09%
Less: Fee Waiver and Expense Reimbursement	[2]	(1.69%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.40%

Example

This Example is intended to help you compare the cost of investing in the 2016
(1942-1947) Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated and
then redeem all of your shares at the end of those periods. The Example also
assumes that your investment has a 5% return each year and that the Fund's
operating expenses remain the same (taking into account the Expense Cap and Fee
Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra Pension Reserve Fund 2016 (b. 1942-1947)	41	491

Portfolio Turnover

The 2016 (1942-1947) Fund pays transaction costs, such as commissions, when it
buys and sells securities (or "turns over" its portfolio). A higher portfolio
turnover rate may indicate higher transaction costs and may result in higher
taxes when Fund shares are held in a taxable account. These costs, which are not
reflected in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Fund

The 2016 (1942-1947) Fund invests primarily in government securities and
dollar-denominated corporate debt securities rated, at the time of purchase, in
the three highest categories by an NRSRO or unrated securities that the
Sub-Adviser determines are of comparable quality. The Fund also may invest in
other types of dollar-denominated investment grade debt securities, including
money market instruments and securities of foreign issuers. Most of the
securities held by the Fund are zero coupon debt securities. Under normal market
conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring
government securities and dollar-denominated corporate debt securities rated, at
the time of purchase, in the two highest categories by an NRSRO, and investing
in other permitted investments when government securities and corporate
securities in the two highest categories are not available in sufficient
quantities at a reasonable price or are not available in optimal durations or
maturities.  The Fund also may manage portfolio duration by investing in
interest rate futures contracts, options on interest rate futures contracts,
structured notes and entering into swap agreements, provided that structured
notes and swap agreements are determined by the Sub-Adviser to pose minimal
counter-party credit risk.

The 2016 (1942-1947) Fund is managed to continuously meet portfolio duration
targets that correspond to projected payments, based on actuarially determined
survivorship rates, of a single life annuity on the life of a person born in the
year-range identified in the Fund's name. The portfolio duration targets are
recalculated at least monthly based on a formula established by the Adviser
(after consultation with Symetra Life Insurance Company ("Symetra Life")) at the
Fund's inception. The formula will not change once the Fund commences
operations. (The only variables in the formula are the amount of time remaining
until each annual projected payment of the single life annuity and the
prevailing interest rates on the recalculation date. The prevailing interest
rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by
interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet
the Fund's daily portfolio duration target by first, to the extent that such
investments are available, investing in securities having cash flows similar to
the projected payments of the single life annuity and then by balancing
investments in securities with longer and shorter durations than the target
duration. The portfolio duration target generally declines for the Fund over the
life of the Fund, but will be substantially greater than zero at the Fund's
termination date. As a result, to meet the portfolio duration target, the Fund
will likely have an investment portfolio at its termination date of debt
securities of substantial remaining duration. This in turn, will result in the
market value of the Fund's investment portfolio at the termination date being
significantly influenced by prevailing interest rates. Generally speaking, the
higher the prevailing rates at the Fund's maturity, the less the Fund will
receive from selling its assets and the lower the prevailing rates, the more the
Fund will receive for selling its assets. Thus, the market value of such assets
is inversely related to prevailing interest rates.

The present value of a future series of payments decreases as the interest rate
on which the present value is computed increases. Therefore, on the 2016
(1942-1947) Fund's termination date the present value of the annuity payments
the investor is entitled to receive as a result of owning accumulation units in
the sub-account of the Symetra Resource Variable Account B that invests in
shares of the Fund will be less the higher the prevailing interest rates. The
Fund's adherence to the portfolio duration target formula is intended to result
in the Fund having on its termination date net assets approximately equal to the
present value of the aggregate annuity payments investors are entitled to
receive as a result of owning accumulation units in the sub-account of the
Symetra Resource Variable Account B that invests in shares of the Fund. However,
even if a Fund successfully adheres to the formula, there is no guarantee that
it will achieve this intended result or its investment objective. Although the
Fund has no current plans to close, there is no guarantee that the Fund will
continue to accept new investments until the termination date.

As of the date of this Prospectus, based on the current U.S. Treasury Zero
Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2016
(1942-1947) Fund's portfolio duration target would have been 13.8 years.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the 2016
(1942-1947) Fund. The following additional risks could affect the value of your
investment:

· Credit Risk. The issuers of the bonds and other debt securities held by the  
  2016 (1942-1947) Fund may not be able to make interest or principal payments
  when due. Even if these issuers are able to make interest or principal       
  payments, changes in an issuer's credit rating or the market's perception of
  an issuer's creditworthiness may also affect the value of the Fund's         
  investment in that issuer by leading to greater volatility in the price of   
  the security.                                                                

· Credit Default Swap Risk. In a credit default swap transaction, both the 2016
  (1942-1947) Fund and its counter-party are exposed to the risk of default by   
  the other. In addition, the terms of most credit default swap transactions     
  require little or no initial investment by the seller in relation to the       
  notional amount of the swap and the corresponding risk. Therefore, small       
  changes in the market value of the reference security or group of securities   
  may produce disproportionate and substantial losses for the seller.            
  
· Derivatives Risk. Derivatives are securities, such as futures contracts, whose
  value is derived from that of other securities or indices. The 2016 (1942-1947)
  Fund's investments in derivatives may pose risks in addition to those          
  associated with investing directly in securities or other investments.         
  Derivative securities are subject to a number of risks including liquidity,    
  interest rate, market, credit and management risks, the risk of improper       
  valuation, illiquidity of the derivatives, imperfect correlations with         
  underlying investments or the Fund's other portfolio holdings, lack of         
  availability and counterparty risk. Changes in the value of the derivative may
  not correlate perfectly with the underlying asset, rate or index, and the Fund
  could lose more than the principal amount invested. An investment in           
  derivatives may not perform as anticipated by the Sub-Adviser, may not be able
  to be closed out at a favorable time or price. An investment in derivatives may
  also increase the Fund's volatility and create investment leverage. When a     
  derivative is used as a substitute or alternative to a direct cash investment,
  the transaction may not provide a return that corresponds precisely with that  
  of the cash investment; or, when used for hedging purposes, derivatives may not
  provide the anticipated protection, causing the Fund to lose money on both the
  derivatives transaction and the exposure the Fund sought to hedge.             
  
· Extension Risk. When interest rates rise, certain obligations will be paid off
  by the obligor more slowly than anticipated, causing the value of these        
  securities to fall.                                                            
  
· Foreign Investing Risk. The securities of foreign issuers may be less liquid   
  and more volatile than securities of comparable U.S. issuers. Investments in   
  securities of foreign issuers, even those publicly traded in the United States,
  may involve risks which are in addition to those inherent in domestic          
  investments. Foreign companies may not be subject to the same regulatory       
  requirements of U.S. companies, and as a consequence, there may be less        
  publicly available information about such companies. Also, foreign companies   
  may not be subject to uniform accounting, auditing, and financial reporting    
  standards and requirements comparable to those applicable to U.S. companies.   
  Foreign governments and foreign economies often are less stable than the U.S.  
  Government and the U.S. economy.                                               

· Interest Rate Risk. In general, the value of bonds and other debt securities   
  falls when interest rates rise. Generally, the longer the duration of a debt   
  security, the greater is the negative effect on its value when rates increase.
  Because zero coupon debt securities do not pay interest, the market value of   
  such securities can fall more dramatically than interest-paying securities of  
  similar maturities when interest rates rise. While bonds and other debt        
  securities normally fluctuate less in price than common stocks, there have been
  extended periods of increases in interest rates that have caused significant   
  declines in bond prices.                                                       

· Management Risk. The Fund is subject to management risk because it is an       
  actively managed portfolio. The portfolio manager's management practices,      
  investment strategies, and choice of investments might not work to produce the
  desired results and the Fund might underperform other comparable funds.        
  
· Market Risk. The prices of the securities in which the 2016 (1942-1947) Fund   
  invests may decline for a number of reasons including in response to economic  
  developments and perceptions about the creditworthiness of individual          
  issuers. Longer-term bonds, in which the Fund will invest a majority of its    
  assets, are generally more volatile.                                           
  
· New Fund Risk. The 2016 (1942-1947) Fund is new with no operating history and  
  there can be no assurance that the Fund will grow to or maintain an            
  economically viable size. If the Fund does not grow to or maintain an          
  economically viable size the Board may consider various alternatives, including
  the liquidation of the Fund or the merger of the Fund into another mutual fund.
· Portfolio Duration Target Formula Risk. There is no guarantee that adherence to
  the portfolio duration target formula will result in the Fund achieving its    
  investment objective.                                                          
  
· Prepayment Risk. When interest rates fall, certain obligations will be paid off
  by the obligor more quickly than originally anticipated, and the 2016          
  (1942-1947) Fund may have to invest the proceeds in securities with lower      
  yields (this is known as Reinvestment Risk).                                   
  
· Termination Risk. Because the 2016 (1942-1947) Fund has a Termination Date and
  it will invest a majority of its assets in securities that mature after the    
  Termination Date, the Fund may incur liquidation costs to liquidate its        
  portfolio.                                                                     
  
· U.S. Government Issuer Risk. Treasury obligations may differ in their interest
  rates, maturities, times of issuance and other characteristics. Obligations of
  U.S. Government agencies and authorities are supported by varying degrees of   
  credit but generally are not backed by the full faith and credit of the U.S.   
  Government. No assurance can be given that the U.S. Government will provide    
  financial support to its agencies and authorities if it is not obligated by law
  to do so.

Performance

When the 2016 (1942-1947) Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2016 (b.1942-1947) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra DFA U.S. CORE Equity Fund (Prospectus Summary) | Symetra DFA U.S. CORE Equity Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra DFA U.S. CORE Equity Fund
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra DFA U.S. CORE Equity Fund (the "U.S. CORE Equity Fund" or the "Fund") seeks long term capital appreciation.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the U.S. CORE Equity Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The U.S. CORE Equity Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" and acquired fund fees and expenses ("AFFE") are each based on estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the U.S. CORE Equity Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	Under normal market conditions, the U.S. CORE Equity Fund pursues its objective by investing at least 80% of its net assets in a broad and diverse group of exchange-traded equity securities of U.S. issuers, or other investment companies advised by the sub-adviser that invest in such issuers (the "Underlying Funds"), with an emphasis on value stocks and small capitalization securities, relative to their representation in the U.S. Universe, as defined below. Although the Fund invests in securities of companies in all market sectors and capitalization ranges, it usually is underweighted in the largest growth companies relative to the universe of exchange-traded equity securities of U.S. issuers ("U.S. Universe"). (For this purpose, a growth company is generally one that has a low book value relative to the market capitalization of its stock, whereas a value company is generally one that has a high book value relative to the market capitalization of its stock. The Sub-Adviser also may characterize a company as growth or value using other measures such as price-to-cash flow or price-to-earnings ratios, or other factors such as economic conditions or developments in the issuer's industry.) The Fund's increased exposure to small and value companies may be achieved by decreasing the allocation of the Fund's assets to the largest U.S. growth companies relative to their weight in the U.S. Universe, which would result in a greater weight allocation to small capitalization and value companies. In order to implement the U.S. Core Equity Fund's investment strategies in a cost-effective manner and achieve greater diversification than the Fund could otherwise economically achieve given its asset size, the U.S. CORE Equity Fund may invest anywhere between 0% and 40% of its assets in Underlying Funds. Initially, the U.S. CORE Equity Fund may invest in one or more Underlying Funds that purchase a broad and diverse portfolio of exchange-traded equity securities of U.S. issuers. These Underlying Funds may emphasize small capitalization companies, value companies, or both types of companies. The U.S. CORE Equity Fund may take long positions in futures contracts on stock indices and options on such futures contracts, as well as swap agreements and other derivatives in order to obtain market exposure for cash and cash equivalents in its portfolio, but otherwise will not invest in derivatives.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the U.S. CORE Equity Fund. The following additional risks could affect the value of your investment: · Derivatives Risk. Derivatives are securities, such as futures contracts, whose   value is derived from that of other securities or indices. The use of             derivatives for non-hedging purposes may be considered more speculative than      other types of investments. When the U.S. CORE Equity Fund or an Underlying       Fund uses derivatives, the Fund will be directly exposed to the risks of that     derivative. Derivative securities are subject to a number of risks including      liquidity, interest rate, market, credit and management risks, and the risk of   improper valuation. Changes in the value of the derivative may not correlate      perfectly with the underlying asset, rate or index, and the Fund or an            Underlying Fund could lose more than the principal amount invested.             · Management Risk. The U.S. CORE Equity Fund and the Underlying Funds are subject   to management risk because they are actively managed portfolios. The portfolio   managers' management practices, investment strategies, and choice of              investments might not work to produce the desired results and the Fund or an      Underlying Fund might underperform other comparable funds.                      · Market Risk. The prices of the securities in which the U.S. CORE Equity Fund or   an Underlying Fund invests may decline for a number of reasons including in       response to economic or political developments and perceptions about the          creditworthiness of individual issuers or other issuer-specific events. The       price declines of common stocks, in particular, may be steep, sudden and/or       prolonged.                                                                      · New Fund Risk. The U.S. CORE Equity Fund is new with no operating history and     there can be no assurance that the Fund will grow to or maintain an               economically viable size. If the Fund does not grow to or maintain an             economically viable size the Board may consider various alternatives, including   the liquidation of the Fund or the merger of the Fund into another mutual fund. · Other Investment Companies Risk. The investment performance of the U.S. CORE      Equity Fund will be affected by the investment performance of the Underlying      Funds in which the U.S. CORE Equity Fund invests. The ability of the U.S. CORE   Equity Fund to achieve its investment objective will depend in part on the        ability of the Underlying Funds to meet their investment objectives and on the   Sub-Adviser's decisions regarding the portion of the U.S. CORE Equity Fund's      assets that are allocated to the Underlying Funds. The U.S. CORE Equity Fund      may allocate assets to an Underlying Fund or asset class that underperforms       other funds or asset classes. There can be no assurance that the investment       objective of the U.S. CORE Equity Fund or any Underlying Fund will be achieved.    · Smaller Capitalization Companies Risk. Smaller capitalization companies           typically have relatively lower revenues, limited product lines and lack of       management depth, and may have a smaller share of the market for their products   or services, than larger capitalization companies. In general, smaller            capitalization companies are also more vulnerable than larger companies to        adverse business or economic developments. The stocks of smaller capitalization   companies tend to be less liquid and have less trading volume than stocks of      larger capitalization companies and this could make it difficult to sell          securities of smaller capitalization companies at a desired time or price. As a   result, small company stocks may fluctuate relatively more in price. Finally,     there are periods when investing in smaller capitalization stocks falls out of   favor with investors and the stocks of smaller-capitalization companies           underperform.                                                                   · Value Investing Risk. Value stocks may perform differently from the market as a   whole and following a value-oriented investment strategy may cause the U.S.       CORE Equity Fund or an Underlying Fund to at times underperform equity funds      that use other investment strategies.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the U.S. CORE Equity Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the U.S. CORE Equity Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the U.S. CORE Equity Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-796-3872
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra DFA U.S. CORE Equity Fund (Prospectus Summary) | Symetra DFA U.S. CORE Equity Fund | Symetra DFA U.S. CORE Equity Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.42%
Other Expenses	rr_OtherExpensesOverAssets	1.41%	[1]
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.07%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.90%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.33%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.57%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	58
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	467

[1] "Other expenses" and acquired fund fees and expenses ("AFFE") are each based on estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, AFFE, and extraordinary expenses) to 0.13% of the average daily net assets of the U.S. Core Equity Fund (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
Document Type	dei_DocumentType	Other
Document Period End Date	dei_DocumentPeriodEndDate	Jun. 30, 2012
Registrant Name	dei_EntityRegistrantName	Symetra Mutual Funds Trust
Central Index Key	dei_EntityCentralIndexKey	0001538307
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Jun. 04, 2012
Document Effective Date	dei_DocumentEffectiveDate	Jun. 04, 2012

XML

Symetra DFA International CORE Equity Fund (Prospectus Summary) | Symetra DFA International CORE Equity Fund

Symetra DFA International CORE Equity Fund

Investment Objective

The Symetra DFA International CORE Equity Fund (the "International Fund" or the
"Fund") seeks long term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the International Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity or variable life insurance contract level. If
those additional fees and expenses were included, overall expenses would be
higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra DFA International CORE Equity Fund
Management Fees		0.60%
Other Expenses	[1]	1.31%
Acquired Fund Fees and Expenses	[1]	0.19%
Total Annual Fund Operating Expenses		2.10%
Less: Fee Waiver and Expense Reimbursement	[2]	(1.22%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.88%

Example

This Example is intended to help you compare the cost of investing in the
International Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated and
then redeem all of your shares at the end of those periods. The Example also
assumes that your investment has a 5% return each year and that the Fund's
operating expenses remain the same (taking into account the Expense Cap and Fee
Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra DFA International CORE Equity Fund	90	540

Portfolio Turnover

The International Fund pays transaction costs, such as commissions, when it buys
and sells securities (or "turns over" its portfolio). A higher portfolio
turnover rate may indicate higher transaction costs and may result in higher
taxes when Fund shares are held in a taxable account. These costs, which are not
reflected in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Fund

Under normal market conditions, the International Fund pursues its objective by
investing at least 80% of its net assets in equity securities or in other
investment companies advised by the sub-adviser that invest in equity securities
(the "Underlying Funds"). The Fund invests in a broad and diverse group of
equity securities of foreign issuers, associated with developed markets, as
determined by the Sub-Adviser ("International Universe"), with an emphasis on
value stocks and small capitalization securities relative to the International
Universe. Although the Fund invests in securities of companies in all market
sectors and capitalization ranges, it usually is underweighted in the largest
growth companies relative to the International Universe. (For this purpose, a
growth company is generally one that has a low book value relative to the market
capitalization of its stock, whereas a value company is generally one that has a
high book value relative to the market capitalization of its stock. The
Sub-Adviser also may characterize a company as growth or value using other
measures such as price-to-cash flow or price-to-earnings ratios, or other
factors such as economic conditions or developments in the issuer's
industry.) The Fund's increased exposure to small and value companies may be
achieved by decreasing the allocation of the Fund's assets to the largest U.S.
growth companies relative to their weight in the U.S. Universe, which would
result in a greater weight allocation to small capitalization and value
companies. Under normal market conditions, the Fund, either directly or through
the Underlying Funds, maintains at least 40% of its assets in securities of
issuers representing three or more foreign countries.
  
In order to achieve greater diversification of investments than the Fund could
otherwise achieve given its size, the International Fund may invest anywhere
between 0% and 40% of its assets in Underlying Funds. The International Fund may
invest in Underlying Funds that invest in a broad and diverse group of equity
securities of foreign issuers, with an emphasis on value stocks and small
capitalization securities. Initially, the International Fund expects to invest
in international equity Underlying Funds that purchase a broad portfolio of
stocks of companies in non-U.S. developed markets of all market capitalization
sizes with an emphasis on small capitalization companies, value companies, or
both types of companies.

The International Fund may take long positions in futures contracts on stock
indices and options on such futures contracts, as well as swap agreements and
other derivatives in order to obtain market exposure for cash and cash
equivalents in its portfolio, but otherwise will not invest in derivatives.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the
International Fund. The following additional risks could affect the value of
your investment:

· Derivatives Risk. Derivatives are securities, such as futures contracts, whose
  value is derived from that of other securities or indices. The use of          
  derivatives for non-hedging purposes may be considered more speculative than   
  other types of investments. When the International Fund or an Underlying Fund  
  uses derivatives, the Fund will be directly exposed to the risks of that       
  derivative. Derivative securities are subject to a number of risks including   
  liquidity, interest rate, market, credit and management risks, and the risk of
  improper valuation. Changes in the value of the derivative may not correlate   
  perfectly with the underlying asset, rate or index, and the Fund or an         
  Underlying Fund could lose more than the principal amount invested.            

· Foreign Investing Risk. The securities of foreign issuers may be less liquid   
  and more volatile than securities of comparable U.S. issuers. The costs        
  associated with securities transactions are often higher in foreign countries  
  than the U.S. The U.S. dollar value of securities of foreign issuers traded in
  foreign currencies (and any dividends and interest earned) held by the         
  International Fund or an Underlying Fund may be affected favorably or          
  unfavorably by changes in foreign currency exchange rates. An increase in the  
  U.S. dollar relative to these other currencies will adversely affect the Fund  
  (this is known as Foreign Currency Risk). The Fund does not hedge foreign      
  currency risk. Additionally, investments in securities of foreign issuers, even
  those publicly traded in the United States, may involve risks which are in     
  addition to those inherent in domestic investments. Foreign companies may not  
  be subject to the same regulatory requirements of U.S. companies, and as a     
  consequence, there may be less publicly available information about such       
  companies. Also, foreign companies may not be subject to uniform accounting,   
  auditing, and financial reporting standards and requirements comparable to     
  those applicable to U.S. companies. Foreign governments and foreign economies  
  often are less stable than the U.S. Government and the U.S. economy.           

· Management Risk. The International Fund and the Underlying Funds are subject to
  management risk because they are actively managed portfolios. The portfolio    
  managers' management practices, investment strategies, and choice of           
  investments might not work to produce the desired results and the Fund might   
  underperform other comparable funds.                                           
  
· Market Risk. The prices of the securities in which the International Fund or an
  Underlying Fund invests may decline for a number of reasons including in       
  response to economic or political developments and perceptions about the       
  creditworthiness of individual issuers or other issuer-specific events. The    
  price declines of common stocks, in particular, may be steep, sudden and/or    
  prolonged.                                                                     

· New Fund Risk. The International Fund is new with no operating history and     
  there can be no assurance that the Fund will grow to or maintain an            
  economically viable size. If the Fund does not grow to or maintain an          
  economically viable size the Board may consider various alternatives, including
  the liquidation of the Fund or the merger of the Fund into another mutual fund.

· Other Investment Companies Risk. The investment performance of the             
  International Fund will be affected by the investment performance of the       
  Underlying Funds in which the International Fund invests. The ability of the   
  International Fund to achieve its investment objective will depend in part on  
  the ability of the Underlying Funds to meet their investment objectives and on
  the Sub-Adviser's decisions regarding the portion of the International Fund's  
  assets that are allocated to the Underlying Funds. The International Fund may  
  allocate assets to an Underlying Fund or asset class that underperforms other  
  funds or asset classes. There can be no assurance that the investment objective
  of the International Fund or any Underlying Fund will be achieved.             

· Securities Lending Risk. Securities lending involves the risk that the borrower
  may fail to return the securities in a timely manner or at all. As a result,   
  the International Fund or an Underlying Fund may lose money and there may be a
  delay in recovering the loaned securities. The Fund or an Underlying Fund could
  also lose money if it does not recover the securities and/or the value of the  
  collateral falls, including the value of investments made with cash collateral.

· Smaller Capitalization Companies Risk. Smaller capitalization companies        
  typically have relatively lower revenues, limited product lines and lack of    
  management depth, and may have a smaller share of the market for their products
  or services, than larger capitalization companies. In general, smaller         
  capitalization companies are also more vulnerable than larger companies to     
  adverse business or economic developments. The stocks of smaller capitalization
  companies tend to be less liquid and have less trading volume than stocks of   
  larger capitalization companies and this could make it difficult to sell       
  securities of smaller capitalization companies at a desired time or price. As a
  result, small company stocks may fluctuate relatively more in price. Finally,  
  there are periods when investing in smaller capitalization stocks falls out of
  favor with investors and the stocks of smaller-capitalization companies        
  underperform.                                                                  

· Value Investing Risk. Value stocks may perform differently from the market as a
  whole and following a value-oriented investment strategy may cause the         
  International Fund or an Underlying Fund to at times underperform equity funds
  that use other investment strategies.

Performance

When the International Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" and acquired fund fees and expenses ("AFFE") are each based on estimated amounts for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, AFFE, and extraordinary expenses) to 0.14% of the average daily net assets of the International CORE Equity Fund (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra Yacktman Focused Fund (Prospectus Summary) | Symetra Yacktman Focused Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra Yacktman Focused Fund
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra Yacktman Focused Fund ("Focused Fund" or the "Fund") seeks long-term capital appreciation and, to a lesser extent, income.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Focused Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The Focused Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" is an estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Focused Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	Under normal market conditions, the Focused Fund pursues its investment objective by investing a majority of its assets in common stock of U.S. issuers. Some, but not all, Fund holdings may pay dividends. The Sub-Adviser seeks to purchase "growth" oriented issuers at low prices relative to value. Through this approach, it attempts to combine the best features of "growth" and "value" investing. The Fund is a non-diversified fund and generally will hold securities of fewer issuers than the typical equity mutual fund. Consistent with this, although the Fund invests in issuers of any size market capitalization, the Sub-Adviser prefers larger companies to smaller ones.    The Focused Fund may invest up to 20% of its assets in equity securities of foreign issuers. This 20% limit does not apply to investments in the form of American Depositary Receipts ("ADRs"). The Fund may also invest up to 20% of its assets in debt securities, including lower-rated securities (commonly referred to as junk bonds). The Fund does not seek to align itself with any benchmark, but rather is opportunistic in seeking attractively-priced securities that represent predictable, quality investments, while protecting capital. As a result, the Fund may experience periods when it is very selective about investments and hold more cash than other equity mutual funds. Consistent with this, the Fund may underperform its peers in strong equity markets and outperform them in weaker markets. The Sub-Adviser generally looks for issuers with one or more of the following characteristics: (1) sound business prospects, (2) shareholder-oriented management, and (3) securities with a low purchase price. In the Sub-Adviser's view: ·   Companies with sound business prospects exhibit one or more of the following     characteristics: (a) high market share in principal product/service lines,        (b) high cash return on tangible assets, (c) relatively low capital               requirements resulting in cash flow during growth periods, (d) long product       cycles combined with short customer purchase cycles, and (e) unique franchise     characteristics.                                                              ·   Companies with shareholder oriented management exhibit one or more of the         following characteristics: (a) reinvest in the business yet generate excess       cash, (b) make synergistic acquisitions, and (c) purchase their own stock         when its price is low.                                                                                                                                          ·   A company has an attractively low stock price if the price has either of the     following characteristics: (a) the market capitalization is less than what        the Sub-Adviser would pay for the entire company, or (b) the price is             volatile and not correlated with changes in the company's fundamental             performance.                                                                  The Focused Fund sells companies that no longer meet its investment criteria, or if better investment opportunities are available.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the Focused Fund. The following additional risks could affect the value of your investment: ·   Credit Risk. The issuers of the bonds and other debt securities held by the       Focused Fund may not be able to make interest or principal payments when          due. Even if these issuers are able to make interest or principal payments,       changes in an issuer's credit rating or the market's perception of an             issuer's creditworthiness may also affect the value of the Fund's investment     in that issuer by leading to greater volatility in the price of the security. ·   Interest Rate Risk. In general, the value of bonds and other debt securities     falls when interest rates rise. Generally, the longer the duration of a debt     security, the greater is the negative effect on its value when rates              increase. While bonds and other debt securities normally fluctuate less in        price than common stocks, there have been extended periods of increases in        interest rates that have caused significant declines in bond prices.          ·   Foreign Investing Risk. The securities of foreign issuers may be less liquid     and more volatile than securities of comparable U.S. issuers. The costs           associated with securities transactions are often higher in foreign countries     than the U.S. The U.S. dollar value of securities of foreign issuers traded       in foreign currencies (and any dividends and interest earned) held by the         Focused Fund may be affected favorably or unfavorably by changes in foreign       currency exchange rates. An increase in the U.S. dollar relative to these         other currencies will adversely affect the Fund (this is known as Foreign         Currency Risk). The Fund does not hedge foreign currency risk. Additionally,     investments in securities of foreign issuers, even those publicly traded in       the United States, may involve risks which are in addition to those inherent     in domestic investments. Foreign companies may not be subject to the same         regulatory requirements of U.S. companies, and as a consequence, there may be     less publicly available information about such companies. Also, foreign           companies may not be subject to uniform accounting, auditing, and financial       reporting standards and requirements comparable to those applicable to U.S.       companies. Foreign governments and foreign economies often are less stable        than the U.S. Government and the U.S. economy.                                   ·   Junk Bond Risk. Although junk bonds generally pay higher rates of interest        than investment grade bonds, junk bonds are high risk investments that may        cause income and principal losses for the Focused Fund. Junk bonds are            subject to reduced creditworthiness of issuers; increased risk of default and     a more limited and less liquid secondary market than higher rated securities;     and greater price volatility and risk of loss of income and principal than        are higher rated securities.                                                  ·   Management Risk. The Focused Fund is subject to management risk because it is     an actively managed portfolio. The portfolio managers' management practices,     investment strategies, and choice of investments might not work to produce        the desired results and the Fund might underperform other comparable funds.   ·   Market Risk. The prices of the securities in which the Fund invests may           decline for a number of reasons including in response to economic or              political developments and perceptions about the creditworthiness of              individual issuers or other issuer-specific events. The price declines of         common stocks, in particular, may be steep, sudden and/or prolonged.          ·   New Fund Risk. The Focused Fund is new with no operating history and there        can be no assurance that the Fund will grow to or maintain an economically        viable size. If the Fund does not grow to or maintain an economically viable     size, the Board may consider various alternatives, including the liquidation     of the Fund or the merger of the Fund into another mutual fund.               ·   Non-Diversification Risk. The Focused Fund is a non-diversified investment        company. As such, it will likely invest in fewer securities than diversified     investment companies and its performance may be more volatile. The Fund may       be more susceptible to any single economic, political or regulatory event         than a more diversified fund. If the securities in which the Fund invests         perform poorly, the Fund could incur greater losses than it would have had it     invested in a greater number of securities.                                   ·   Smaller Capitalization Companies Risk. Smaller capitalization companies           typically have relatively lower revenues, limited product lines and lack of       management depth, and may have a smaller share of the market for their            products or services, than larger capitalization companies. In general,           smaller capitalization companies are also more vulnerable than larger             companies to adverse business or economic developments. The stocks of smaller     capitalization companies tend to be less liquid and have less trading volume     than stocks of larger capitalization companies and this could make it             difficult to sell securities of smaller capitalization companies at a desired     time or price. As a result, small company stocks may fluctuate relatively         more in price. Finally, there are periods when investing in smaller               capitalization stocks falls out of favor with investors and the stocks of         smaller-capitalization companies underperform.                                ·   Value Investing Risk. Value stocks may perform differently from the market as     a whole and following a value-oriented investment strategy may cause the          Focused Fund to at times underperform equity funds that use other investment     strategies.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the Focused Fund.
Risk, Nondiversified Status	rr_RiskNondiversifiedStatus	The Focused Fund is a non-diversified investment company. As such, it will likely invest in fewer securities than diversified investment companies and its performance may be more volatile. The Fund may be more susceptible to any single economic, political or regulatory event than a more diversified fund. If the securities in which the Fund invests perform poorly, the Fund could incur greater losses than it would have had it invested in a greater number of securities.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the Focused Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the Focused Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-SYMETRA (1-800-796-3872)
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra Yacktman Focused Fund (Prospectus Summary) | Symetra Yacktman Focused Fund | Symetra Yacktman Focused Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	1.47%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.47%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.40%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	1.07%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	109
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	636

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.12% of the average daily net assets of the Focused Fund (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Symetra DFA U.S. CORE Equity Fund (Prospectus Summary) | Symetra DFA U.S. CORE Equity Fund

Symetra DFA U.S. CORE Equity Fund

Investment Objective

The Symetra DFA U.S. CORE Equity Fund (the "U.S. CORE Equity Fund" or the "Fund")
seeks long term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the U.S. CORE Equity Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity or variable life insurance contract level. If
those additional fees and expenses were included, overall expenses would be
higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra DFA U.S. CORE Equity Fund
Management Fees		0.42%
Other Expenses	[1]	1.41%
Acquired Fund Fees and Expenses	[1]	0.07%
Total Annual Fund Operating Expenses		1.90%
Less: Fee Waiver and Expense Reimbursement	[2]	(1.33%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.57%

Example

This Example is intended to help you compare the cost of investing in the U.S.
CORE Equity Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated and
then redeem all of your shares at the end of those periods. The Example also
assumes that your investment has a 5% return each year and that the Fund's
operating expenses remain the same (taking into account the Expense Cap and Fee
Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra DFA U.S. CORE Equity Fund	58	467

Portfolio Turnover

The U.S. CORE Equity Fund pays transaction costs, such as commissions, when it
buys and sells securities (or "turns over" its portfolio). A higher portfolio
turnover rate may indicate higher transaction costs and may result in higher
taxes when Fund shares are held in a taxable account. These costs, which are not
reflected in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Fund

Under normal market conditions, the U.S. CORE Equity Fund pursues its objective
by investing at least 80% of its net assets in a broad and diverse group of
exchange-traded equity securities of U.S. issuers, or other investment companies
advised by the sub-adviser that invest in such issuers (the "Underlying Funds"),
with an emphasis on value stocks and small capitalization securities, relative
to their representation in the U.S. Universe, as defined below. Although the
Fund invests in securities of companies in all market sectors and capitalization
ranges, it usually is underweighted in the largest growth companies relative to
the universe of exchange-traded equity securities of U.S. issuers ("U.S.
Universe"). (For this purpose, a growth company is generally one that has a low
book value relative to the market capitalization of its stock, whereas a value
company is generally one that has a high book value relative to the market
capitalization of its stock. The Sub-Adviser also may characterize a company as
growth or value using other measures such as price-to-cash flow or
price-to-earnings ratios, or other factors such as economic conditions or
developments in the issuer's industry.) The Fund's increased exposure to small
and value companies may be achieved by decreasing the allocation of the Fund's
assets to the largest U.S. growth companies relative to their weight in the U.S.
Universe, which would result in a greater weight allocation to small
capitalization and value companies.

In order to implement the U.S. Core Equity Fund's investment strategies in a
cost-effective manner and achieve greater diversification than the Fund could
otherwise economically achieve given its asset size, the U.S. CORE Equity Fund may
invest anywhere between 0% and 40% of its assets in Underlying Funds. Initially, the
U.S. CORE Equity Fund may invest in one or more Underlying Funds that purchase a broad
and diverse portfolio of exchange-traded equity securities of U.S. issuers. These
Underlying Funds may emphasize small capitalization companies, value companies,
or both types of companies.

The U.S. CORE Equity Fund may take long positions in futures contracts on stock
indices and options on such futures contracts, as well as swap agreements and
other derivatives in order to obtain market exposure for cash and cash
equivalents in its portfolio, but otherwise will not invest in derivatives.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the U.S.
CORE Equity Fund. The following additional risks could affect the value of your
investment:

· Derivatives Risk. Derivatives are securities, such as futures contracts, whose
  value is derived from that of other securities or indices. The use of          
  derivatives for non-hedging purposes may be considered more speculative than   
  other types of investments. When the U.S. CORE Equity Fund or an Underlying    
  Fund uses derivatives, the Fund will be directly exposed to the risks of that  
  derivative. Derivative securities are subject to a number of risks including   
  liquidity, interest rate, market, credit and management risks, and the risk of
  improper valuation. Changes in the value of the derivative may not correlate   
  perfectly with the underlying asset, rate or index, and the Fund or an         
  Underlying Fund could lose more than the principal amount invested.            

· Management Risk. The U.S. CORE Equity Fund and the Underlying Funds are subject
  to management risk because they are actively managed portfolios. The portfolio
  managers' management practices, investment strategies, and choice of           
  investments might not work to produce the desired results and the Fund or an   
  Underlying Fund might underperform other comparable funds.                     

· Market Risk. The prices of the securities in which the U.S. CORE Equity Fund or
  an Underlying Fund invests may decline for a number of reasons including in    
  response to economic or political developments and perceptions about the       
  creditworthiness of individual issuers or other issuer-specific events. The    
  price declines of common stocks, in particular, may be steep, sudden and/or    
  prolonged.                                                                     

· New Fund Risk. The U.S. CORE Equity Fund is new with no operating history and  
  there can be no assurance that the Fund will grow to or maintain an            
  economically viable size. If the Fund does not grow to or maintain an          
  economically viable size the Board may consider various alternatives, including
  the liquidation of the Fund or the merger of the Fund into another mutual fund.

· Other Investment Companies Risk. The investment performance of the U.S. CORE   
  Equity Fund will be affected by the investment performance of the Underlying   
  Funds in which the U.S. CORE Equity Fund invests. The ability of the U.S. CORE
  Equity Fund to achieve its investment objective will depend in part on the     
  ability of the Underlying Funds to meet their investment objectives and on the
  Sub-Adviser's decisions regarding the portion of the U.S. CORE Equity Fund's   
  assets that are allocated to the Underlying Funds. The U.S. CORE Equity Fund   
  may allocate assets to an Underlying Fund or asset class that underperforms    
  other funds or asset classes. There can be no assurance that the investment    
  objective of the U.S. CORE Equity Fund or any Underlying Fund will be achieved.
  
· Smaller Capitalization Companies Risk. Smaller capitalization companies        
  typically have relatively lower revenues, limited product lines and lack of    
  management depth, and may have a smaller share of the market for their products
  or services, than larger capitalization companies. In general, smaller         
  capitalization companies are also more vulnerable than larger companies to     
  adverse business or economic developments. The stocks of smaller capitalization
  companies tend to be less liquid and have less trading volume than stocks of   
  larger capitalization companies and this could make it difficult to sell       
  securities of smaller capitalization companies at a desired time or price. As a
  result, small company stocks may fluctuate relatively more in price. Finally,  
  there are periods when investing in smaller capitalization stocks falls out of
  favor with investors and the stocks of smaller-capitalization companies        
  underperform.                                                                  

· Value Investing Risk. Value stocks may perform differently from the market as a
  whole and following a value-oriented investment strategy may cause the U.S.    
  CORE Equity Fund or an Underlying Fund to at times underperform equity funds   
  that use other investment strategies.

Performance

When the U.S. CORE Equity Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" and acquired fund fees and expenses ("AFFE") are each based on estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, AFFE, and extraordinary expenses) to 0.13% of the average daily net assets of the U.S. Core Equity Fund (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Symetra Pension Reserve Fund 2020 (b. 1958-1962) (Prospectus Summary) | Symetra Pension Reserve Fund 2020 (b. 1958-1962)

Symetra Pension Reserve Fund - 2020 (b.1958-1962)

Investment Objective

The Symetra Pension Reserve Fund - 2020 (b.1958-1962) (the "2020 (1958-1962)
Fund" or the "Fund") seeks investment returns that would provide an amount on
the Fund's termination date approximately equal to the then present value of
specified lifetime annuity payments to be made to investors born in the year
range identified in the Fund's name. As a result of its investment objective,
a Pension Reserve Fund may not be a wise investment choice for an investor who
does not anticipate applying his or her accumulation to the purchase of a
lifetime annuity on or shortly after the Fund's termination date.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the 2020 (1958-1962) Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity or variable life insurance contract level. If
those additional fees and expenses were included, overall expenses would be
higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra Pension Reserve Fund 2020 (b. 1958-1962)
Management Fees		0.32%
Other Expenses	[1]	1.77%
Total Annual Fund Operating Expenses		2.09%
Less: Fee Waiver and Expense Reimbursement	[2]	(1.69%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.40%

Example

This Example is intended to help you compare the cost of investing in the 2020
(1958-1962) Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated and
then redeem all of your shares at the end of those periods. The Example also
assumes that your investment has a 5% return each year and that the Fund's
operating expenses remain the same (taking into account the Expense Cap and Fee
Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra Pension Reserve Fund 2020 (b. 1958-1962)	41	491

Portfolio Turnover

The 2020 (1958-1962) Fund pays transaction costs, such as commissions, when it
buys and sells securities (or "turns over" its portfolio). A higher portfolio
turnover rate may indicate higher transaction costs and may result in higher
taxes when Fund shares are held in a taxable account. These costs, which are not
reflected in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Fund

The 2020 (1958-1962) Fund invests primarily in government securities and
dollar-denominated corporate debt securities rated, at the time of purchase,
in the three highest categories by an NRSRO or unrated securities that the
Sub-Adviser determines are of comparable quality. The Fund also may invest in
other types of dollar-denominated investment grade debt securities, including
money market instruments and securities of foreign issuers. Most of the
securities held by the Fund are zero coupon debt securities. Under normal market
conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring
government securities and dollar-denominated corporate debt securities rated, at
the time of purchase, in the two highest categories by an NRSRO, and investing
in other permitted investments when government securities and corporate
securities in the two highest categories are not available in sufficient
quantities at a reasonable price or are not available in optimal durations or
maturities.  The Fund also may manage portfolio duration by investing in
interest rate futures contracts, options on interest rate futures contracts,
structured notes and entering into swap agreements, provided that structured
notes and swap agreements are determined by the Sub-Adviser to pose minimal
counter-party credit risk.

The 2020 (1958-1962) Fund is managed to continuously meet portfolio duration
targets that correspond to projected payments, based on actuarially determined
survivorship rates, of a single life annuity on the life of a person born in the
year-range identified in the Fund's name. The portfolio duration targets are
recalculated at least monthly based on a formula established by the Adviser
(after consultation with Symetra Life Insurance Company ("Symetra Life")) at the
Fund's inception. The formula will not change once the Fund commences operations.
(The only variables in the formula are the amount of time remaining until each
annual projected payment of the single life annuity and the prevailing interest
rates on the recalculation date. The prevailing interest rates are derived from
the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under
normal market conditions, the Sub-Adviser seeks to meet the Fund's daily
portfolio duration target by first, to the extent that such investments are
available, investing in securities having cash flows similar to the projected
payments of the single life annuity and then by balancing investments in
securities with longer and shorter durations than the target duration. The
portfolio duration target generally declines for the Fund over the life of the
Fund, but will be substantially greater than zero at the Fund's termination
date. As a result, to meet the portfolio duration target, the Fund will likely
have an investment portfolio at its termination date of debt securities of
substantial remaining duration. This in turn, will result in the market value
of the Fund's investment portfolio at the termination date being significantly
influenced by prevailing interest rates. Generally speaking, the higher the
prevailing rates at the Fund's maturity, the less the Fund will receive from
selling its assets and the lower the prevailing rates, the more the Fund will
receive for selling its assets. Thus, the market value of such assets is
inversely related to prevailing interest rates.

The present value of a future series of payments decreases as the interest rate
on which the present value is computed increases. Therefore, on the 2020
(1958-1962) Fund's termination date the present value of the annuity payments
the investor is entitled to receive as a result of owning accumulation units in
the sub-account of the Symetra Resource Variable Account B that invests in
shares of the Fund will be less the higher the prevailing interest rates. The
Fund's adherence to the portfolio duration target formula is intended to result
in the Fund having on its termination date net assets approximately equal to the
present value of the aggregate annuity payments investors are entitled to
receive as a result of owning accumulation units in the sub-account of the
Symetra Resource Variable Account B that invests in shares of the Fund. However,
even if a Fund successfully adheres to the formula, there is no guarantee that
it will achieve this intended result or its investment objective. Although the
Fund has no current plans to close, there is no guarantee that the Fund will
continue to accept new investments until the termination date.

As of the date of this Prospectus, based on the current U.S. Treasury Zero
Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2020
(1958-1962) Fund's portfolio duration target would have been 21.1 years.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the 2020
(1958-1962) Fund. The following additional risks could affect the value of your
investment:

· Credit Risk. The issuers of the bonds and other debt securities held by the    
  2020 (1958-1962) Fund may not be able to make interest or principal payments   
  when due. Even if these issuers are able to make interest or principal         
  payments, changes in an issuer's credit rating or the market's perception of an
  issuer's creditworthiness may also affect the value of the Fund's investment in
  that issuer by leading to greater volatility in the price of the security.     
  
· Credit Default Swap Risk. In a credit default swap transaction, both the 2020
  (1958-1962) Fund and its counter-party are exposed to the risk of default by   
  the other. In addition, the terms of most credit default swap transactions     
  require little or no initial investment by the seller in relation to the       
  notional amount of the swap and the corresponding risk. Therefore, small       
  changes in the market value of the reference security or group of securities   
  may produce disproportionate and substantial losses for the seller.            

· Derivatives Risk. Derivatives are securities, such as futures contracts, whose
  value is derived from that of other securities or indices. The 2020 (1958-1962)
  Fund's investments in derivatives may pose risks in addition to those          
  associated with investing directly in securities or other investments.         
  Derivative securities are subject to a number of risks including liquidity,    
  interest rate, market, credit and management risks, the risk of improper       
  valuation, illiquidity of the derivatives, imperfect correlations with         
  underlying investments or the Fund's other portfolio holdings, lack of         
  availability and counterparty risk. Changes in the value of the derivative may
  not correlate perfectly with the underlying asset, rate or index, and the Fund
  could lose more than the principal amount invested. An investment in           
  derivatives may not perform as anticipated by the Sub-Adviser, may not be able
  to be closed out at a favorable time or price. An investment in derivatives may
  also increase the Fund's volatility and create investment leverage. When a     
  derivative is used as a substitute or alternative to a direct cash investment,
  the transaction may not provide a return that corresponds precisely with that  
  of the cash investment; or, when used for hedging purposes, derivatives may not
  provide the anticipated protection, causing the Fund to lose money on both the
  derivatives transaction and the exposure the Fund sought to hedge.             

· Extension Risk. When interest rates rise, certain obligations will be paid off
  by the obligor more slowly than anticipated, causing the value of these        
  securities to fall.                                                            

· Foreign Investing Risk. The securities of foreign issuers may be less liquid   
  and more volatile than securities of comparable U.S. issuers. Investments in   
  securities of foreign issuers, even those publicly traded in the United States,
  may involve risks which are in addition to those inherent in domestic          
  investments. Foreign companies may not be subject to the same regulatory       
  requirements of U.S. companies, and as a consequence, there may be less        
  publicly available information about such companies. Also, foreign companies   
  may not be subject to uniform accounting, auditing, and financial reporting    
  standards and requirements comparable to those applicable to U.S. companies.   
  Foreign governments and foreign economies often are less stable than the U.S.  
  Government and the U.S. economy.                                               

· Interest Rate Risk. In general, the value of bonds and other debt securities   
  falls when interest rates rise. Generally, the longer the duration of a debt   
  security, the greater is the negative effect on its value when rates           
  increase. Because zero coupon debt securities do not pay interest, the market  
  value of such securities can fall more dramatically than interest-paying       
  securities of similar maturities when interest rates rise. While bonds and     
  other debt securities normally fluctuate less in price than common stocks,     
  there have been extended periods of increases in interest rates that have      
  caused significant declines in bond prices.                                    

· Management Risk. The 2020 (1958-1962) Fund is subject to management risk       
  because it is an actively managed portfolio. The portfolio manager's management
  practices, investment strategies, and choice of investments might not work to  
  produce the desired results and the Fund might underperform other comparable   
  funds.                                                                         

· Market Risk. The prices of the securities in which the 2020 (1958-1962) Fund   
  invests may decline for a number of reasons including in response to economic  
  developments and perceptions about the creditworthiness of individual          
  issuers. Longer-term bonds, in which the Fund will invest a majority of its    
  assets, are generally more volatile.                                           

· New Fund Risk. The 2020 (1958-1962) Fund is new with no operating history and  
  there can be no assurance that the Fund will grow to or maintain an            
  economically viable size. If the Fund does not grow to or maintain an          
  economically viable size the Board may consider various alternatives, including
  the liquidation of the Fund or the merger of the Fund into another mutual fund.
  
· Portfolio Duration Target Formula Risk. There is no guarantee that adherence to
  the portfolio duration target formula will result in the Fund achieving its    
  investment objective.                                                          

· Prepayment Risk. When interest rates fall, certain obligations will be paid off
  by the obligor more quickly than originally anticipated, and the 2020          
  (1958-1962) Fund may have to invest the proceeds in securities with lower      
  yields (this is known as Reinvestment Risk).                                   

· Termination Risk. Because the 2020 (1958-1962) Fund has a Termination Date and
  it will invest a majority of its assets in securities that mature after the    
  Termination Date, the Fund may incur liquidation costs to liquidate its        
  portfolio.                                                                     

· U.S. Government Issuer Risk. Treasury obligations may differ in their interest
  rates, maturities, times of issuance and other characteristics. Obligations of
  U.S. Government agencies and authorities are supported by varying degrees of   
  credit but generally are not backed by the full faith and credit of the U.S.   
  Government. No assurance can be given that the U.S. Government will provide    
  financial support to its agencies and authorities if it is not obligated by law
  to do so.

Performance

When the 2020 (1958-1962) Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2020 (b.1958-1962) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Symetra Pension Reserve Fund 2016 (b. 1948-1952) (Prospectus Summary) | Symetra Pension Reserve Fund 2016 (b. 1948-1952)

Symetra Pension Reserve Fund - 2016 (b.1948-1952)

Investment Objective

The Symetra Pension Reserve Fund - 2016 (b.1948-1952) (the "2016 (1948-1952)
Fund" or the "Fund") seeks investment returns that would provide an amount on
the Fund's termination date approximately equal to the then present value of
specified lifetime annuity payments to be made to investors born in the year
range identified in the Fund's name. As a result of its investment objective, a
Pension Reserve Fund may not be a wise investment choice for an investor who
does not anticipate applying his or her accumulation to the purchase of a
lifetime annuity on or shortly after the Fund's termination date.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the 2016 (1948-1952) Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity or variable life insurance contract level. If
those additional fees and expenses were included, overall expenses would be
higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra Pension Reserve Fund 2016 (b. 1948-1952)
Management Fees		0.32%
Other Expenses	[1]	1.77%
Total Annual Fund Operating Expenses		2.09%
Less: Fee Waiver and Expense Reimbursement	[2]	(1.69%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.40%

Example

This Example is intended to help you compare the cost of investing in the 2016
(1948-1952) Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated and
then redeem all of your shares at the end of those periods. The Example also
assumes that your investment has a 5% return each year and that the Fund's
operating expenses remain the same (taking into account the Expense Cap and Fee
Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra Pension Reserve Fund 2016 (b. 1948-1952)	41	491

Portfolio Turnover

The 2016 (1948-1952) Fund pays transaction costs, such as commissions, when it
buys and sells securities (or "turns over" its portfolio). A higher portfolio
turnover rate may indicate higher transaction costs and may result in higher
taxes when Fund shares are held in a taxable account. These costs, which are not
reflected in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the 2016 (1948-1952) Fund

The 2016 (1948-1952) Fund invests primarily in government securities and
dollar-denominated corporate debt securities rated, at the time of purchase, in
the three highest categories by an NRSRO or unrated securities that the
Sub-Adviser determines are of comparable quality. The Fund also may invest in
other types of dollar-denominated investment debt grade securities, including
money market instruments and securities of foreign issuers. Most of the
securities held by the Fund are zero coupon debt securities. Under normal market
conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring
government securities and dollar-denominated corporate debt securities rated, at
the time of purchase, in the two highest categories by an NRSRO, and investing
in other permitted investments when government securities and corporate
securities in the two highest categories are not available in sufficient
quantities at a reasonable price or are not available in optimal durations or
maturities.  The Fund also may manage portfolio duration by investing in
interest rate futures contracts, options on interest rate futures contracts,
structured notes and entering into swap agreements, provided that structured
notes and swap agreements are determined by the Sub-Adviser to pose minimal
counter-party credit risk.

The 2016 (1948-1952) Fund is managed to continuously meet portfolio duration
targets that correspond to projected payments, based on actuarially determined
survivorship rates, of a single life annuity on the life of a person born in the
year-range identified in the Fund's name. The portfolio duration targets are
recalculated at least monthly based on a formula established by the Adviser
(after consultation with Symetra Life Insurance Company ("Symetra Life")) at the
Fund's inception. The formula will not change once the Fund commences
operations. (The only variables in the formula are the amount of time remaining
until each annual projected payment of the single life annuity and the
prevailing interest rates on the recalculation date. The prevailing interest
rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by
interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet
the Fund's daily portfolio duration target by first, to the extent that such
investments are available, investing in securities having cash flows similar to
the projected payments of the single life annuity and then by balancing
investments in securities with longer and shorter durations than the target
duration. The portfolio duration target generally declines for the Fund over the
life of the Fund, but will be substantially greater than zero at the Fund's
termination date. As a result, to meet the portfolio duration target, the Fund
will likely have an investment portfolio at its termination date of debt
securities of substantial remaining duration. This in turn, will result in the
market value of the Fund's investment portfolio at the termination date being
significantly influenced by prevailing interest rates. Generally speaking, the
higher the prevailing rates at the Fund's maturity, the less the Fund will
receive from selling its assets and the lower the prevailing rates, the more the
Fund will receive for selling its assets. Thus, the market value of such assets
is inversely related to prevailing interest rates.

The present value of a future series of payments decreases as the interest rate
on which the present value is computed increases. Therefore, on the 2016
(1948-1952) Fund's termination date the present value of the annuity payments
the investor is entitled to receive as a result of owning accumulation units in
the sub-account of the Symetra Resource Variable Account B that invests in
shares of the Fund will be less the higher the prevailing interest rates. The
Fund's adherence to the portfolio duration target formula is intended to result
in the Fund having on its termination date net assets approximately equal to the
present value of the aggregate annuity payments investors are entitled to
receive as a result of owning accumulation units in the sub-account of the
Symetra Resource Variable Account B that invests in shares of the Fund. However,
even if a Fund successfully adheres to the formula, there is no guarantee that
it will achieve this intended result or its investment objective. Although the
Fund has no current plans to close, there is no guarantee that the Fund will
continue to accept new investments until the termination date.

As of the date of this Prospectus, based on the current U.S. Treasury Zero
Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2016
(1948-1952) Fund's portfolio duration target would have been 15.5 years.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the 2016
(1948-1952) Fund. The following additional risks could affect the value of your
investment:

· Credit Risk. The issuers of the bonds and other debt securities held by the    
  2016 (1948-1952) Fund may not be able to make interest or principal payments   
  when due. Even if these issuers are able to make interest or principal         
  payments, changes in an issuer's credit rating or the market's perception of an
  issuer's creditworthiness may also affect the value of the Fund's investment in
  that issuer by leading to greater volatility in the price of the security.     

· Credit Default Swap Risk. In a credit default swap transaction, both the 2016
  (1948-1952) Fund and its counter-party are exposed to the risk of default by   
  the other. In addition, the terms of most credit default swap transactions     
  require little or no initial investment by the seller in relation to the       
  notional amount of the swap and the corresponding risk. Therefore, small       
  changes in the market value of the reference security or group of securities   
  may produce disproportionate and substantial losses for the seller.            
  
· Derivatives Risk. Derivatives are securities, such as futures contracts, whose
  value is derived from that of other securities or indices. The 2016 (1948-1952)
  Fund's investments in derivatives may pose risks in addition to those          
  associated with investing directly in securities or other investments.         
  Derivative securities are subject to a number of risks including liquidity,    
  interest rate, market, credit and management risks, the risk of improper       
  valuation, illiquidity of the derivatives, imperfect correlations with         
  underlying investments or the Fund's other portfolio holdings, lack of         
  availability and counterparty risk. Changes in the value of the derivative may
  not correlate perfectly with the underlying asset, rate or index, and the Fund
  could lose more than the principal amount invested. An investment in           
  derivatives may not perform as anticipated by the Sub-Adviser, may not be able
  to be closed out at a favorable time or price. An investment in derivatives may
  also increase the Fund's volatility and create investment leverage. When a     
  derivative is used as a substitute or alternative to a direct cash investment,
  the transaction may not provide a return that corresponds precisely with that  
  of the cash investment; or, when used for hedging purposes, derivatives may not
  provide the anticipated protection, causing the Fund to lose money on both the
  derivatives transaction and the exposure the Fund sought to hedge.             

· Extension Risk. When interest rates rise, certain obligations will be paid off
  by the obligor more slowly than anticipated, causing the value of these        
  securities to fall.                                                            

· Foreign Investing Risk. The securities of foreign issuers may be less liquid   
  and more volatile than securities of comparable U.S. issuers. Investments in   
  securities of foreign issuers, even those publicly traded in the United States,
  may involve risks which are in addition to those inherent in domestic          
  investments. Foreign companies may not be subject to the same regulatory       
  requirements of U.S. companies, and as a consequence, there may be less        
  publicly available information about such companies. Also, foreign companies   
  may not be subject to uniform accounting, auditing, and financial reporting    
  standards and requirements comparable to those applicable to U.S. companies.   
  Foreign governments and foreign economies often are less stable than the U.S.  
  Government and the U.S. economy.                                               

· Interest Rate Risk. In general, the value of bonds and other debt securities   
  falls when interest rates rise. Generally, the longer the duration of a debt   
  security, the greater is the negative effect on its value when rates           
  increase. Because zero coupon debt securities do not pay interest, the market  
  value of such securities can fall more dramatically than interest-paying       
  securities of similar maturities when interest rates rise. While bonds and     
  other debt securities normally fluctuate less in price than common stocks,     
  there have been extended periods of increases in interest rates that have      
  caused significant declines in bond prices.                                    

· Management Risk. The 2016 (1948-1952) Fund is subject to management risk       
  because it is an actively managed portfolio. The portfolio manager's management
  practices, investment strategies, and choice of investments might not work to  
  produce the desired results and the Fund might underperform other comparable   
  funds.                                                                         

· Market Risk. The prices of the securities in which the 2016 (1948-1952) Fund   
  invests may decline for a number of reasons including in response to economic  
  developments and perceptions about the creditworthiness of individual          
  issuers. Longer-term bonds, in which the Fund will invest a majority of its    
  assets, are generally more volatile.                                           

· New Fund Risk. The 2016 (1948-1952) Fund is new with no operating history and  
  there can be no assurance that the Fund will grow to or maintain an            
  economically viable size. If the Fund does not grow to or maintain an          
  economically viable size the Board may consider various alternatives, including
  the liquidation of the Fund or the merger of the Fund into another mutual fund.
  
· Portfolio Duration Target Formula Risk. There is no guarantee that adherence to
  the portfolio duration target formula will result in the Fund achieving its    
  investment objective.                                                          

· Prepayment Risk. When interest rates fall, certain obligations will be paid off
  by the obligor more quickly than originally anticipated, and the 2016          
  (1948-1952) Fund may have to invest the proceeds in securities with lower      
  yields (this is known as Reinvestment Risk).                                   

· Termination Risk. Because the 2016 (1948-1952) Fund has a Termination Date and
  it will invest a majority of its assets in securities that mature after the    
  Termination Date, the Fund may incur liquidation costs to liquidate its        
  portfolio.                                                                     

· U.S. Government Issuer Risk. Treasury obligations may differ in their interest
  rates, maturities, times of issuance and other characteristics. Obligations of
  U.S. Government agencies and authorities are supported by varying degrees of   
  credit but generally are not backed by the full faith and credit of the U.S.   
  Government. No assurance can be given that the U.S. Government will provide    
  financial support to its agencies and authorities if it is not obligated by law
  to do so.

Performance

When the 2016 (1948-1952) Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2016 (b.1948-1952) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra DFA International CORE Equity Fund (Prospectus Summary) | Symetra DFA International CORE Equity Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra DFA International CORE Equity Fund
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra DFA International CORE Equity Fund (the "International Fund" or the "Fund") seeks long term capital appreciation.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the International Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The International Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Acquired Fund Fees and Expenses, Based on Estimates	rr_AcquiredFundFeesAndExpensesBasedOnEstimates	"Other expenses" and acquired fund fees and expenses ("AFFE") are each based on estimated amounts for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the International Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	Under normal market conditions, the International Fund pursues its objective by investing at least 80% of its net assets in equity securities or in other investment companies advised by the sub-adviser that invest in equity securities (the "Underlying Funds"). The Fund invests in a broad and diverse group of equity securities of foreign issuers, associated with developed markets, as determined by the Sub-Adviser ("International Universe"), with an emphasis on value stocks and small capitalization securities relative to the International Universe. Although the Fund invests in securities of companies in all market sectors and capitalization ranges, it usually is underweighted in the largest growth companies relative to the International Universe. (For this purpose, a growth company is generally one that has a low book value relative to the market capitalization of its stock, whereas a value company is generally one that has a high book value relative to the market capitalization of its stock. The Sub-Adviser also may characterize a company as growth or value using other measures such as price-to-cash flow or price-to-earnings ratios, or other factors such as economic conditions or developments in the issuer's industry.) The Fund's increased exposure to small and value companies may be achieved by decreasing the allocation of the Fund's assets to the largest U.S. growth companies relative to their weight in the U.S. Universe, which would result in a greater weight allocation to small capitalization and value companies. Under normal market conditions, the Fund, either directly or through the Underlying Funds, maintains at least 40% of its assets in securities of issuers representing three or more foreign countries.    In order to achieve greater diversification of investments than the Fund could otherwise achieve given its size, the International Fund may invest anywhere between 0% and 40% of its assets in Underlying Funds. The International Fund may invest in Underlying Funds that invest in a broad and diverse group of equity securities of foreign issuers, with an emphasis on value stocks and small capitalization securities. Initially, the International Fund expects to invest in international equity Underlying Funds that purchase a broad portfolio of stocks of companies in non-U.S. developed markets of all market capitalization sizes with an emphasis on small capitalization companies, value companies, or both types of companies. The International Fund may take long positions in futures contracts on stock indices and options on such futures contracts, as well as swap agreements and other derivatives in order to obtain market exposure for cash and cash equivalents in its portfolio, but otherwise will not invest in derivatives.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the International Fund. The following additional risks could affect the value of your investment: · Derivatives Risk. Derivatives are securities, such as futures contracts, whose   value is derived from that of other securities or indices. The use of             derivatives for non-hedging purposes may be considered more speculative than      other types of investments. When the International Fund or an Underlying Fund     uses derivatives, the Fund will be directly exposed to the risks of that          derivative. Derivative securities are subject to a number of risks including      liquidity, interest rate, market, credit and management risks, and the risk of   improper valuation. Changes in the value of the derivative may not correlate      perfectly with the underlying asset, rate or index, and the Fund or an            Underlying Fund could lose more than the principal amount invested.             · Foreign Investing Risk. The securities of foreign issuers may be less liquid      and more volatile than securities of comparable U.S. issuers. The costs           associated with securities transactions are often higher in foreign countries     than the U.S. The U.S. dollar value of securities of foreign issuers traded in   foreign currencies (and any dividends and interest earned) held by the            International Fund or an Underlying Fund may be affected favorably or             unfavorably by changes in foreign currency exchange rates. An increase in the     U.S. dollar relative to these other currencies will adversely affect the Fund     (this is known as Foreign Currency Risk). The Fund does not hedge foreign         currency risk. Additionally, investments in securities of foreign issuers, even   those publicly traded in the United States, may involve risks which are in        addition to those inherent in domestic investments. Foreign companies may not     be subject to the same regulatory requirements of U.S. companies, and as a        consequence, there may be less publicly available information about such          companies. Also, foreign companies may not be subject to uniform accounting,      auditing, and financial reporting standards and requirements comparable to        those applicable to U.S. companies. Foreign governments and foreign economies     often are less stable than the U.S. Government and the U.S. economy.            · Management Risk. The International Fund and the Underlying Funds are subject to   management risk because they are actively managed portfolios. The portfolio       managers' management practices, investment strategies, and choice of              investments might not work to produce the desired results and the Fund might      underperform other comparable funds.                                               · Market Risk. The prices of the securities in which the International Fund or an   Underlying Fund invests may decline for a number of reasons including in          response to economic or political developments and perceptions about the          creditworthiness of individual issuers or other issuer-specific events. The       price declines of common stocks, in particular, may be steep, sudden and/or       prolonged.                                                                      · New Fund Risk. The International Fund is new with no operating history and        there can be no assurance that the Fund will grow to or maintain an               economically viable size. If the Fund does not grow to or maintain an             economically viable size the Board may consider various alternatives, including   the liquidation of the Fund or the merger of the Fund into another mutual fund. · Other Investment Companies Risk. The investment performance of the                International Fund will be affected by the investment performance of the          Underlying Funds in which the International Fund invests. The ability of the      International Fund to achieve its investment objective will depend in part on     the ability of the Underlying Funds to meet their investment objectives and on   the Sub-Adviser's decisions regarding the portion of the International Fund's     assets that are allocated to the Underlying Funds. The International Fund may     allocate assets to an Underlying Fund or asset class that underperforms other     funds or asset classes. There can be no assurance that the investment objective   of the International Fund or any Underlying Fund will be achieved.              · Securities Lending Risk. Securities lending involves the risk that the borrower   may fail to return the securities in a timely manner or at all. As a result,      the International Fund or an Underlying Fund may lose money and there may be a   delay in recovering the loaned securities. The Fund or an Underlying Fund could   also lose money if it does not recover the securities and/or the value of the     collateral falls, including the value of investments made with cash collateral. · Smaller Capitalization Companies Risk. Smaller capitalization companies           typically have relatively lower revenues, limited product lines and lack of       management depth, and may have a smaller share of the market for their products   or services, than larger capitalization companies. In general, smaller            capitalization companies are also more vulnerable than larger companies to        adverse business or economic developments. The stocks of smaller capitalization   companies tend to be less liquid and have less trading volume than stocks of      larger capitalization companies and this could make it difficult to sell          securities of smaller capitalization companies at a desired time or price. As a   result, small company stocks may fluctuate relatively more in price. Finally,     there are periods when investing in smaller capitalization stocks falls out of   favor with investors and the stocks of smaller-capitalization companies           underperform.                                                                   · Value Investing Risk. Value stocks may perform differently from the market as a   whole and following a value-oriented investment strategy may cause the            International Fund or an Underlying Fund to at times underperform equity funds   that use other investment strategies.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the International Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the International Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the International Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-SYMETRA (1-800-796-3872)
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra DFA International CORE Equity Fund (Prospectus Summary) | Symetra DFA International CORE Equity Fund | Symetra DFA International CORE Equity Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.60%
Other Expenses	rr_OtherExpensesOverAssets	1.31%	[1]
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.19%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.10%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.22%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.88%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	90
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	540

[1] "Other expenses" and acquired fund fees and expenses ("AFFE") are each based on estimated amounts for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, AFFE, and extraordinary expenses) to 0.14% of the average daily net assets of the International CORE Equity Fund (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Symetra Pension Reserve Fund 2020 (b. 1942-1947) (Prospectus Summary) | Symetra Pension Reserve Fund 2020 (b. 1942-1947)

Symetra Pension Reserve Fund - 2020 (b.1942-1947)

Investment Objective

The Symetra Pension Reserve Fund - 2020 (b.1942-1947) (the "2020 (1942-1947)
Fund" or the "Fund") seeks investment returns that would provide an amount on
the Fund's termination date approximately equal to the then present value of
specified lifetime annuity payments to be made to investors born in the year
range identified in the Fund's name. As a result of its investment objective, a
Pension Reserve Fund may not be a wise investment choice for an investor who
does not anticipate applying his or her accumulation to the purchase of a
lifetime annuity on or shortly after the Fund's termination date.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the 2020 (1942-1947) Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity or variable life insurance contract level. If
those additional fees and expenses were included, overall expenses would be
higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra Pension Reserve Fund 2020 (b. 1942-1947)
Management Fees		0.32%
Other Expenses	[1]	1.77%
Total Annual Fund Operating Expenses		2.09%
Less: Fee Waiver and Expense Reimbursement	[2]	(1.69%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.40%

Example

This Example is intended to help you compare the cost of investing in the 2020
(1942-1947) Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated and
then redeem all of your shares at the end of those periods. The Example also
assumes that your investment has a 5% return each year and that the Fund's
operating expenses remain the same (taking into account the Expense Cap and Fee
Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra Pension Reserve Fund 2020 (b. 1942-1947)	41	491

Portfolio Turnover

The 2020 (1942-1947) Fund pays transaction costs, such as commissions, when it
buys and sells securities (or "turns over" its portfolio). A higher portfolio
turnover rate may indicate higher transaction costs and may result in higher
taxes when Fund shares are held in a taxable account. These costs, which are not
reflected in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Fund

The 2020 (1942-1947) Fund invests primarily in government securities and
dollar-denominated corporate debt securities rated, at the time of purchase, in
the three highest categories by an NRSRO or unrated securities that the
Sub-Adviser determines are of comparable quality. The Fund also may invest in
other types of dollar-denominated investment grade debt securities, including
money market instruments and securities of foreign issuers. Most of the
securities held by the Fund are zero coupon debt securities. Under normal market
conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring
government securities and dollar-denominated corporate debt securities rated, at
the time of purchase, in the two highest categories by an NRSRO, and investing
in other permitted investments when government securities and corporate
securities in the two highest categories are not available in sufficient
quantities at a reasonable price or are not available in optimal durations or
maturities.  The Fund also may manage portfolio duration by investing in
interest rate futures contracts, options on interest rate futures contracts,
structured notes and entering into swap agreements, provided that structured
notes and swap agreements are determined by the Sub-Adviser to pose minimal
counter-party credit risk.

The 2020 (1942-1947) Fund is managed to continuously meet portfolio duration
targets that correspond to projected payments, based on actuarially determined
survivorship rates, of a single life annuity on the life of a person born in the
year-range identified in the Fund's name. The portfolio duration targets are
recalculated at least monthly based on a formula established by the Adviser
(after consultation with Symetra Life Insurance Company ("Symetra Life")) at the
Fund's inception. The formula will not change once the Fund commences
operations. (The only variables in the formula are the amount of time remaining
until each annual projected payment of the single life annuity and the
prevailing interest rates on the recalculation date. The prevailing interest
rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by
interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet
the Fund's daily portfolio duration target by first, to the extent that such
investments are available, investing in securities having cash flows similar to
the projected payments of the single life annuity and then by balancing
investments in securities with longer and shorter durations than the target
duration. The portfolio duration target generally declines for the Fund over the
life of the Fund, but will be substantially greater than zero at the Fund's
termination date. As a result, to meet the portfolio duration target, the Fund
will have an investment portfolio at its termination date of debt securities of
substantial remaining duration. This in turn, will result in the market value of
the Fund's investment portfolio at the termination date being significantly
influenced by prevailing interest rates. Generally speaking, the higher the
prevailing rates at the Fund's maturity, the less the Fund will receive from
selling its assets and the lower the prevailing rates, the more the Fund will
receive for selling its assets. Thus, the market value of such assets is
inversely related to prevailing interest rates.

The present value of a future series of payments decreases as the interest rate
on which the present value is computed increases. Therefore, on the 2020
(1942-1947) Fund's termination date the present value of the annuity payments
the investor is entitled to receive as a result of owning accumulation units in
the sub-account of the Symetra Resource Variable Account B that invests in
shares of the Fund will be less the higher the prevailing interest rates. The
Fund's adherence to the portfolio duration target formula is intended to result
in the Fund having on its termination date net assets approximately equal to the
present value of the aggregate annuity payments investors are entitled to
receive as a result of owning accumulation units in the sub-account of the
Symetra Resource Variable Account B that invests in shares of the Fund. However,
even if a Fund successfully adheres to the formula, there is no guarantee that
it will achieve this intended result or its investment objective. Although the
Fund has no current plans to close, there is no guarantee that the Fund will
continue to accept new investments until the termination date.

As of the date of this Prospectus, based on the current U.S. Treasury Zero
Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2020
(1942-1947) Fund's portfolio duration target would have been 16.2 years.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the 2020
(1942-1947) Fund. The following additional risks could affect the value of your
investment:

· Credit Risk. The issuers of the bonds and other debt securities held by the  
  2020 (1942-1947) Fund may not be able to make interest or principal payments
  when due. Even if these issuers are able to make interest or principal       
  payments, changes in an issuer's credit rating or the market's perception of
  an issuer's creditworthiness may also affect the value of the Fund's         
  investment in that issuer by leading to greater volatility in the price of   
  the security.                                                                
  
· Credit Default Swap Risk. In a credit default swap transaction, both the 2020
  (1942-1947) Fund and its counter-party are exposed to the risk of default by   
  the other. In addition, the terms of most credit default swap transactions     
  require little or no initial investment by the seller in relation to the       
  notional amount of the swap and the corresponding risk. Therefore, small       
  changes in the market value of the reference security or group of securities   
  may produce disproportionate and substantial losses for the seller.            
  
· Derivatives Risk. Derivatives are securities, such as futures contracts, whose
  value is derived from that of other securities or indices. The 2020 (1942-1947)
  Fund's investments in derivatives may pose risks in addition to those          
  associated with investing directly in securities or other investments.         
  Derivative securities are subject to a number of risks including liquidity,    
  interest rate, market, credit and management risks, the risk of improper       
  valuation, illiquidity of the derivatives, imperfect correlations with         
  underlying investments or the Fund's other portfolio holdings, lack of         
  availability and counterparty risk. Changes in the value of the derivative may
  not correlate perfectly with the underlying asset, rate or index, and the Fund
  could lose more than the principal amount invested. An investment in           
  derivatives may not perform as anticipated by the Sub-Adviser, may not be able
  to be closed out at a favorable time or price. An investment in derivatives may
  also increase the Fund's volatility and create investment leverage. When a     
  derivative is used as a substitute or alternative to a direct cash investment,
  the transaction may not provide a return that corresponds precisely with that  
  of the cash investment; or, when used for hedging purposes, derivatives may not
  provide the anticipated protection, causing the Fund to lose money on both the
  derivatives transaction and the exposure the Fund sought to hedge.             
  
· Extension Risk. When interest rates rise, certain obligations will be paid off
  by the obligor more slowly than anticipated, causing the value of these        
  securities to fall.                                                            
  
· Foreign Investing Risk. The securities of foreign issuers may be less liquid   
  and more volatile than securities of comparable U.S. issuers. Investments in   
  securities of foreign issuers, even those publicly traded in the United States,
  may involve risks which are in addition to those inherent in domestic          
  investments. Foreign companies may not be subject to the same regulatory       
  requirements of U.S. companies, and as a consequence, there may be less        
  publicly available information about such companies. Also, foreign companies   
  may not be subject to uniform accounting, auditing, and financial reporting    
  standards and requirements comparable to those applicable to U.S. companies.   
  Foreign governments and foreign economies often are less stable than the U.S.  
  Government and the U.S. economy.                                               
  
· Interest Rate Risk. In general, the value of bonds and other debt securities   
  falls when interest rates rise. Generally, the longer the duration of a debt   
  security, the greater is the negative effect on its value when rates           
  increase. Because zero coupon debt securities do not pay interest, the market  
  value of such securities can fall more dramatically than interest-paying       
  securities of similar maturities when interest rates rise. While bonds and     
  other debt securities normally fluctuate less in price than common stocks,     
  there have been extended periods of increases in interest rates that have      
  caused significant declines in bond prices.                                    
  
· Management Risk. The 2020 (1942-1947) Fund is subject to management risk       
  because it is an actively managed portfolio. The portfolio manager's management
  practices, investment strategies, and choice of investments might not work to  
  produce the desired results and the Fund might underperform other comparable   
  funds.                                                                         
  
· Market Risk. The prices of the securities in which the 2020 (1942-1947) Fund   
  invests may decline for a number of reasons including in response to economic  
  developments and perceptions about the creditworthiness of individual          
  issuers. Longer-term bonds, in which the Fund will invest a majority of its    
  assets, are generally more volatile.                                           
  
· New Fund Risk. The 2020 (1942-1947) Fund is new with no operating history and  
  there can be no assurance that the Fund will grow to or maintain an            
  economically viable size. If the Fund does not grow to or maintain an          
  economically viable size the Board may consider various alternatives, including
  the liquidation of the Fund or the merger of the Fund into another mutual fund.
  
· Portfolio Duration Target Formula Risk. There is no guarantee that adherence to
  the portfolio duration target formula will result in the Fund achieving its    
  investment objective.                                                          
  
· Prepayment Risk. When interest rates fall, certain obligations will be paid off
  by the obligor more quickly than originally anticipated, and the 2020          
  (1942-1947) Fund may have to invest the proceeds in securities with lower      
  yields (this is known as Reinvestment Risk).                                   
  
· Termination Risk. Because the 2020 (1942-1947) Fund has a Termination Date and
  it will invest a majority of its assets in securities that mature after the    
  Termination Date, the Fund may incur liquidation costs to liquidate its        
  portfolio.                                                                     
  
· U.S. Government Issuer Risk. Treasury obligations may differ in their interest
  rates, maturities, times of issuance and other characteristics. Obligations of
  U.S. Government agencies and authorities are supported by varying degrees of   
  credit but generally are not backed by the full faith and credit of the U.S.   
  Government. No assurance can be given that the U.S. Government will provide    
  financial support to its agencies and authorities if it is not obligated by law
  to do so.

Performance

When the 2020 (1942-1947) Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2020 (b. 1942-1947) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra Pension Reserve Fund 2028 (b. 1948-1952) (Prospectus Summary) | Symetra Pension Reserve Fund 2028 (b. 1948-1952)
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra Pension Reserve Fund - 2028 (b.1948-1952)
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra Pension Reserve Fund - 2028 (b.1948-1952) (the "2028 (1948-1952) Fund" or the "Fund") seeks investment returns that would provide an amount on the Fund's termination date approximately equal to the then present value of specified lifetime annuity payments to be made to investors born in the year range identified in the Fund's name. As a result of its investment objective, a Pension Reserve Fund may not be a wise investment choice for an investor who does not anticipate applying his or her accumulation to the purchase of a lifetime annuity on or shortly after the Fund's termination date.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the 2028 (1948-1952) Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The 2028 (1948-1952) Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" is an estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the 2028 (1948-1952) Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The 2028 (1948-1952) Fund invests primarily in government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the three highest categories by an NRSRO or unrated securities that the Sub-Adviser determines are of comparable quality. The Fund also may invest in other types of dollar-denominated investment grade debt securities, including money market instruments and securities of foreign issuers. Most of the securities held by the Fund are zero coupon debt securities. Under normal market conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the two highest categories by an NRSRO, and investing in other permitted investments when government securities and corporate securities in the two highest categories are not available in sufficient quantities at a reasonable price or are not available in optimal durations or maturities.  The Fund also may manage portfolio duration by investing in interest rate futures contracts, options on interest rate futures contracts, structured notes and entering into swap agreements, provided that structured notes and swap agreements are determined by the Sub-Adviser to pose minimal counter-party credit risk. The 2028 (1948-1952) Fund is managed to continuously meet portfolio duration targets that correspond to projected payments, based on actuarially determined survivorship rates, of a single life annuity on the life of a person born in the year-range identified in the Fund's name. The portfolio duration targets are recalculated at least monthly based on a formula established by the Adviser (after consultation with Symetra Life Insurance Company ("Symetra Life")) at the Fund's inception. The formula will not change once the Fund commences operations. (The only variables in the formula are the amount of time remaining until each annual projected payment of the single life annuity and the prevailing interest rates on the recalculation date. The prevailing interest rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet the Fund's daily portfolio duration target by first, to the extent that such investments are available, investing in securities having cash flows similar to the projected payments of the single life annuity and then by balancing investments in securities with longer and shorter durations than the target duration. The portfolio duration target generally declines for the Fund over the life of the Fund, but will be substantially greater than zero at the Fund's termination date. As a result, to meet the portfolio duration target, the Fund will likely have an investment portfolio at its termination date of debt securities of substantial remaining duration. This in turn, will result in the market value of the Fund's investment portfolio at the termination date being significantly influenced by prevailing interest rates. Generally speaking, the higher the prevailing rates at the Fund's maturity, the less the Fund will receive from selling its assets and the lower the prevailing rates, the more the Fund will receive for selling its assets. Thus, the market value of such assets is inversely related to prevailing interest rates. The present value of a future series of payments decreases as the interest rate on which the present value is computed increases. Therefore, on the 2028 (1948-1952) Fund's termination date the present value of the annuity payments the investor is entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund will be less the higher the prevailing interest rates. The Fund's adherence to the portfolio duration target formula is intended to result in the Fund having on its termination date net assets approximately equal to the present value of the aggregate annuity payments investors are entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund. However, even if a Fund successfully adheres to the formula, there is no guarantee that it will achieve this intended result or its investment objective. Although the Fund has no current plans to close, there is no guarantee that the Fund will continue to accept new investments until the termination date. As of the date of this Prospectus, based on the current U.S. Treasury Zero Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2028 (1948-1952) Fund's portfolio duration target would have been 22.3 years.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the 2028 (1948-1952) Fund. The following additional risks could affect the value of your investment: · Credit Risk. The issuers of the bonds and other debt securities held by the       2028 (1948-1952) Fund may not be able to make interest or principal payments      when due. Even if these issuers are able to make interest or principal            payments, changes in an issuer's credit rating or the market's perception of an   issuer's creditworthiness may also affect the value of the Fund's investment in   that issuer by leading to greater volatility in the price of the security.      · Credit Default Swap Risk. In a credit default swap transaction, both the 2028   (1948-1952) Fund and its counter-party are exposed to the risk of default by      the other. In addition, the terms of most credit default swap transactions        require little or no initial investment by the seller in relation to the          notional amount of the swap and the corresponding risk. Therefore, small          changes in the market value of the reference security or group of securities      may produce disproportionate and substantial losses for the seller.                · Derivatives Risk. Derivatives are securities, such as futures contracts, whose   value is derived from that of other securities or indices. The 2028 (1948-1952)   Fund's investments in derivatives may pose risks in addition to those             associated with investing directly in securities or other investments.            Derivative securities are subject to a number of risks including liquidity,       interest rate, market, credit and management risks, the risk of improper          valuation, illiquidity of the derivatives, imperfect correlations with            underlying investments or the Fund's other portfolio holdings, lack of            availability and counterparty risk. Changes in the value of the derivative may   not correlate perfectly with the underlying asset, rate or index, and the Fund   could lose more than the principal amount invested. An investment in              derivatives may not perform as anticipated by the Sub-Adviser, may not be able   to be closed out at a favorable time or price. An investment in derivatives may   also increase the Fund's volatility and create investment leverage. When a        derivative is used as a substitute or alternative to a direct cash investment,   the transaction may not provide a return that corresponds precisely with that     of the cash investment; or, when used for hedging purposes, derivatives may not   provide the anticipated protection, causing the Fund to lose money on both the   derivatives transaction and the exposure the Fund sought to hedge.              · Extension Risk. When interest rates rise, certain obligations will be paid off   by the obligor more slowly than anticipated, causing the value of these           securities to fall.                                                             · Foreign Investing Risk. The securities of foreign issuers may be less liquid      and more volatile than securities of comparable U.S. issuers. Investments in      securities of foreign issuers, even those publicly traded in the United States,   may involve risks which are in addition to those inherent in domestic             investments. Foreign companies may not be subject to the same regulatory          requirements of U.S. companies, and as a consequence, there may be less           publicly available information about such companies. Also, foreign companies      may not be subject to uniform accounting, auditing, and financial reporting       standards and requirements comparable to those applicable to U.S. companies.      Foreign governments and foreign economies often are less stable than the U.S.     Government and the U.S. economy.                                                   · Interest Rate Risk. In general, the value of bonds and other debt securities      falls when interest rates rise. Generally, the longer the duration of a debt      security, the greater is the negative effect on its value when rates              increase. Because zero coupon debt securities do not pay interest, the market     value of such securities can fall more dramatically than interest-paying          securities of similar maturities when interest rates rise. While bonds and        other debt securities normally fluctuate less in price than common stocks,        there have been extended periods of increases in interest rates that have         caused significant declines in bond prices.                                        · Management Risk. The 2028 (1948-1952) Fund is subject to management risk          because it is an actively managed portfolio. The portfolio manager's management   practices, investment strategies, and choice of investments might not work to     produce the desired results and the Fund might underperform other comparable      funds.                                                                             · Market Risk. The prices of the securities in which the 2028 (1948-1952) Fund      invests may decline for a number of reasons including in response to economic     developments and perceptions about the creditworthiness of individual             issuers. Longer-term bonds, in which the Fund will invest a majority of its       assets, are generally more volatile.                                               · New Fund Risk. The 2028 (1948-1952) Fund is new with no operating history and     there can be no assurance that the Fund will grow to or maintain an               economically viable size. If the Fund does not grow to or maintain an             economically viable size the Board may consider various alternatives, including   the liquidation of the Fund or the merger of the Fund into another mutual fund. · Portfolio Duration Target Formula Risk. There is no guarantee that adherence to   the portfolio duration target formula will result in the Fund achieving its       investment objective.                                                              · Prepayment Risk. When interest rates fall, certain obligations will be paid off   by the obligor more quickly than originally anticipated, and the 2028             (1948-1952) Fund may have to invest the proceeds in securities with lower         yields (this is known as Reinvestment Risk).                                    · Termination Risk. Because the 2028 (1948-1952) Fund has a Termination Date and   it will invest a majority of its assets in securities that mature after the       Termination Date, the Fund may incur liquidation costs to liquidate its           portfolio.                                                                         · U.S. Government Issuer Risk. Treasury obligations may differ in their interest   rates, maturities, times of issuance and other characteristics. Obligations of   U.S. Government agencies and authorities are supported by varying degrees of      credit but generally are not backed by the full faith and credit of the U.S.      Government. No assurance can be given that the U.S. Government will provide       financial support to its agencies and authorities if it is not obligated by law   to do so.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the 2028 (1948-1952) Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the 2028 (1948-1952) Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the 2028 (1948-1952) Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-SYMETRA (1-800-796-3872)
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra Pension Reserve Fund 2028 (b. 1948-1952) (Prospectus Summary) | Symetra Pension Reserve Fund 2028 (b. 1948-1952) | Symetra Pension Reserve Fund 2028 (b. 1948-1952)
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.32%
Other Expenses	rr_OtherExpensesOverAssets	1.77%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.09%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.69%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.40%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	41
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	491

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2028 (b.1948-1952) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra Pension Reserve Fund 2020 (b. 1948-1952) (Prospectus Summary) | Symetra Pension Reserve Fund 2020 (b. 1948-1952)
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra Pension Reserve Fund - 2020 (b.1948-1952)
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra Pension Reserve Fund - 2020 (b.1948-1952) (the "2020 (1948-1952) Fund" or the "Fund") seeks investment returns that would provide an amount on the Fund's termination date approximately equal to the then present value of specified lifetime annuity payments to be made to investors born in the year range identified in the Fund's name. As a result of its investment objective, a Pension Reserve Fund may not be a wise investment choice for an investor who does not anticipate applying his or her accumulation to the purchase of a lifetime annuity on or shortly after the Fund's termination date.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the 2020 (1948-1952) Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The 2020 (1948-1952) Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" is an estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the 2020 (1948-1952) Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The 2020 (1948-1952) Fund invests primarily in government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the three highest categories by an NRSRO or unrated securities that the Sub-Adviser determines are of comparable quality. The Fund also may invest in other types of dollar-denominated investment grade debt securities, including money market instruments and securities of foreign issuers. Most of the securities held by the Fund are zero coupon debt securities. Under normal market conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the two highest categories by an NRSRO, and investing in other permitted investments when government securities and corporate securities in the two highest categories are not available in sufficient quantities at a reasonable price or are not available in optimal durations or maturities.  The Fund also may manage portfolio duration by investing in interest rate futures contracts, options on interest rate futures contracts, structured notes and entering into swap agreements, provided that structured notes and swap agreements are determined by the Sub-Adviser to pose minimal counter-party credit risk. The 2020 (1948-1952) Fund is managed to continuously meet portfolio duration targets that correspond to projected payments, based on actuarially determined survivorship rates, of a single life annuity on the life of a person born in the year-range identified in the Fund's name. The portfolio duration targets are recalculated at least monthly based on a formula established by the Adviser (after consultation with Symetra Life Insurance Company ("Symetra Life")) at the Fund's inception. The formula will not change once the Fund commences operations. (The only variables in the formula are the amount of time remaining until each annual projected payment of the single life annuity and the prevailing interest rates on the recalculation date. The prevailing interest rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet the Fund's daily portfolio duration target by first, to the extent that such investments are available, investing in securities having cash flows similar to the projected payments of the single life annuity and then by balancing investments in securities with longer and shorter durations than the target duration. The portfolio duration target generally declines for the Fund over the life of the Fund, but will be substantially greater than zero at the Fund's termination date. As a result, to meet the portfolio duration target, the Fund will likely have an investment portfolio at its termination date of debt securities of substantial remaining duration. This in turn, will result in the market value of the Fund's investment portfolio at the termination date being significantly influenced by prevailing interest rates. Generally speaking, the higher the prevailing rates at the Fund's maturity, the less the Fund will receive from selling its assets and the lower the prevailing rates, the more the Fund will receive for selling its assets. Thus, the market value of such assets is inversely related to prevailing interest rates. The present value of a future series of payments decreases as the interest rate on which the present value is computed increases. Therefore, on the 2020 (1948-1952) Fund's termination date the present value of the annuity payments the investor is entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund will be less the higher the prevailing interest rates. The Fund's adherence to the portfolio duration target formula is intended to result in the Fund having on its termination date net assets approximately equal to the present value of the aggregate annuity payments investors are entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund. However, even if a Fund successfully adheres to the formula, there is no guarantee that it will achieve this intended result or its investment objective. Although the Fund has no current plans to close, there is no guarantee that the Fund will continue to accept new investments until the termination date. As of the date of this Prospectus, based on the current U.S. Treasury Zero Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2020 (1948-1952) Fund's portfolio duration target would have been 17.8 years.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the 2020 (1948-1952) Fund. The following additional risks could affect the value of your investment: · Credit Risk. The issuers of the bonds and other debt securities held by the       2020 (1948-1952) Fund may not be able to make interest or principal payments      when due. Even if these issuers are able to make interest or principal            payments, changes in an issuer's credit rating or the market's perception of an   issuer's creditworthiness may also affect the value of the Fund's investment in   that issuer by leading to greater volatility in the price of the security.      · Credit Default Swap Risk. In a credit default swap transaction, both the 2020   (1948-1952) Fund and its counter-party are exposed to the risk of default by      the other. In addition, the terms of most credit default swap transactions        require little or no initial investment by the seller in relation to the          notional amount of the swap and the corresponding risk. Therefore, small          changes in the market value of the reference security or group of securities      may produce disproportionate and substantial losses for the seller.                · Derivatives Risk. Derivatives are securities, such as futures contracts, whose   value is derived from that of other securities or indices. The 2020 (1948-1952)   Fund's investments in derivatives may pose risks in addition to those             associated with investing directly in securities or other investments.            Derivative securities are subject to a number of risks including liquidity,       interest rate, market, credit and management risks, the risk of improper          valuation, illiquidity of the derivatives, imperfect correlations with            underlying investments or the Fund's other portfolio holdings, lack of            availability and counterparty risk. Changes in the value of the derivative may   not correlate perfectly with the underlying asset, rate or index, and the Fund   could lose more than the principal amount invested. An investment in              derivatives may not perform as anticipated by the Sub-Adviser, may not be able   to be closed out at a favorable time or price. An investment in derivatives may   also increase the Fund's volatility and create investment leverage. When a        derivative is used as a substitute or alternative to a direct cash investment,   the transaction may not provide a return that corresponds precisely with that     of the cash investment; or, when used for hedging purposes, derivatives may not   provide the anticipated protection, causing the Fund to lose money on both the   derivatives transaction and the exposure the Fund sought to hedge.                 · Extension Risk. When interest rates rise, certain obligations will be paid off   by the obligor more slowly than anticipated, causing the value of these           securities to fall.                                                                · Foreign Investing Risk. The securities of foreign issuers may be less liquid      and more volatile than securities of comparable U.S. issuers. Investments in      securities of foreign issuers, even those publicly traded in the United States,   may involve risks which are in addition to those inherent in domestic             investments. Foreign companies may not be subject to the same regulatory          requirements of U.S. companies, and as a consequence, there may be less           publicly available information about such companies. Also, foreign companies      may not be subject to uniform accounting, auditing, and financial reporting       standards and requirements comparable to those applicable to U.S. companies.      Foreign governments and foreign economies often are less stable than the U.S.     Government and the U.S. economy.                                                · Interest Rate Risk. In general, the value of bonds and other debt securities      falls when interest rates rise. Generally, the longer the duration of a debt      security, the greater is the negative effect on its value when rates              increase. Because zero coupon debt securities do not pay interest, the market     value of such securities can fall more dramatically than interest-paying          securities of similar maturities when interest rates rise. While bonds and        other debt securities normally fluctuate less in price than common stocks,        there have been extended periods of increases in interest rates that have         caused significant declines in bond prices.                                        · Management Risk. The 2020 (1948-1952) Fund is subject to management risk          because it is an actively managed portfolio. The portfolio manager's management   practices, investment strategies, and choice of investments might not work to     produce the desired results and the Fund might underperform other comparable      funds.                                                                             · Market Risk. The prices of the securities in which the 2020 (1948-1952) Fund      invests may decline for a number of reasons including in response to economic     developments and perceptions about the creditworthiness of individual             issuers. Longer-term bonds, in which the Fund will invest a majority of its       assets, are generally more volatile.                                               · New Fund Risk. The 2020 (1948-1952) Fund is new with no operating history and     there can be no assurance that the Fund will grow to or maintain an               economically viable size. If the Fund does not grow to or maintain an             economically viable size the Board may consider various alternatives, including   the liquidation of the Fund or the merger of the Fund into another mutual fund. · Portfolio Duration Target Formula Risk. There is no guarantee that adherence to   the portfolio duration target formula will result in the Fund achieving its       investment objective.                                                           · Prepayment Risk. When interest rates fall, certain obligations will be paid off   by the obligor more quickly than originally anticipated, and the 2020             (1948-1952) Fund may have to invest the proceeds in securities with lower         yields (this is known as Reinvestment Risk).                                    · Termination Risk. Because the 2020 (1948-1952) Fund has a Termination Date and   it will invest a majority of its assets in securities that mature after the       Termination Date, the Fund may incur liquidation costs to liquidate its           portfolio.                                                                      · U.S. Government Issuer Risk. Treasury obligations may differ in their interest   rates, maturities, times of issuance and other characteristics. Obligations of   U.S. Government agencies and authorities are supported by varying degrees of      credit but generally are not backed by the full faith and credit of the U.S.      Government. No assurance can be given that the U.S. Government will provide       financial support to its agencies and authorities if it is not obligated by law   to do so.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the 2020 (1948-1952) Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the 2020 (1948-1952) Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the 2020 (1948-1952) Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-SYMETRA (1-800-796-3872)
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra Pension Reserve Fund 2020 (b. 1948-1952) (Prospectus Summary) | Symetra Pension Reserve Fund 2020 (b. 1948-1952) | Symetra Pension Reserve Fund 2020 (b. 1948-1952)
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.32%
Other Expenses	rr_OtherExpensesOverAssets	1.77%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.09%
Less: Fee Waiver and/or Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.69%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.40%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	41
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	491

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2020 (b.1948-1952) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra DoubleLine Total Return Fund (Prospectus Summary) | Symetra DoubleLine Total Return Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra DoubleLine® Total Return Fund
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra DoubleLine® Total Return Fund (the "Total Return Fund" or the "Fund") seeks total return through both income and capital appreciation.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the Total Return Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The Total Return Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" is an estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Total Return Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Total Return Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	Under normal market conditions, the Fund pursues its investment objective by investing at least 80% of its net assets (plus the amount of borrowings for investment purposes) in debt securities. Under normal market conditions, the Fund invests more than half of its assets in mortgage-backed government securities, mortgage-backed securities collateralized by government securities, and privately-issued high grade mortgage-backed securities, including inverse floaters. The Fund also may invest up to 35% of its assets in lower-rated bonds (commonly known as junk bonds), bank loans and assignments, and credit default swap agreements. Investment in secured or unsecured fixed or floating rate loans arranged through private negotiations between a borrower and one or more financial institutions may be in the form of participations in loans or assignments of all or a portion of loans from third parties. Under normal market conditions, the Fund generally seeks a target weighted average effective duration of one to eight years, though actual duration may vary considerably from this target. Portfolio securities may be sold at any time. Sales may occur when the Total Return Fund's portfolio managers determine to take advantage of a better investment opportunity because the portfolio managers believe the portfolio securities no longer represent relatively attractive investment opportunities, there is perceived deterioration in the credit fundamentals of the issuer or if they believe it would be appropriate to do so in order to readjust the duration of the Fund's investment portfolio.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the Total Return Fund. The following additional risks could affect the value of your investment: · Credit Risk. The issuers of the bonds and other debt securities held by the       Fund may not be able to make interest or principal payments when due. Even if     these issuers are able to make interest or principal payments, changes in an      issuer's credit rating or the market's perception of an issuer's                  creditworthiness may also affect the value of the Fund's investment in that       issuer by leading to greater volatility in the price of the security.              · Credit Default Swap Risk. In a credit default swap transaction, both the Fund   and its counter-party are exposed to the risk of default by the other. In         addition, the terms of most credit default swap transactions require little or   no initial investment by the seller in relation to the notional amount of the     swap and the corresponding risk. Therefore, small changes in the market value     of the reference security or group of securities may produce disproportionate     and substantial losses for the seller.                                          · Defaulted Securities Risk. There is a high level of uncertainty regarding the     repayment of defaulted securities and obligations of distressed issuers.        · Interest Rate Risk. In general, the value of bonds and other debt securities      falls when interest rates rise. Generally, the longer the duration of a debt      security, the greater is the negative effect on its value when rates              increase. While bonds and other debt securities normally fluctuate less in        price than common stocks, there have been extended periods of increases in        interest rates that have caused significant declines in bond prices.            · Junk Bond Risk. Although junk bonds generally pay higher rates of interest than   investment grade bonds, junk bonds are high risk investments that may cause       income and principal losses for the Total Return Fund. Junk bonds are subject     to reduced creditworthiness of issuers; increased risk of default and a more      limited and less liquid secondary market than higher rated securities; and        greater price volatility and risk of loss of income and principal than are        higher rated securities.                                                        · Leveraging Risk. Certain investments by the Total Return Fund may involve         leverage, which may have the effect of increasing the volatility of the Fund's   portfolio, and the risk of loss in excess of invested capital.                                                            · Liquidity Risk. In certain circumstances, low trading volume, lack of a market   maker, or contractual or legal restrictions may limit or prevent the Total        Return Fund from selling securities or closing any derivative positions within   a reasonable time at desirable prices. In addition, the ability of the Fund to   assign an accurate daily value to certain investments may be difficult, and the   Adviser may be required to fair value the investments.                          · Management Risk. The Total Return Fund is subject to management risk because it   is an actively managed portfolio. The portfolio managers' management practices,   investment strategies, and choice of investments might not work to produce the   desired results and the Fund might underperform other comparable funds.            · Market Risk. The prices of the securities in which the Total Return Fund          invests may decline for a number of reasons including in response to economic     or political developments and perceptions about the creditworthiness of           individual issuers or other issuer-specific events.                                · Mortgage-backed Securities Risk. Borrowers may default on their mortgage          obligations or the guarantees underlying the mortgage-backed securities may       default or otherwise fail and, during periods of falling interest rates,          mortgage-backed securities may be paid off by the obligor more quickly than       originally anticipated (this is known as Prepayment Risk), which may result in   the Total Return Fund having to reinvest proceeds in other investments at a       lower interest rate (this is also known as Reinvestment Risk). During periods     of rising interest rates, the average life of a mortgage-backed security may      extend, which may lock in a below-market interest rate, increase the security's   duration, and reduce the value of the security. Enforcing rights against the      underlying assets or collateral may be difficult, or the underlying assets or     collateral may be insufficient if the issuer defaults. The values of certain      types of mortgage-backed securities, such as inverse floaters and interest-only   and principal-only securities, may be extremely sensitive to changes in           interest rates and prepayment rates.                                               · New Fund Risk. The Total Return Fund is new with no operating history and there   can be no assurance that the Fund will grow to or maintain an economically        viable size. If the Fund does not grow to or maintain an economically viable      size, the Board may consider various alternatives, including the liquidation of   the Fund or the merger of the Fund into another mutual fund.                    · Real Estate Risk. Real estate-related investments may decline in value as a       result of factors affecting the real estate industry, such as the supply of       real property in certain markets, changes in zoning laws, delays in completion   of construction, changes in real estate values, changes in property taxes,        levels of occupancy, and local and regional market conditions.                     · U.S. Government Issuer Risk. Treasury obligations may differ in their interest   rates, maturities, times of issuance and other characteristics. Obligations of   U.S. Government agencies and authorities are supported by varying degrees of      credit but generally are not backed by the full faith and credit of the U.S.      Government. No assurance can be given that the U.S. Government will provide       financial support to its agencies and authorities if it is not obligated by law   to do so.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the Total Return Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the Total Return Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the Total Return Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-SYMETRA (1-800-796-3872)
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra DoubleLine Total Return Fund (Prospectus Summary) | Symetra DoubleLine Total Return Fund | Symetra DoubleLine Total Return Fund
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.55%
Other Expenses	rr_OtherExpensesOverAssets	2.10%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.65%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(2.02%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.63%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	64
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	631

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Total Return Fund (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Symetra Yacktman Focused Fund (Prospectus Summary) | Symetra Yacktman Focused Fund

Symetra Yacktman Focused Fund

Investment Objective

The Symetra Yacktman Focused Fund ("Focused Fund" or the "Fund") seeks long-term
capital appreciation and, to a lesser extent, income.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the Focused Fund. The expenses shown in the table and in the example
that follow do not reflect additional fees and expenses that will be applied at
the variable annuity or variable life insurance contract level. If those
additional fees and expenses were included, overall expenses would be higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra Yacktman Focused Fund
Management Fees		1.00%
Other Expenses	[1]	1.47%
Total Annual Fund Operating Expenses		2.47%
Less: Fee Waiver and Expense Reimbursement	[2]	(1.40%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		1.07%

Example

This Example is intended to help you compare the cost of investing in the
Focused Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated
and then redeem all of your shares at the end of those periods. The Example
also assumes that your investment has a 5% return each year and that the
Fund's operating expenses remain the same (taking into account the Expense
Cap and Fee Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra Yacktman Focused Fund	109	636

Portfolio Turnover

The Focused Fund pays transaction costs, such as commissions, when it buys and
sells securities (or "turns over" its portfolio). A higher portfolio turnover
rate may indicate higher transaction costs and may result in higher taxes when
Fund shares are held in a taxable account. These costs, which are not reflected
in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Fund

Under normal market conditions, the Focused Fund pursues its investment
objective by investing a majority of its assets in common stock of U.S. issuers.
Some, but not all, Fund holdings may pay dividends. The Sub-Adviser seeks to
purchase "growth" oriented issuers at low prices relative to value. Through this
approach, it attempts to combine the best features of "growth" and "value"
investing. The Fund is a non-diversified fund and generally will hold securities
of fewer issuers than the typical equity mutual fund. Consistent with this,
although the Fund invests in issuers of any size market capitalization, the
Sub-Adviser prefers larger companies to smaller ones.
  
The Focused Fund may invest up to 20% of its assets in equity securities of
foreign issuers. This 20% limit does not apply to investments in the form of
American Depositary Receipts ("ADRs"). The Fund may also invest up to 20% of its
assets in debt securities, including lower-rated securities (commonly referred
to as junk bonds). The Fund does not seek to align itself with any benchmark,
but rather is opportunistic in seeking attractively-priced securities that
represent predictable, quality investments, while protecting capital. As a
result, the Fund may experience periods when it is very selective about
investments and hold more cash than other equity mutual funds. Consistent with
this, the Fund may underperform its peers in strong equity markets and
outperform them in weaker markets.

The Sub-Adviser generally looks for issuers with one or more of the following
characteristics: (1) sound business prospects, (2) shareholder-oriented
management, and (3) securities with a low purchase price. In the Sub-Adviser's
view:

·   Companies with sound business prospects exhibit one or more of the following
    characteristics: (a) high market share in principal product/service lines,   
    (b) high cash return on tangible assets, (c) relatively low capital          
    requirements resulting in cash flow during growth periods, (d) long product  
    cycles combined with short customer purchase cycles, and (e) unique franchise
    characteristics.                                                             

·   Companies with shareholder oriented management exhibit one or more of the    
    following characteristics: (a) reinvest in the business yet generate excess  
    cash, (b) make synergistic acquisitions, and (c) purchase their own stock    
    when its price is low.                                                       
                                                                                 
·   A company has an attractively low stock price if the price has either of the
    following characteristics: (a) the market capitalization is less than what   
    the Sub-Adviser would pay for the entire company, or (b) the price is        
    volatile and not correlated with changes in the company's fundamental        
    performance.                                                                 

The Focused Fund sells companies that no longer meet its investment criteria, or
if better investment opportunities are available.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the Focused
Fund. The following additional risks could affect the value of your investment:

·   Credit Risk. The issuers of the bonds and other debt securities held by the  
    Focused Fund may not be able to make interest or principal payments when     
    due. Even if these issuers are able to make interest or principal payments,  
    changes in an issuer's credit rating or the market's perception of an        
    issuer's creditworthiness may also affect the value of the Fund's investment
    in that issuer by leading to greater volatility in the price of the security.

·   Interest Rate Risk. In general, the value of bonds and other debt securities
    falls when interest rates rise. Generally, the longer the duration of a debt
    security, the greater is the negative effect on its value when rates         
    increase. While bonds and other debt securities normally fluctuate less in   
    price than common stocks, there have been extended periods of increases in   
    interest rates that have caused significant declines in bond prices.         

·   Foreign Investing Risk. The securities of foreign issuers may be less liquid
    and more volatile than securities of comparable U.S. issuers. The costs      
    associated with securities transactions are often higher in foreign countries
    than the U.S. The U.S. dollar value of securities of foreign issuers traded  
    in foreign currencies (and any dividends and interest earned) held by the    
    Focused Fund may be affected favorably or unfavorably by changes in foreign  
    currency exchange rates. An increase in the U.S. dollar relative to these    
    other currencies will adversely affect the Fund (this is known as Foreign    
    Currency Risk). The Fund does not hedge foreign currency risk. Additionally,
    investments in securities of foreign issuers, even those publicly traded in  
    the United States, may involve risks which are in addition to those inherent
    in domestic investments. Foreign companies may not be subject to the same    
    regulatory requirements of U.S. companies, and as a consequence, there may be
    less publicly available information about such companies. Also, foreign      
    companies may not be subject to uniform accounting, auditing, and financial  
    reporting standards and requirements comparable to those applicable to U.S.  
    companies. Foreign governments and foreign economies often are less stable   
    than the U.S. Government and the U.S. economy.                               
  
·   Junk Bond Risk. Although junk bonds generally pay higher rates of interest   
    than investment grade bonds, junk bonds are high risk investments that may   
    cause income and principal losses for the Focused Fund. Junk bonds are       
    subject to reduced creditworthiness of issuers; increased risk of default and
    a more limited and less liquid secondary market than higher rated securities;
    and greater price volatility and risk of loss of income and principal than   
    are higher rated securities.                                                 

·   Management Risk. The Focused Fund is subject to management risk because it is
    an actively managed portfolio. The portfolio managers' management practices,
    investment strategies, and choice of investments might not work to produce   
    the desired results and the Fund might underperform other comparable funds.  

·   Market Risk. The prices of the securities in which the Fund invests may      
    decline for a number of reasons including in response to economic or         
    political developments and perceptions about the creditworthiness of         
    individual issuers or other issuer-specific events. The price declines of    
    common stocks, in particular, may be steep, sudden and/or prolonged.         

·   New Fund Risk. The Focused Fund is new with no operating history and there   
    can be no assurance that the Fund will grow to or maintain an economically   
    viable size. If the Fund does not grow to or maintain an economically viable
    size, the Board may consider various alternatives, including the liquidation
    of the Fund or the merger of the Fund into another mutual fund.              

·   Non-Diversification Risk. The Focused Fund is a non-diversified investment   
    company. As such, it will likely invest in fewer securities than diversified
    investment companies and its performance may be more volatile. The Fund may  
    be more susceptible to any single economic, political or regulatory event    
    than a more diversified fund. If the securities in which the Fund invests    
    perform poorly, the Fund could incur greater losses than it would have had it
    invested in a greater number of securities.                                  

·   Smaller Capitalization Companies Risk. Smaller capitalization companies      
    typically have relatively lower revenues, limited product lines and lack of  
    management depth, and may have a smaller share of the market for their       
    products or services, than larger capitalization companies. In general,      
    smaller capitalization companies are also more vulnerable than larger        
    companies to adverse business or economic developments. The stocks of smaller
    capitalization companies tend to be less liquid and have less trading volume
    than stocks of larger capitalization companies and this could make it        
    difficult to sell securities of smaller capitalization companies at a desired
    time or price. As a result, small company stocks may fluctuate relatively    
    more in price. Finally, there are periods when investing in smaller          
    capitalization stocks falls out of favor with investors and the stocks of    
    smaller-capitalization companies underperform.                               

·   Value Investing Risk. Value stocks may perform differently from the market as
    a whole and following a value-oriented investment strategy may cause the     
    Focused Fund to at times underperform equity funds that use other investment
    strategies.

Performance

When the Focused Fund has been in operation for a full calendar year, performance
information will be shown here. Updated performance information is available on the
Fund's website at www.symetra.com/funds or by calling the Fund toll-free at
1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.12% of the average daily net assets of the Focused Fund (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Symetra Pension Reserve Fund 2024 (b. 1953-1957) (Prospectus Summary) | Symetra Pension Reserve Fund 2024 (b. 1953-1957)

Symetra Pension Reserve Fund - 2024 (b.1953-1957)

Investment Objective

The Symetra Pension Reserve Fund - 2024 (b.1953-1957) (the "2024 (1953-1957)
Fund" or the "Fund") seeks investment returns that would provide an amount on
the Fund's termination date approximately equal to the then present value of
specified lifetime annuity payments to be made to investors born in the year
range identified in the Fund's name. As a result of its investment objective,
a Pension Reserve Fund may not be a wise investment choice for an investor who
does not anticipate applying his or her accumulation to the purchase of a
lifetime annuity on or shortly after the Fund's termination date.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the 2024 (1953-1957) Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity or variable life insurance contract level. If
those additional fees and expenses were included, overall expenses would be
higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra Pension Reserve Fund 2024 (b. 1953-1957)
Management Fees		0.32%
Other Expenses	[1]	1.77%
Total Annual Fund Operating Expenses		2.09%
Less: Fee Waiver and Expense Reimbursement	[2]	(1.69%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.40%

Example

This Example is intended to help you compare the cost of investing in the 2024
(1953-1957) Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated and
then redeem all of your shares at the end of those periods. The Example also
assumes that your investment has a 5% return each year and that the Fund's
operating expenses remain the same (taking into account the Expense Cap and Fee
Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra Pension Reserve Fund 2024 (b. 1953-1957)	41	491

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells
securities (or "turns over" its portfolio). A higher portfolio turnover rate
may indicate higher transaction costs and may result in higher taxes when Fund
shares are held in a taxable account. These costs, which are not reflected in
annual fund operating expenses or in the Example, affect the Fund's performance.
No portfolio turnover rate is presented for the Fund because it had not
commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Fund

The 2024 (1953-1957) Fund invests primarily in government securities and
dollar-denominated corporate debt securities rated, at the time of purchase,
in the three highest categories by an NRSRO or unrated securities that the
Sub-Adviser determines are of comparable quality. The Fund also may invest in
other types of dollar-denominated investment grade debt securities, including
money market instruments and securities of foreign issuers. Most of the
securities held by the Fund are zero coupon debt securities. Under normal market
conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring
government securities and dollar-denominated corporate debt securities rated, at
the time of purchase, in the two highest categories by an NRSRO, and investing
in other permitted investments when government securities and corporate
securities in the two highest categories are not available in sufficient
quantities at a reasonable price or are not available in optimal durations or
maturities.  The Fund also may manage portfolio duration by investing in
interest rate futures contracts, options on interest rate futures contracts,
structured notes and entering into swap agreements, provided that structured
notes and swap agreements are determined by the Sub-Adviser to pose minimal
counter-party credit risk.

The 2024 (1953-1957) Fund is managed to continuously meet portfolio duration
targets that correspond to projected payments, based on actuarially determined
survivorship rates, of a single life annuity on the life of a person born in the
year-range identified in the Fund's name. The portfolio duration targets are
recalculated at least monthly based on a formula established by the Adviser
(after consultation with Symetra Life Insurance Company ("Symetra Life")) at the
Fund's inception. The formula will not change once the Fund commences operations.
(The only variables in the formula are the amount of time remaining until each
annual projected payment of the single life annuity and the prevailing interest
rates on the recalculation date. The prevailing interest rates are derived from
the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under
normal market conditions, the Sub-Adviser seeks to meet the Fund's daily
portfolio duration target by first, to the extent that such investments are
available, investing in securities having cash flows similar to the projected
payments of the single life annuity and then by balancing investments in
securities with longer and shorter durations than the target duration. The
portfolio duration target generally declines for the Fund over the life of the
Fund, but will be substantially greater than zero at the Fund's termination
date. As a result, to meet the portfolio duration target, the Fund will likely
have an investment portfolio at its termination date of debt securities of
substantial remaining duration. This in turn, will result in the market value
of the Fund's investment portfolio at the termination date being significantly
influenced by prevailing interest rates. Generally speaking, the higher the
prevailing rates at the Fund's maturity, the less the Fund will receive from
selling its assets and the lower the prevailing rates, the more the Fund will
receive for selling its assets. Thus, the market value of such assets is
inversely related to prevailing interest rates.

The present value of a future series of payments decreases as the interest rate
on which the present value is computed increases. Therefore, on the 2024
(1953-1957) Fund's termination date the present value of the annuity payments
the investor is entitled to receive as a result of owning accumulation units in
the sub-account of the Symetra Resource Variable Account B that invests in
shares of the Fund will be less the higher the prevailing interest rates. The
Fund's adherence to the portfolio duration target formula is intended to result
in the Fund having on its termination date net assets approximately equal to the
present value of the aggregate annuity payments investors are entitled to
receive as a result of owning accumulation units in the sub-account of the
Symetra Resource Variable Account B that invests in shares of the Fund. However,
even if a Fund successfully adheres to the formula, there is no guarantee that
it will achieve this intended result or its investment objective. Although the
Fund has no current plans to close, there is no guarantee that the Fund will
continue to accept new investments until the termination date.

As of the date of this Prospectus, based on the current U.S. Treasury Zero
Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2024
(1953-1957) Fund's portfolio duration target would have been 21.7 years.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the 2024
(1953-1957) Fund. The following additional risks could affect the value of your
investment:

· Credit Risk. The issuers of the bonds and other debt securities held by the    
  2024 (1953-1957) Fund may not be able to make interest or principal payments   
  when due. Even if these issuers are able to make interest or principal         
  payments, changes in an issuer's credit rating or the market's perception of an
  issuer's creditworthiness may also affect the value of the Fund's investment in
  that issuer by leading to greater volatility in the price of the security.     
  
· Credit Default Swap Risk. In a credit default swap transaction, both the 2024
  (1953-1957) Fund and its counter-party are exposed to the risk of default by   
  the other. In addition, the terms of most credit default swap transactions     
  require little or no initial investment by the seller in relation to the       
  notional amount of the swap and the corresponding risk. Therefore, small       
  changes in the market value of the reference security or group of securities   
  may produce disproportionate and substantial losses for the seller.            

· Derivatives Risk. Derivatives are securities, such as futures contracts, whose
  value is derived from that of other securities or indices. The 2024 (1953-1957)
  Fund's investments in derivatives may pose risks in addition to those          
  associated with investing directly in securities or other investments.         
  Derivative securities are subject to a number of risks including liquidity,    
  interest rate, market, credit and management risks, the risk of improper       
  valuation, illiquidity of the derivatives, imperfect correlations with         
  underlying investments or the Fund's other portfolio holdings, lack of         
  availability and counterparty risk. Changes in the value of the derivative may
  not correlate perfectly with the underlying asset, rate or index, and the Fund
  could lose more than the principal amount invested. An investment in           
  derivatives may not perform as anticipated by the Sub-Adviser, may not be able
  to be closed out at a favorable time or price. An investment in derivatives may
  also increase the Fund's volatility and create investment leverage. When a     
  derivative is used as a substitute or alternative to a direct cash investment,
  the transaction may not provide a return that corresponds precisely with that  
  of the cash investment; or, when used for hedging purposes, derivatives may not
  provide the anticipated protection, causing the Fund to lose money on both the
  derivatives transaction and the exposure the Fund sought to hedge.             

· Extension Risk. When interest rates rise, certain obligations will be paid off
  by the obligor more slowly than anticipated, causing the value of these        
  securities to fall.                                                            

· Foreign Investing Risk. The securities of foreign issuers may be less liquid   
  and more volatile than securities of comparable U.S. issuers. Investments in   
  securities of foreign issuers, even those publicly traded in the United States,
  may involve risks which are in addition to those inherent in domestic          
  investments. Foreign companies may not be subject to the same regulatory       
  requirements of U.S. companies, and as a consequence, there may be less        
  publicly available information about such companies. Also, foreign companies   
  may not be subject to uniform accounting, auditing, and financial reporting    
  standards and requirements comparable to those applicable to U.S. companies.   
  Foreign governments and foreign economies often are less stable than the U.S.  
  Government and the U.S. economy.                                               

· Interest Rate Risk. In general, the value of bonds and other debt securities   
  falls when interest rates rise. Generally, the longer the duration of a debt   
  security, the greater is the negative effect on its value when rates           
  increase. Because zero coupon debt securities do not pay interest, the market  
  value of such securities can fall more dramatically than interest-paying       
  securities of similar maturities when interest rates rise. While bonds and     
  other debt securities normally fluctuate less in price than common stocks,     
  there have been extended periods of increases in interest rates that have      
  caused significant declines in bond prices.                                    

· Management Risk. The 2024 (1953-1957) Fund is subject to management risk       
  because it is an actively managed portfolio. The portfolio manager's management
  practices, investment strategies, and choice of investments might not work to  
  produce the desired results and the Fund might underperform other comparable   
  funds.                                                                         

· Market Risk. The prices of the securities in which the 2024 (1953-1957) Fund   
  invests may decline for a number of reasons including in response to economic  
  developments and perceptions about the creditworthiness of individual          
  issuers. Longer-term bonds, in which the Fund will invest a majority of its    
  assets, are generally more volatile.                                           

· New Fund Risk. The 2024 (1953-1957) Fund is new with no operating history and  
  there can be no assurance that the Fund will grow to or maintain an            
  economically viable size. If the Fund does not grow to or maintain an          
  economically viable size the Board may consider various alternatives, including
  the liquidation of the Fund or the merger of the Fund into another mutual fund.
  
· Portfolio Duration Target Formula Risk. There is no guarantee that adherence to
  the portfolio duration target formula will result in the Fund achieving its    
  investment objective.                                                          

· Prepayment Risk. When interest rates fall, certain obligations will be paid off
  by the obligor more quickly than originally anticipated, and the 2024          
  (1953-1957) Fund may have to invest the proceeds in securities with lower      
  yields (this is known as Reinvestment Risk).                                   

· Termination Risk. Because the 2024 (1953-1957) Fund has a Termination Date and
  it will invest a majority of its assets in securities that mature after the    
  Termination Date, the Fund may incur liquidation costs to liquidate its        
  portfolio.                                                                     

· U.S. Government Issuer Risk. Treasury obligations may differ in their interest
  rates, maturities, times of issuance and other characteristics. Obligations of
  U.S. Government agencies and authorities are supported by varying degrees of   
  credit but generally are not backed by the full faith and credit of the U.S.   
  Government. No assurance can be given that the U.S. Government will provide    
  financial support to its agencies and authorities if it is not obligated by law
  to do so.

Performance

When the 2024 (1953-1957) Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2024 (b.1953-1957) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	May 18, 2012
Symetra Pension Reserve Fund 2020 (b. 1958-1962) (Prospectus Summary) | Symetra Pension Reserve Fund 2020 (b. 1958-1962)
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	Symetra Pension Reserve Fund - 2020 (b.1958-1962)
Investment Objective, Heading	rr_ObjectiveHeading	Investment Objective
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	The Symetra Pension Reserve Fund - 2020 (b.1958-1962) (the "2020 (1958-1962) Fund" or the "Fund") seeks investment returns that would provide an amount on the Fund's termination date approximately equal to the then present value of specified lifetime annuity payments to be made to investors born in the year range identified in the Fund's name. As a result of its investment objective, a Pension Reserve Fund may not be a wise investment choice for an investor who does not anticipate applying his or her accumulation to the purchase of a lifetime annuity on or shortly after the Fund's termination date.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of the 2020 (1958-1962) Fund. The expenses shown in the table and in the example that follow do not reflect additional fees and expenses that will be applied at the variable annuity or variable life insurance contract level. If those additional fees and expenses were included, overall expenses would be higher.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment) N/A
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The 2020 (1958-1962) Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund's performance. No portfolio turnover rate is presented for the Fund because it had not commenced operations as of the date of this Prospectus.
Other Expenses, New Fund, Based on Estimates	rr_OtherExpensesNewFundBasedOnEstimates	"Other expenses" is an estimated amount for the current fiscal year.
Expense Example, Heading	rr_ExpenseExampleHeading	Example
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the 2020 (1958-1962) Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same (taking into account the Expense Cap and Fee Waiver only in the first year).
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions, your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies of the Fund
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	The 2020 (1958-1962) Fund invests primarily in government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the three highest categories by an NRSRO or unrated securities that the Sub-Adviser determines are of comparable quality. The Fund also may invest in other types of dollar-denominated investment grade debt securities, including money market instruments and securities of foreign issuers. Most of the securities held by the Fund are zero coupon debt securities. Under normal market conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring government securities and dollar-denominated corporate debt securities rated, at the time of purchase, in the two highest categories by an NRSRO, and investing in other permitted investments when government securities and corporate securities in the two highest categories are not available in sufficient quantities at a reasonable price or are not available in optimal durations or maturities.  The Fund also may manage portfolio duration by investing in interest rate futures contracts, options on interest rate futures contracts, structured notes and entering into swap agreements, provided that structured notes and swap agreements are determined by the Sub-Adviser to pose minimal counter-party credit risk. The 2020 (1958-1962) Fund is managed to continuously meet portfolio duration targets that correspond to projected payments, based on actuarially determined survivorship rates, of a single life annuity on the life of a person born in the year-range identified in the Fund's name. The portfolio duration targets are recalculated at least monthly based on a formula established by the Adviser (after consultation with Symetra Life Insurance Company ("Symetra Life")) at the Fund's inception. The formula will not change once the Fund commences operations. (The only variables in the formula are the amount of time remaining until each annual projected payment of the single life annuity and the prevailing interest rates on the recalculation date. The prevailing interest rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet the Fund's daily portfolio duration target by first, to the extent that such investments are available, investing in securities having cash flows similar to the projected payments of the single life annuity and then by balancing investments in securities with longer and shorter durations than the target duration. The portfolio duration target generally declines for the Fund over the life of the Fund, but will be substantially greater than zero at the Fund's termination date. As a result, to meet the portfolio duration target, the Fund will likely have an investment portfolio at its termination date of debt securities of substantial remaining duration. This in turn, will result in the market value of the Fund's investment portfolio at the termination date being significantly influenced by prevailing interest rates. Generally speaking, the higher the prevailing rates at the Fund's maturity, the less the Fund will receive from selling its assets and the lower the prevailing rates, the more the Fund will receive for selling its assets. Thus, the market value of such assets is inversely related to prevailing interest rates. The present value of a future series of payments decreases as the interest rate on which the present value is computed increases. Therefore, on the 2020 (1958-1962) Fund's termination date the present value of the annuity payments the investor is entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund will be less the higher the prevailing interest rates. The Fund's adherence to the portfolio duration target formula is intended to result in the Fund having on its termination date net assets approximately equal to the present value of the aggregate annuity payments investors are entitled to receive as a result of owning accumulation units in the sub-account of the Symetra Resource Variable Account B that invests in shares of the Fund. However, even if a Fund successfully adheres to the formula, there is no guarantee that it will achieve this intended result or its investment objective. Although the Fund has no current plans to close, there is no guarantee that the Fund will continue to accept new investments until the termination date. As of the date of this Prospectus, based on the current U.S. Treasury Zero Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2020 (1958-1962) Fund's portfolio duration target would have been 21.1 years.
Risk, Heading	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk, Narrative	rr_RiskNarrativeTextBlock	Losing all or a portion of your investment is a risk of investing in the 2020 (1958-1962) Fund. The following additional risks could affect the value of your investment: · Credit Risk. The issuers of the bonds and other debt securities held by the       2020 (1958-1962) Fund may not be able to make interest or principal payments      when due. Even if these issuers are able to make interest or principal            payments, changes in an issuer's credit rating or the market's perception of an   issuer's creditworthiness may also affect the value of the Fund's investment in   that issuer by leading to greater volatility in the price of the security.         · Credit Default Swap Risk. In a credit default swap transaction, both the 2020   (1958-1962) Fund and its counter-party are exposed to the risk of default by      the other. In addition, the terms of most credit default swap transactions        require little or no initial investment by the seller in relation to the          notional amount of the swap and the corresponding risk. Therefore, small          changes in the market value of the reference security or group of securities      may produce disproportionate and substantial losses for the seller.             · Derivatives Risk. Derivatives are securities, such as futures contracts, whose   value is derived from that of other securities or indices. The 2020 (1958-1962)   Fund's investments in derivatives may pose risks in addition to those             associated with investing directly in securities or other investments.            Derivative securities are subject to a number of risks including liquidity,       interest rate, market, credit and management risks, the risk of improper          valuation, illiquidity of the derivatives, imperfect correlations with            underlying investments or the Fund's other portfolio holdings, lack of            availability and counterparty risk. Changes in the value of the derivative may   not correlate perfectly with the underlying asset, rate or index, and the Fund   could lose more than the principal amount invested. An investment in              derivatives may not perform as anticipated by the Sub-Adviser, may not be able   to be closed out at a favorable time or price. An investment in derivatives may   also increase the Fund's volatility and create investment leverage. When a        derivative is used as a substitute or alternative to a direct cash investment,   the transaction may not provide a return that corresponds precisely with that     of the cash investment; or, when used for hedging purposes, derivatives may not   provide the anticipated protection, causing the Fund to lose money on both the   derivatives transaction and the exposure the Fund sought to hedge.              · Extension Risk. When interest rates rise, certain obligations will be paid off   by the obligor more slowly than anticipated, causing the value of these           securities to fall.                                                             · Foreign Investing Risk. The securities of foreign issuers may be less liquid      and more volatile than securities of comparable U.S. issuers. Investments in      securities of foreign issuers, even those publicly traded in the United States,   may involve risks which are in addition to those inherent in domestic             investments. Foreign companies may not be subject to the same regulatory          requirements of U.S. companies, and as a consequence, there may be less           publicly available information about such companies. Also, foreign companies      may not be subject to uniform accounting, auditing, and financial reporting       standards and requirements comparable to those applicable to U.S. companies.      Foreign governments and foreign economies often are less stable than the U.S.     Government and the U.S. economy.                                                · Interest Rate Risk. In general, the value of bonds and other debt securities      falls when interest rates rise. Generally, the longer the duration of a debt      security, the greater is the negative effect on its value when rates              increase. Because zero coupon debt securities do not pay interest, the market     value of such securities can fall more dramatically than interest-paying          securities of similar maturities when interest rates rise. While bonds and        other debt securities normally fluctuate less in price than common stocks,        there have been extended periods of increases in interest rates that have         caused significant declines in bond prices.                                     · Management Risk. The 2020 (1958-1962) Fund is subject to management risk          because it is an actively managed portfolio. The portfolio manager's management   practices, investment strategies, and choice of investments might not work to     produce the desired results and the Fund might underperform other comparable      funds.                                                                          · Market Risk. The prices of the securities in which the 2020 (1958-1962) Fund      invests may decline for a number of reasons including in response to economic     developments and perceptions about the creditworthiness of individual             issuers. Longer-term bonds, in which the Fund will invest a majority of its       assets, are generally more volatile.                                            · New Fund Risk. The 2020 (1958-1962) Fund is new with no operating history and     there can be no assurance that the Fund will grow to or maintain an               economically viable size. If the Fund does not grow to or maintain an             economically viable size the Board may consider various alternatives, including   the liquidation of the Fund or the merger of the Fund into another mutual fund.    · Portfolio Duration Target Formula Risk. There is no guarantee that adherence to   the portfolio duration target formula will result in the Fund achieving its       investment objective.                                                           · Prepayment Risk. When interest rates fall, certain obligations will be paid off   by the obligor more quickly than originally anticipated, and the 2020             (1958-1962) Fund may have to invest the proceeds in securities with lower         yields (this is known as Reinvestment Risk).                                    · Termination Risk. Because the 2020 (1958-1962) Fund has a Termination Date and   it will invest a majority of its assets in securities that mature after the       Termination Date, the Fund may incur liquidation costs to liquidate its           portfolio.                                                                      · U.S. Government Issuer Risk. Treasury obligations may differ in their interest   rates, maturities, times of issuance and other characteristics. Obligations of   U.S. Government agencies and authorities are supported by varying degrees of      credit but generally are not backed by the full faith and credit of the U.S.      Government. No assurance can be given that the U.S. Government will provide       financial support to its agencies and authorities if it is not obligated by law   to do so.
Risk, Lose Money	rr_RiskLoseMoney	Losing all or a portion of your investment is a risk of investing in the 2020 (1958-1962) Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance
Performance, Narrative	rr_PerformanceNarrativeTextBlock	When the 2020 (1958-1962) Fund has been in operation for a full calendar year, performance information will be shown here. Updated performance information is available on the Fund's website at www.symetra.com/funds or by calling the Fund toll-free at 1-800-SYMETRA (1-800-796-3872).
Performance, One Year or Less	rr_PerformanceOneYearOrLess	When the 2020 (1958-1962) Fund has been in operation for a full calendar year, performance information will be shown here.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-SYMETRA (1-800-796-3872)
Performance, Availability Website Address	rr_PerformanceAvailabilityWebSiteAddress	www.symetra.com/funds
Symetra Pension Reserve Fund 2020 (b. 1958-1962) (Prospectus Summary) | Symetra Pension Reserve Fund 2020 (b. 1958-1962) | Symetra Pension Reserve Fund 2020 (b. 1958-1962)
Risk Return [Abstract]	rr_RiskReturnAbstract
Management Fees	rr_ManagementFeesOverAssets	0.32%
Other Expenses	rr_OtherExpensesOverAssets	1.77%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.09%
Less: Fee Waiver and Expense Reimbursement	rr_FeeWaiverOrReimbursementOverAssets	(1.69%)	[2]
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement	rr_NetExpensesOverAssets	0.40%
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	2013-04-30
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	41
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	491

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2020 (b.1958-1962) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Symetra Pension Reserve Fund 2028 (b. 1958-1962) (Prospectus Summary) | Symetra Pension Reserve Fund 2028 (b. 1958-1962)

Symetra Pension Reserve Fund - 2028 (b.1958-1962)

Investment Objective

The Symetra Pension Reserve Fund - 2028 (b.1958-1962) (the "2028 (1958-1962)
Fund" or the "Fund") seeks investment returns that would provide an amount on
the Fund's termination date approximately equal to the then present value of
specified lifetime annuity payments to be made to investors born in the year
range identified in the Fund's name. As a result of its investment objective,
a Pension Reserve Fund may not be a wise investment choice for an investor
who does not anticipate applying his or her accumulation to the purchase of a
lifetime annuity on or shortly after the Fund's termination date.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the 2028 (1958-1962) Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity or variable life insurance contract level. If
those additional fees and expenses were included, overall expenses would be
higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra Pension Reserve Fund 2028 (b. 1958-1962)
Management Fees		0.32%
Other Expenses	[1]	1.77%
Total Annual Fund Operating Expenses		2.09%
Less: Fee Waiver and Expense Reimbursement	[2]	(1.69%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.40%

Example

This Example is intended to help you compare the cost of investing in the 2028
(1958-1962) Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated and
then redeem all of your shares at the end of those periods. The Example also
assumes that your investment has a 5% return each year and that the Fund's
operating expenses remain the same (taking into account the Expense Cap and Fee
Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra Pension Reserve Fund 2028 (b. 1958-1962)	41	491

Portfolio Turnover

The 2028 (1958-1962) Fund pays transaction costs, such as commissions, when it
buys and sells securities (or "turns over" its portfolio). A higher portfolio
turnover rate may indicate higher transaction costs and may result in higher
taxes when Fund shares are held in a taxable account. These costs, which are not
reflected in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Fund

The 2028 (1958-1962) Fund invests primarily in government securities and
dollar-denominated corporate debt securities rated, at the time of purchase, in
the three highest categories by an NRSRO or unrated securities that the
Sub-Adviser determines are of comparable quality. The Fund also may invest in
other types of dollar-denominated investment grade debt securities, including
money market instruments and securities of foreign issuers. Most of the
securities held by the Fund are zero coupon debt securities. Under normal market
conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring
government securities and dollar-denominated corporate debt securities rated, at
the time of purchase, in the two highest categories by an NRSRO, and investing
in other permitted investments when government securities and corporate
securities in the two highest categories are not available in sufficient
quantities at a reasonable price or are not available in optimal durations or
maturities.  The Fund also may manage portfolio duration by investing in
interest rate futures contracts, options on interest rate futures contracts,
structured notes and entering into swap agreements, provided that structured
notes and swap agreements are determined by the Sub-Adviser to pose minimal
counter-party credit risk.

The 2028 (1958-1962) Fund is managed to continuously meet portfolio duration
targets that correspond to projected payments, based on actuarially determined
survivorship rates, of a single life annuity on the life of a person born in the
year-range identified in the Fund's name. The portfolio duration targets are
recalculated at least monthly based on a formula established by the Adviser
(after consultation with Symetra Life Insurance Company ("Symetra Life")) at the
Fund's inception. The formula will not change once the Fund commences
operations. (The only variables in the formula are the amount of time remaining
until each annual projected payment of the single life annuity and the
prevailing interest rates on the recalculation date. The prevailing interest
rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by
interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet
the Fund's daily portfolio duration target by first, to the extent that such
investments are available, investing in securities having cash flows similar to
the projected payments of the single life annuity and then by balancing
investments in securities with longer and shorter durations than the target
duration. The portfolio duration target generally declines for the Fund over the
life of the Fund, but will be substantially greater than zero at the Fund's
termination date. As a result, to meet the portfolio duration target, the Fund
will have an investment portfolio at its termination date of debt securities of
substantial remaining duration. This in turn, will likely result in the market
value of the Fund's investment portfolio at the termination date being
significantly influenced by prevailing interest rates. Generally speaking, the
higher the prevailing rates at the Fund's maturity, the less the Fund will
receive from selling its assets and the lower the prevailing rates, the more the
Fund will receive for selling its assets. Thus, the market value of such assets
is inversely related to prevailing interest rates.

The present value of a future series of payments decreases as the interest rate
on which the present value is computed increases. Therefore, on the 2028
(1958-1962) Fund's termination date the present value of the annuity payments
the investor is entitled to receive as a result of owning accumulation units in
the sub-account of the Symetra Resource Variable Account B that invests in
shares of the Fund will be less the higher the prevailing interest rates. The
Fund's adherence to the portfolio duration target formula is intended to result
in the Fund having on its termination date net assets approximately equal to the
present value of the aggregate annuity payments investors are entitled to
receive as a result of owning accumulation units in the sub-account of the
Symetra Resource Variable Account B that invests in shares of the Fund. However,
even if a Fund successfully adheres to the formula, there is no guarantee that
it will achieve this intended result or its investment objective. Although the
Fund has no current plans to close, there is no guarantee that the Fund will
continue to accept new investments until the termination date.

As of the date of this Prospectus, based on the current U.S. Treasury Zero
Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2028
(1958-1962) Fund's portfolio duration target would have been 25.5 years.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the 2028
(1958-1962) Fund. The following additional risks could affect the value of your
investment:

· Credit Risk. The issuers of the bonds and other debt securities held by the    
  2028 (1958-1962) Fund may not be able to make interest or principal payments   
  when due. Even if these issuers are able to make interest or principal         
  payments, changes in an issuer's credit rating or the market's perception of an
  issuer's creditworthiness may also affect the value of the Fund's investment in
  that issuer by leading to greater volatility in the price of the security.     

· Credit Default Swap Risk. In a credit default swap transaction, both the 2028
  (1958-1962) Fund and its counter-party are exposed to the risk of default by   
  the other. In addition, the terms of most credit default swap transactions     
  require little or no initial investment by the seller in relation to the       
  notional amount of the swap and the corresponding risk. Therefore, small       
  changes in the market value of the reference security or group of securities   
  may produce disproportionate and substantial losses for the seller.            
  
· Derivatives Risk. Derivatives are securities, such as futures contracts, whose
  value is derived from that of other securities or indices. The 2028 (1958-1962)
  Fund's investments in derivatives may pose risks in addition to those          
  associated with investing directly in securities or other investments.         
  Derivative securities are subject to a number of risks including liquidity,    
  interest rate, market, credit and management risks, the risk of improper       
  valuation, illiquidity of the derivatives, imperfect correlations with         
  underlying investments or the Fund's other portfolio holdings, lack of         
  availability and counterparty risk. Changes in the value of the derivative may
  not correlate perfectly with the underlying asset, rate or index, and the Fund
  could lose more than the principal amount invested. An investment in           
  derivatives may not perform as anticipated by the Sub-Adviser, may not be able
  to be closed out at a favorable time or price. An investment in derivatives may
  also increase the Fund's volatility and create investment leverage. When a     
  derivative is used as a substitute or alternative to a direct cash investment,
  the transaction may not provide a return that corresponds precisely with that  
  of the cash investment; or, when used for hedging purposes, derivatives may not
  provide the anticipated protection, causing the Fund to lose money on both the
  derivatives transaction and the exposure the Fund sought to hedge.             
  
· Extension Risk. When interest rates rise, certain obligations will be paid off
  by the obligor more slowly than anticipated, causing the value of these        
  securities to fall.                                                            
  
· Foreign Investing Risk. The securities of foreign issuers may be less liquid   
  and more volatile than securities of comparable U.S. issuers. Investments in   
  securities of foreign issuers, even those publicly traded in the United States,
  may involve risks which are in addition to those inherent in domestic          
  investments. Foreign companies may not be subject to the same regulatory       
  requirements of U.S. companies, and as a consequence, there may be less        
  publicly available information about such companies. Also, foreign companies   
  may not be subject to uniform accounting, auditing, and financial reporting    
  standards and requirements comparable to those applicable to U.S. companies.   
  Foreign governments and foreign economies often are less stable than the U.S.  
  Government and the U.S. economy.                                               
  
· Interest Rate Risk. In general, the value of bonds and other debt securities   
  falls when interest rates rise. Generally, the longer the duration of a debt   
  security, the greater is the negative effect on its value when rates           
  increase. Because zero coupon debt securities do not pay interest, the market  
  value of such securities can fall more dramatically than interest-paying       
  securities of similar maturities when interest rates rise. While bonds and     
  other debt securities normally fluctuate less in price than common stocks,     
  there have been extended periods of increases in interest rates that have      
  caused significant declines in bond prices.                                    
  
· Management Risk. The 2028 (1958-1962) Fund is subject to management risk       
  because it is an actively managed portfolio. The portfolio manager's management
  practices, investment strategies, and choice of investments might not work to  
  produce the desired results and the Fund might underperform other comparable   
  funds.                                                                         
  
· Market Risk. The prices of the securities in which the 2028 (1958-1962) Fund   
  invests may decline for a number of reasons including in response to economic  
  developments and perceptions about the creditworthiness of individual          
  issuers. Longer-term bonds, in which the Fund will invest a majority of its    
  assets, are generally more volatile.                                           
  
· New Fund Risk. The 2028 (1958-1962) Fund is new with no operating history and  
  there can be no assurance that the Fund will grow to or maintain an            
  economically viable size. If the Fund does not grow to or maintain an          
  economically viable size the Board may consider various alternatives, including
  the liquidation of the Fund or the merger of the Fund into another mutual fund.

· Portfolio Duration Target Formula Risk. There is no guarantee that adherence to
  the portfolio duration target formula will result in the Fund achieving its    
  investment objective.                                                          
  
· Prepayment Risk. When interest rates fall, certain obligations will be paid off
  by the obligor more quickly than originally anticipated, and the 2028          
  (1958-1962) Fund may have to invest the proceeds in securities with lower      
  yields (this is known as Reinvestment Risk).                                   

· Termination Risk. Because the 2028 (1958-1962) Fund has a Termination Date and
  it will invest a majority of its assets in securities that mature after the    
  Termination Date, the Fund may incur liquidation costs to liquidate its        
  portfolio.                                                                     

· U.S. Government Issuer Risk. Treasury obligations may differ in their interest
  rates, maturities, times of issuance and other characteristics. Obligations of
  U.S. Government agencies and authorities are supported by varying degrees of   
  credit but generally are not backed by the full faith and credit of the U.S.   
  Government. No assurance can be given that the U.S. Government will provide    
  financial support to its agencies and authorities if it is not obligated by law
  to do so.

Performance

When the 2028 (1958-1962) Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2028 (b.1958-1962) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.

XML

Symetra Pension Reserve Fund 2020 (b. 1948-1952) (Prospectus Summary) | Symetra Pension Reserve Fund 2020 (b. 1948-1952)

Symetra Pension Reserve Fund - 2020 (b.1948-1952)

Investment Objective

The Symetra Pension Reserve Fund - 2020 (b.1948-1952) (the "2020 (1948-1952)
Fund" or the "Fund") seeks investment returns that would provide an amount on
the Fund's termination date approximately equal to the then present value of
specified lifetime annuity payments to be made to investors born in the year
range identified in the Fund's name. As a result of its investment objective,
a Pension Reserve Fund may not be a wise investment choice for an investor who
does not anticipate applying his or her accumulation to the purchase of a
lifetime annuity on or shortly after the Fund's termination date.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold
shares of the 2020 (1948-1952) Fund. The expenses shown in the table and in the
example that follow do not reflect additional fees and expenses that will be
applied at the variable annuity contract level. If those additional fees and
expenses were included, overall expenses would be higher.

SHAREHOLDER FEES (fees paid directly from your investment) N/A

ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Symetra Pension Reserve Fund 2020 (b. 1948-1952)
Management Fees		0.32%
Other Expenses	[1]	1.77%
Total Annual Fund Operating Expenses		2.09%
Less: Fee Waiver and/or Expense Reimbursement	[2]	(1.69%)
Total Annual Fund Operating Expenses after Fee Waiver and Expense Reimbursement		0.40%

Example

This Example is intended to help you compare the cost of investing in the 2020
(1948-1952) Fund with the cost of investing in other mutual funds. The Example
assumes that you invest $10,000 in the Fund for the time periods indicated and
then redeem all of your shares at the end of those periods. The Example also
assumes that your investment has a 5% return each year and that the Fund's
operating expenses remain the same (taking into account the Expense Cap and
Fee Waiver only in the first year).

Although your actual costs may be higher or lower, based on these assumptions, your costs would be:

Expense Example (USD $)	Expense Example, With Redemption, 1 Year	Expense Example, With Redemption, 3 Years
Symetra Pension Reserve Fund 2020 (b. 1948-1952)	41	491

Portfolio Turnover

The 2020 (1948-1952) Fund pays transaction costs, such as commissions, when it
buys and sells securities (or "turns over" its portfolio). A higher portfolio
turnover rate may indicate higher transaction costs and may result in higher
taxes when Fund shares are held in a taxable account. These costs, which are not
reflected in annual fund operating expenses or in the Example, affect the Fund's
performance. No portfolio turnover rate is presented for the Fund because it had
not commenced operations as of the date of this Prospectus.

Principal Investment Strategies of the Fund

The 2020 (1948-1952) Fund invests primarily in government securities and
dollar-denominated corporate debt securities rated, at the time of purchase,
in the three highest categories by an NRSRO or unrated securities that the
Sub-Adviser determines are of comparable quality. The Fund also may invest in
other types of dollar-denominated investment grade debt securities, including
money market instruments and securities of foreign issuers. Most of the
securities held by the Fund are zero coupon debt securities. Under normal market
conditions, the Sub-Adviser generally seeks to minimize credit risk by favoring
government securities and dollar-denominated corporate debt securities rated, at
the time of purchase, in the two highest categories by an NRSRO, and investing
in other permitted investments when government securities and corporate
securities in the two highest categories are not available in sufficient
quantities at a reasonable price or are not available in optimal durations or
maturities.  The Fund also may manage portfolio duration by investing in
interest rate futures contracts, options on interest rate futures contracts,
structured notes and entering into swap agreements, provided that structured
notes and swap agreements are determined by the Sub-Adviser to pose minimal
counter-party credit risk.

The 2020 (1948-1952) Fund is managed to continuously meet portfolio duration
targets that correspond to projected payments, based on actuarially determined
survivorship rates, of a single life annuity on the life of a person born in the
year-range identified in the Fund's name. The portfolio duration targets are
recalculated at least monthly based on a formula established by the Adviser
(after consultation with Symetra Life Insurance Company ("Symetra Life")) at the
Fund's inception. The formula will not change once the Fund commences
operations. (The only variables in the formula are the amount of time remaining
until each annual projected payment of the single life annuity and the
prevailing interest rates on the recalculation date. The prevailing interest
rates are derived from the U.S. Treasury Zero Coupon yield curve - sometimes by
interpolation.) Under normal market conditions, the Sub-Adviser seeks to meet
the Fund's daily portfolio duration target by first, to the extent that such
investments are available, investing in securities having cash flows similar
to the projected payments of the single life annuity and then by balancing
investments in securities with longer and shorter durations than the target
duration. The portfolio duration target generally declines for the Fund over the
life of the Fund, but will be substantially greater than zero at the Fund's
termination date. As a result, to meet the portfolio duration target, the Fund
will likely have an investment portfolio at its termination date of debt
securities of substantial remaining duration. This in turn, will result in the
market value of the Fund's investment portfolio at the termination date being
significantly influenced by prevailing interest rates. Generally speaking, the
higher the prevailing rates at the Fund's maturity, the less the Fund will
receive from selling its assets and the lower the prevailing rates, the more the
Fund will receive for selling its assets. Thus, the market value of such assets
is inversely related to prevailing interest rates.

The present value of a future series of payments decreases as the interest rate
on which the present value is computed increases. Therefore, on the 2020
(1948-1952) Fund's termination date the present value of the annuity payments
the investor is entitled to receive as a result of owning accumulation units
in the sub-account of the Symetra Resource Variable Account B that invests in
shares of the Fund will be less the higher the prevailing interest rates. The
Fund's adherence to the portfolio duration target formula is intended to result
in the Fund having on its termination date net assets approximately equal to the
present value of the aggregate annuity payments investors are entitled to
receive as a result of owning accumulation units in the sub-account of the
Symetra Resource Variable Account B that invests in shares of the Fund. However,
even if a Fund successfully adheres to the formula, there is no guarantee that
it will achieve this intended result or its investment objective. Although the
Fund has no current plans to close, there is no guarantee that the Fund will
continue to accept new investments until the termination date.

As of the date of this Prospectus, based on the current U.S. Treasury Zero
Coupon interest rate, if the Fund had been operational on May 7, 2012, the 2020
(1948-1952) Fund's portfolio duration target would have been 17.8 years.

Principal Risks of Investing in the Fund

Losing all or a portion of your investment is a risk of investing in the 2020
(1948-1952) Fund. The following additional risks could affect the value of your
investment:

· Credit Risk. The issuers of the bonds and other debt securities held by the    
  2020 (1948-1952) Fund may not be able to make interest or principal payments   
  when due. Even if these issuers are able to make interest or principal         
  payments, changes in an issuer's credit rating or the market's perception of an
  issuer's creditworthiness may also affect the value of the Fund's investment in
  that issuer by leading to greater volatility in the price of the security.     

· Credit Default Swap Risk. In a credit default swap transaction, both the 2020
  (1948-1952) Fund and its counter-party are exposed to the risk of default by   
  the other. In addition, the terms of most credit default swap transactions     
  require little or no initial investment by the seller in relation to the       
  notional amount of the swap and the corresponding risk. Therefore, small       
  changes in the market value of the reference security or group of securities   
  may produce disproportionate and substantial losses for the seller.            
  
· Derivatives Risk. Derivatives are securities, such as futures contracts, whose
  value is derived from that of other securities or indices. The 2020 (1948-1952)
  Fund's investments in derivatives may pose risks in addition to those          
  associated with investing directly in securities or other investments.         
  Derivative securities are subject to a number of risks including liquidity,    
  interest rate, market, credit and management risks, the risk of improper       
  valuation, illiquidity of the derivatives, imperfect correlations with         
  underlying investments or the Fund's other portfolio holdings, lack of         
  availability and counterparty risk. Changes in the value of the derivative may
  not correlate perfectly with the underlying asset, rate or index, and the Fund
  could lose more than the principal amount invested. An investment in           
  derivatives may not perform as anticipated by the Sub-Adviser, may not be able
  to be closed out at a favorable time or price. An investment in derivatives may
  also increase the Fund's volatility and create investment leverage. When a     
  derivative is used as a substitute or alternative to a direct cash investment,
  the transaction may not provide a return that corresponds precisely with that  
  of the cash investment; or, when used for hedging purposes, derivatives may not
  provide the anticipated protection, causing the Fund to lose money on both the
  derivatives transaction and the exposure the Fund sought to hedge.             
  
· Extension Risk. When interest rates rise, certain obligations will be paid off
  by the obligor more slowly than anticipated, causing the value of these        
  securities to fall.                                                            
  
· Foreign Investing Risk. The securities of foreign issuers may be less liquid   
  and more volatile than securities of comparable U.S. issuers. Investments in   
  securities of foreign issuers, even those publicly traded in the United States,
  may involve risks which are in addition to those inherent in domestic          
  investments. Foreign companies may not be subject to the same regulatory       
  requirements of U.S. companies, and as a consequence, there may be less        
  publicly available information about such companies. Also, foreign companies   
  may not be subject to uniform accounting, auditing, and financial reporting    
  standards and requirements comparable to those applicable to U.S. companies.   
  Foreign governments and foreign economies often are less stable than the U.S.  
  Government and the U.S. economy.                                               

· Interest Rate Risk. In general, the value of bonds and other debt securities   
  falls when interest rates rise. Generally, the longer the duration of a debt   
  security, the greater is the negative effect on its value when rates           
  increase. Because zero coupon debt securities do not pay interest, the market  
  value of such securities can fall more dramatically than interest-paying       
  securities of similar maturities when interest rates rise. While bonds and     
  other debt securities normally fluctuate less in price than common stocks,     
  there have been extended periods of increases in interest rates that have      
  caused significant declines in bond prices.                                    
  
· Management Risk. The 2020 (1948-1952) Fund is subject to management risk       
  because it is an actively managed portfolio. The portfolio manager's management
  practices, investment strategies, and choice of investments might not work to  
  produce the desired results and the Fund might underperform other comparable   
  funds.                                                                         
  
· Market Risk. The prices of the securities in which the 2020 (1948-1952) Fund   
  invests may decline for a number of reasons including in response to economic  
  developments and perceptions about the creditworthiness of individual          
  issuers. Longer-term bonds, in which the Fund will invest a majority of its    
  assets, are generally more volatile.                                           
  
· New Fund Risk. The 2020 (1948-1952) Fund is new with no operating history and  
  there can be no assurance that the Fund will grow to or maintain an            
  economically viable size. If the Fund does not grow to or maintain an          
  economically viable size the Board may consider various alternatives, including
  the liquidation of the Fund or the merger of the Fund into another mutual fund.

· Portfolio Duration Target Formula Risk. There is no guarantee that adherence to
  the portfolio duration target formula will result in the Fund achieving its    
  investment objective.                                                          

· Prepayment Risk. When interest rates fall, certain obligations will be paid off
  by the obligor more quickly than originally anticipated, and the 2020          
  (1948-1952) Fund may have to invest the proceeds in securities with lower      
  yields (this is known as Reinvestment Risk).                                   

· Termination Risk. Because the 2020 (1948-1952) Fund has a Termination Date and
  it will invest a majority of its assets in securities that mature after the    
  Termination Date, the Fund may incur liquidation costs to liquidate its        
  portfolio.                                                                     

· U.S. Government Issuer Risk. Treasury obligations may differ in their interest
  rates, maturities, times of issuance and other characteristics. Obligations of
  U.S. Government agencies and authorities are supported by varying degrees of   
  credit but generally are not backed by the full faith and credit of the U.S.   
  Government. No assurance can be given that the U.S. Government will provide    
  financial support to its agencies and authorities if it is not obligated by law
  to do so.

Performance

When the 2020 (1948-1952) Fund has been in operation for a full calendar year,
performance information will be shown here. Updated performance information is
available on the Fund's website at www.symetra.com/funds or by calling the Fund
toll-free at 1-800-SYMETRA (1-800-796-3872).

[1] "Other expenses" is an estimated amount for the current fiscal year.

[2] Symetra Investment Management, Inc. (the "Adviser") has contractually agreed to waive 0.05% of its management fee (the "Fee Waiver") and also agreed to pay Fund expenses in order to limit the Fund's Other Expenses (excluding interest, taxes, brokerage commissions, capitalized expenditures, expenses related to short sales, expenses related to directed brokerage arrangements, acquired fund fees and expenses, and extraordinary expenses) to 0.13% of the average daily net assets of the Pension Reserve Fund - 2020 (b.1948-1952) (the "Expense Cap"). The Fee Waiver and the Expense Cap will remain in effect through at least April 30, 2013, and may be terminated before then only by the Board of Trustees (the "Board"). The Adviser may request recoupment of previously waived fees and paid expenses from the Fund for three years from the date they were waived or paid, as long as the Fund can make the repayment while remaining within its Expense Cap.