485BPOS

As filed with the Securities and Exchange Commission on May 22, 2018

1933 Act File No. 002-98409

1940 Act File No. 811-04325

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C.  20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933			[ X ]
	Pre-Effective Amendment No. __	[     ]
	Post-Effective Amendment No. 83	[ X ]
and/or
REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940			[ X ]
	Amendment No. 83	[ X ]
(Check appropriate box or boxes.)

FIRST INVESTORS LIFE SERIES FUNDS

(Exact Name of Registrant as Specified in Charter)

40 Wall Street

New York, New York 10005

(Address of Principal Executive Offices)   (Zip Code)

Registrant’s Telephone Number, including Area Code:  (212) 858-8000

Mary Carty, Esq.

First Investors Life Series Funds

40 Wall Street

New York, New York 10005

(Name and Address of Agent for Service)

Copy to:

Kathy K. Ingber, Esq.

K&L Gates LLP

1601 K Street, NW

Washington, D.C. 20006-1600

It is proposed that this filing will become effective (check appropriate box)

[ X ]	immediately upon filing pursuant to paragraph (b)
[     ]	on (date) pursuant to paragraph (b)
[     ]	60 days after filing pursuant to paragraph (a)(1)
[     ]	on (date) pursuant to paragraph (a)(1)
[     ]	75 days after filing pursuant to paragraph (a)(2)
[     ]	on (date) pursuant to paragraph (a)(2) of Rule 485.

If appropriate, check the following box:

[    ] This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

This amendment is being filed solely to submit exhibits containing risk/return summary information in interactive data format that is identical to the risk/return information contained in the Registrant’s prospectus that was filed with the Securities and Exchange Commission in Post-Effective Amendment No. 82 to the Registrant’s registration statement on April 27, 2018.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended (“1933 Act”), and the Investment Company Act of 1940, as amended, the Registrant represents that this Amendment meets all the requirements for effectiveness pursuant to Rule 485(b) under the 1933 Act and has duly caused this Post-Effective Amendment No. 83 to the Registration Statement on Form N-1A to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of New York, and the State of New York, on the 22nd day of May 2018.

FIRST INVESTORS LIFE SERIES FUNDS

By:	/s/ E. Blake Moore Jr.
	E. Blake Moore Jr.
	President

Pursuant to the requirements of the 1933 Act, this Post-Effective Amendment No. 83 to the Registration Statement has been signed below by the following persons in the capacities and on the dates indicated.

/s/ E. Blake Moore Jr.	President	May 22, 2018
E. Blake Moore Jr.	(Principal Executive Officer)
/s/ Joseph I. Benedek	Treasurer	May 22, 2018
Joseph I. Benedek	(Principal Financial Officer and Principal Accounting Officer)
/s/ Susan E. Artmann	Trustee	May 22, 2018
Susan E. Artmann*
/s/ Mary J. Barneby	Trustee	May 22, 2018
Mary J. Barneby*
/s/ Charles R. Barton, III	Trustee	May 22, 2018
Charles R. Barton, III*
/s/ Arthur M. Scutro, Jr.	Chairman of the Board	May 22, 2018
Arthur M. Scutro, Jr.*	And Trustee
/s/ Mark R. Ward	Trustee	May 22, 2018
Mark R. Ward*

*  By: /s/ Mary CartyMary Carty (Attorney-in-Fact)

Exhibit Index

Type	Description
EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase

XML

Document and Entity Information	Total
Prospectus:
Document Type	485BPOS
Document Period End Date	Dec. 31, 2017
Registrant Name	FIRST INVESTORS LIFE SERIES FUNDS
Entity Central Index Key	0000770906
Amendment Flag	false
Document Creation Date	Apr. 27, 2018
Document Effective Date	May 01, 2018
Prospectus Date	May 01, 2018

XML

First Investors Life Series Balanced Income Fund

First Investors Life Series Balanced Income Fund

Investment Objective:

The Fund seeks income as its primary objective and has a secondary objective of 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 Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	First Investors Life Series Balanced Income Fund First Investors Life Series Balanced Income Fund
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	First Investors Life Series Balanced Income Fund First Investors Life Series Balanced Income Fund
Management Fees	0.75%
Distribution and Service (12b-1) Fees	none
Other Expenses	0.40%
Total Annual Fund Operating Expenses	1.15%

Example

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Expense Example	1 year	3 years	5 years	10 years
First Investors Life Series Balanced Income Fund | First Investors Life Series Balanced Income Fund | USD ($)	117	365	633	1,398

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 79% of the average value of its portfolio.

Principal Investment Strategies:

The Fund allocates its assets among bonds, stocks and money market instruments. While the percentage of assets allocated to each asset class is flexible rather than fixed, under normal market conditions, the Fund invests approximately 50-70% of its net assets in bonds, money market instruments and cash and investments that provide exposure to such assets, including exchange-traded funds (“ETFs”), and approximately 30-50% of its net assets in stocks and investments that provide exposure to such assets, including ETFs.

In connection with the determination of the Fund’s allocation ranges, the Adviser considers various factors, including existing and projected market conditions for equity and fixed income securities.  Once the asset allocation for bonds, stocks and money market instruments has been set, the Adviser uses fundamental research and analysis to determine which particular investments to purchase or sell.  The percentage allocations within the above ranges may change due to, among other things, market fluctuations or reallocation decisions by Foresters Investment Management Company, Inc. (“Adviser”). Reallocations are expected to occur infrequently and only when the Fund’s investments in bonds, stocks and money market instruments fall outside of the above ranges.

The Fund’s investments in bonds are comprised primarily of investment-grade corporate bonds.  The Adviser selects bonds by first considering the outlook for the economy and interest rates, and thereafter, a particular security’s characteristics.

To a lesser extent, the Fund also invests in high yield, below investment grade corporate bonds (commonly known as “high yield” or “junk bonds”).  The Adviser has retained Muzinich & Co, Inc. (“Muzinich”) as a subadviser to manage this portion of the Fund. High yield bonds include bonds that are rated below Baa3 by Moody’s Investors Service, Inc. or below BBB- by S&P Global Ratings as well as unrated bonds that are determined by Muzinich to be of equivalent quality.  Muzinich will consider ratings assigned by ratings agencies in selecting high yield bonds, but relies principally on its own research and investment analysis. In managing its portion of the Fund, Muzinich focuses on investments it believes can generate attractive and consistent income.  Muzinich may sell a bond when it shows deteriorating fundamentals or it falls short of the portfolio manager’s expectations.  In addition, the Adviser may also invest in ETFs that could expose the Fund to high yield securities.

The Fund invests in other types of bonds and other debt securities, including U.S. Government securities and mortgage-backed securities.  The Fund may also invest in U.S. Treasury futures and options on U.S. Treasury futures to hedge against changes in interest rates.  The Fund may invest in bonds of any maturity or duration.

The Fund’s investment in stocks are normally diversified among common stocks of large-, mid- and small-size companies that offer the potential for current income or capital appreciation with an emphasis on companies that offer the potential for current income. In selecting stocks, the Adviser considers, among other things, an issuer’s financial strength, management, earnings growth potential and history (if any) of paying dividends.

The Adviser may sell a security if it becomes fully valued, its fundamentals have deteriorated, alternative investments become more attractive or if it is necessary to rebalance the portfolio.

Principal Risks:

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Allocation Risk.  The Fund may allocate assets to investment classes that underperform other classes.  For example, the Fund may be overweighted in bonds when the bond market is falling and the stock market is rising.

Credit Risk.  A debt issuer may become unable or unwilling to pay interest or principal when due.  The prices of debt securities are affected by the credit quality of the issuer and, in the case of mortgage-backed securities, the credit quality of the underlying loans.  Securities issued by U.S. Government sponsored enterprises are supported only by the credit of the issuing entity.

Derivatives Risk.  Investments in U.S. Treasury futures and options on U.S. Treasury futures to hedge against changes in interest rates involve risks, such as potential losses if interest rates do not move as expected and the potential for greater losses than if these techniques had not been used.  Investments in derivatives can increase the volatility of the Fund’s share price and may expose it to significant additional costs.  Derivatives may be difficult to sell, unwind or value.

Dividend Risk.  At times, the Fund may not be able to identify attractive dividend-paying stocks.  The income received by the Fund will fluctuate due to the amount of dividends that companies elect to pay, which could adversely affect the Fund’s ability to pay dividends and its share price.

Exchange-Traded Funds Risk. The risks of investing in an ETF typically reflect the risks of the instruments in which the ETF invests. In addition, because ETFs are investment companies, the Fund will bear its proportionate share of the fees and expenses of an investment in an ETF. As a result, the Fund’s expenses may be higher and performance may be lower.

High Yield Securities Risk.  High yield debt securities (commonly known as “junk bonds”), have greater credit risk than higher quality debt securities because their issuers may not be as financially strong.  High yield securities are inherently speculative due to the risk associated with the issuer’s ability to make principal and interest payments.  During times of economic stress, high yield securities issuers may be unable to access credit to refinance their bonds or meet their credit obligations.

Interest Rate Risk.  In general, when interest rates rise, the market value of a debt security declines, and when interest rates decline, the market value of a debt security increases.  Interest rates across the U.S. economy have recently increased and may continue to increase, thereby heightening the Fund’s exposure to the risks associated with rising interest rates.  Securities with longer maturities and durations are generally more sensitive to interest rate changes.

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  Similarly, bond prices fluctuate in value with changes in interest rates, the economy and circumstances directly involving the issuers .  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.  Certain investments may be difficult or impossible to sell at a favorable time or price when the Fund requires liquidity to make redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with stocks of mid- and small-size companies is generally greater than that associated with stocks of larger, more established companies because stocks of mid- and small-size companies tend to experience sharper price fluctuations.  At times, it may be difficult to sell mid-to small-size company stocks at reasonable prices.

Prepayment and Extension Risk.  When interest rates decline, borrowers tend to refinance their mortgages and the mortgages that back these mortgage-backed securities suffer a higher rate of prepayment.  This could cause a decrease in the Fund’s income and share price.  Conversely, when interest rates rise borrowers tend to repay their mortgages less quickly, which will generally increase both the Fund’s sensitivity to rising interest rates and its potential for price declines.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Performance:

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for the 1-year and Life of Fund periods compare to those of an index that is a broad measure of market performance for equity securities and an index that is a broad measure of market performance for fixed-income securities.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.  Prior to May 1, 2018, Muzinich did not serve as a subadviser to the Fund.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.

Total Annual Returns For Calendar Years Ended December 31

During the periods shown, the highest quarterly return was 3.59% (for the quarter ended December 31, 2017) and the lowest quarterly return was -0.38% (for the quarter ended December 31, 2016).

Average Annual Total Returns For Periods Ended December 31, 2017

Average Annual Returns - First Investors Life Series Balanced Income Fund	1 Year	Life of Fund
First Investors Life Series Balanced Income Fund (Inception Date: 11/2/15)	9.57%	6.63%
S&P 500 Index (reflects no deduction for fees, expenses or taxes)	21.83%	14.74%
BofA Merrill Lynch U.S. Corporate, Government & Mortgage Index (reflects no deduction for fees, expenses or taxes)	3.63%	2.58%

XML

Label

Element

Value

First Investors Life Series Balanced Income Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

First Investors Life Series Balanced Income Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective:

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks income as its primary objective and has a secondary objective of capital appreciation.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund:

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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 [Text Block]

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 79% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

79.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund allocates its assets among bonds, stocks and money market instruments. While the percentage of assets allocated to each asset class is flexible rather than fixed, under normal market conditions, the Fund invests approximately 50-70% of its net assets in bonds, money market instruments and cash and investments that provide exposure to such assets, including exchange-traded funds (“ETFs”), and approximately 30-50% of its net assets in stocks and investments that provide exposure to such assets, including ETFs.

In connection with the determination of the Fund’s allocation ranges, the Adviser considers various factors, including existing and projected market conditions for equity and fixed income securities.  Once the asset allocation for bonds, stocks and money market instruments has been set, the Adviser uses fundamental research and analysis to determine which particular investments to purchase or sell.  The percentage allocations within the above ranges may change due to, among other things, market fluctuations or reallocation decisions by Foresters Investment Management Company, Inc. (“Adviser”). Reallocations are expected to occur infrequently and only when the Fund’s investments in bonds, stocks and money market instruments fall outside of the above ranges.

The Fund’s investments in bonds are comprised primarily of investment-grade corporate bonds.  The Adviser selects bonds by first considering the outlook for the economy and interest rates, and thereafter, a particular security’s characteristics.

To a lesser extent, the Fund also invests in high yield, below investment grade corporate bonds (commonly known as “high yield” or “junk bonds”).  The Adviser has retained Muzinich & Co, Inc. (“Muzinich”) as a subadviser to manage this portion of the Fund. High yield bonds include bonds that are rated below Baa3 by Moody’s Investors Service, Inc. or below BBB- by S&P Global Ratings as well as unrated bonds that are determined by Muzinich to be of equivalent quality.  Muzinich will consider ratings assigned by ratings agencies in selecting high yield bonds, but relies principally on its own research and investment analysis. In managing its portion of the Fund, Muzinich focuses on investments it believes can generate attractive and consistent income.  Muzinich may sell a bond when it shows deteriorating fundamentals or it falls short of the portfolio manager’s expectations.  In addition, the Adviser may also invest in ETFs that could expose the Fund to high yield securities.

The Fund invests in other types of bonds and other debt securities, including U.S. Government securities and mortgage-backed securities.  The Fund may also invest in U.S. Treasury futures and options on U.S. Treasury futures to hedge against changes in interest rates.  The Fund may invest in bonds of any maturity or duration.

The Fund’s investment in stocks are normally diversified among common stocks of large-, mid- and small-size companies that offer the potential for current income or capital appreciation with an emphasis on companies that offer the potential for current income. In selecting stocks, the Adviser considers, among other things, an issuer’s financial strength, management, earnings growth potential and history (if any) of paying dividends.

The Adviser may sell a security if it becomes fully valued, its fundamentals have deteriorated, alternative investments become more attractive or if it is necessary to rebalance the portfolio.

Risk [Heading]

rr_RiskHeading

Principal Risks:

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Allocation Risk.  The Fund may allocate assets to investment classes that underperform other classes.  For example, the Fund may be overweighted in bonds when the bond market is falling and the stock market is rising.

Credit Risk.  A debt issuer may become unable or unwilling to pay interest or principal when due.  The prices of debt securities are affected by the credit quality of the issuer and, in the case of mortgage-backed securities, the credit quality of the underlying loans.  Securities issued by U.S. Government sponsored enterprises are supported only by the credit of the issuing entity.

Derivatives Risk.  Investments in U.S. Treasury futures and options on U.S. Treasury futures to hedge against changes in interest rates involve risks, such as potential losses if interest rates do not move as expected and the potential for greater losses than if these techniques had not been used.  Investments in derivatives can increase the volatility of the Fund’s share price and may expose it to significant additional costs.  Derivatives may be difficult to sell, unwind or value.

Dividend Risk.  At times, the Fund may not be able to identify attractive dividend-paying stocks.  The income received by the Fund will fluctuate due to the amount of dividends that companies elect to pay, which could adversely affect the Fund’s ability to pay dividends and its share price.

Exchange-Traded Funds Risk. The risks of investing in an ETF typically reflect the risks of the instruments in which the ETF invests. In addition, because ETFs are investment companies, the Fund will bear its proportionate share of the fees and expenses of an investment in an ETF. As a result, the Fund’s expenses may be higher and performance may be lower.

High Yield Securities Risk.  High yield debt securities (commonly known as “junk bonds”), have greater credit risk than higher quality debt securities because their issuers may not be as financially strong.  High yield securities are inherently speculative due to the risk associated with the issuer’s ability to make principal and interest payments.  During times of economic stress, high yield securities issuers may be unable to access credit to refinance their bonds or meet their credit obligations.

Interest Rate Risk.  In general, when interest rates rise, the market value of a debt security declines, and when interest rates decline, the market value of a debt security increases.  Interest rates across the U.S. economy have recently increased and may continue to increase, thereby heightening the Fund’s exposure to the risks associated with rising interest rates.  Securities with longer maturities and durations are generally more sensitive to interest rate changes.

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  Similarly, bond prices fluctuate in value with changes in interest rates, the economy and circumstances directly involving the issuers .  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.  Certain investments may be difficult or impossible to sell at a favorable time or price when the Fund requires liquidity to make redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with stocks of mid- and small-size companies is generally greater than that associated with stocks of larger, more established companies because stocks of mid- and small-size companies tend to experience sharper price fluctuations.  At times, it may be difficult to sell mid-to small-size company stocks at reasonable prices.

Prepayment and Extension Risk.  When interest rates decline, borrowers tend to refinance their mortgages and the mortgages that back these mortgage-backed securities suffer a higher rate of prepayment.  This could cause a decrease in the Fund’s income and share price.  Conversely, when interest rates rise borrowers tend to repay their mortgages less quickly, which will generally increase both the Fund’s sensitivity to rising interest rates and its potential for price declines.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Risk Lose Money [Text]

rr_RiskLoseMoney

You can lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance:

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for the 1-year and Life of Fund periods compare to those of an index that is a broad measure of market performance for equity securities and an index that is a broad measure of market performance for fixed-income securities.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.  Prior to May 1, 2018, Muzinich did not serve as a subadviser to the Fund.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the Fund.

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total Annual Returns For Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown, the highest quarterly return was 3.59% (for the quarter ended December 31, 2017) and the lowest quarterly return was -0.38% (for the quarter ended December 31, 2016).

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

The highest quarterly return was 3.59% (for the quarter ended December 31, 2017)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Dec. 31, 2017

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

3.59%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

The lowest quarterly return was -0.38% (for the quarter ended December 31, 2016)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2016

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(0.38%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns For Periods Ended December 31, 2017

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

First Investors Life Series Balanced Income Fund | S&P 500 Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

21.83%

Life of Fund

rr_AverageAnnualReturnSinceInception

14.74%

First Investors Life Series Balanced Income Fund | BofA Merrill Lynch U.S. Corporate, Government & Mortgage Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

3.63%

Life of Fund

rr_AverageAnnualReturnSinceInception

2.58%

First Investors Life Series Balanced Income Fund | First Investors Life Series Balanced Income Fund

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.75%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.40%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.15%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 117

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

365

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

633

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,398

Annual Return 2016

rr_AnnualReturn2016

6.71%

Annual Return 2017

rr_AnnualReturn2017

9.57%

1 Year

rr_AverageAnnualReturnYear01

9.57%

Life of Fund

rr_AverageAnnualReturnSinceInception

6.63%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 02, 2015

XML

First Investors Life Series Covered Call Strategy Fund

First Investors Life Series Covered Call Strategy Fund

Investment Objective:

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 Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	First Investors Life Series Covered Call Strategy Fund First Investors Life Series Covered Call Strategy Fund
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	First Investors Life Series Covered Call Strategy Fund First Investors Life Series Covered Call Strategy Fund
Management Fees	0.75%
Distribution and Service (12b-1) Fees	none
Other Expenses	0.31%
Total Annual Fund Operating Expenses	1.06%

Example

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Expense Example	1 year	3 years	5 years	10 years
First Investors Life Series Covered Call Strategy Fund | First Investors Life Series Covered Call Strategy Fund | USD ($)	108	337	585	1,294

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 143% of the average value of its portfolio.

Principal Investment Strategies:

The Fund invests in a portfolio of equity securities and writes (sells) call options on those securities.  Under normal circumstances, the Fund writes (sells) call options on at least 80% of the Fund’s total assets.  The Fund normally writes (sells) covered call options listed on U.S. exchanges on the equity securities held by the Fund to seek to lower the overall volatility of the Fund’s portfolio, protect the Fund from market declines and generate income.  The call options written (sold) by the Fund will generally have an exercise price that is above the market price of the underlying security at the time the option is written (sold).  The Fund’s equity investments consist primarily of common stocks of large-size U.S. companies, certain of which may pay dividends, and U.S. dollar-denominated equity securities of foreign issuers (i.e., American Depositary Receipts (“ADRs”)) traded on U.S. securities exchanges.  To a lesser extent, the Fund may also invest in and write (sell) covered call options on securities of mid- and small-capitalization issuers and exchange-traded funds (“ETFs”) that track certain market indices, such as the S&P 500. The nature of the Fund is such that it may be expected to underperform equity markets during periods of sharply rising equity prices; conversely, the Fund seeks to reduce losses relative to equity markets during periods of declining equity prices.

A call option gives the purchaser of the option the right to buy, and the writer, in this case, the Fund, the obligation to sell, the underlying security at the exercise price at any time prior to the expiration of the contract, regardless of the market price of the underlying security during the option period. Covered call options may be sold up to the number of shares of the equity securities held by the Fund.

In selecting investments, the Fund’s subadviser considers the following, among other criteria: a) companies in an industry with a large market share or significant revenues that fit the Fund’s investment strategy; b) companies with new products or new management to replace underperforming management; c) recent or anticipated fundamental improvements in industry environment; and d) companies that are out of favor.  Call options written by the Fund are designed to create income, lower the overall volatility of the Fund’s portfolio and mitigate the impact of market declines.  The Fund’s subadviser considers several factors when writing (selling) call options, including the overall equity market outlook, sector and/or industry attractiveness, individual security considerations, and relative and/or historical levels of option premiums.

The Fund may sell a security based on the following, among other criteria: a) an actual or anticipated significant decline in an issuer’s profitability and/or a significant negative outlook from management; b) a large appreciation in the stock price that leads to overvaluation relative to itself and its peers historically; c) significant management turnover at the senior level; or d) an industry-wide decrease in demand for an issuer’s products or services.  The subadviser writes call options based upon the subadviser’s outlook on the economy and stock market and analysis of individual stocks, which can impact the exercise price and expiration of a call option.  Generally, higher implied volatility will lead to longer expirations, locking in potentially higher call premiums, whereas lower implied volatility will tend to lead to shorter-dated options.  The writing of covered call options may result in frequent trading and a high portfolio turnover rate.

Principal Risks:

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

American Depositary Receipts Risk.  ADRs may involve many of the same risks as direct investments in foreign securities, including currency exchange fluctuations, less liquidity, more volatility, different governmental regulations, and the potential for political and economic instability.

Call Options Risk.  Writing call options involves risks, such as potential losses if equity markets or an individual equity security do not move as expected and the potential for greater losses than if these techniques had not been used.  By writing covered call options, the Fund will give up the opportunity to benefit from potential increases in the value of a Fund asset above the exercise price, but will bear the risk of declines in the value of the asset. Writing call options may expose the Fund to significant additional costs.  Derivatives may be difficult to sell, unwind or value.

Dividend Risk.  At times, the Fund may not be able to identify attractive dividend-paying stocks.  The income received by the Fund will also fluctuate due to the amount of dividends that companies elect to pay, which could adversely affect the Fund’s ability to pay dividends and its share price.

Exchange-Traded Funds Risk.  The risks of investing in securities of ETFs typically reflect the risks of the types of instruments in which the ETF invests. In addition, because ETFs are investment companies, the Fund will bear its proportionate share of the fees and expenses of an investment in an ETF. As a result, the Fund’s operating expenses may be higher and performance may be lower.

High Portfolio Turnover and Frequent Trading Risk.  High portfolio turnover could increase the Fund’s transaction costs and negatively impact performance.

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or a change in interest rates.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling investments to meet redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with stocks of mid- and small-size companies is generally greater than that associated with stocks of larger, more established companies because stocks of mid- and small-size companies tend to experience sharper price fluctuations.  At times, it may be difficult to sell mid- to small-size company stocks at reasonable prices.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Performance:

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows the Fund’s performance for the past calendar year.  The table shows how the Fund’s average annual returns for the 1-year and Life of Fund periods compare to those of a broad measure of market performance and also to an index that reflects a buy-write strategy using S&P 500 Index call options.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.  

Total Annual Returns For Calendar Year Ended December 31

During the period shown, the highest quarterly return was 3.93% (for the quarter ended December 31, 2017) and the lowest quarterly return was 0.46% (for the quarter ended June 30, 2017).

Average Annual Total Returns For Periods Ended December 31, 2017

Average Annual Returns - First Investors Life Series Covered Call Strategy Fund	1 Year	Life of Fund
First Investors Life Series Covered Call Strategy Fund (Inception Date: 5/2/16)	11.07%	9.82%
S&P 500 Index (reflects no deduction for fees, expenses or taxes)	21.83%	19.18%
Cboe S&P 500 BuyWrite Index (reflects no deduction for fees, expenses or taxes)	13.00%	12.37%

XML

Label

Element

Value

First Investors Life Series Covered Call Strategy Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

First Investors Life Series Covered Call Strategy Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective:

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term capital appreciation.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund:

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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 [Text Block]

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 143% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

143.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund invests in a portfolio of equity securities and writes (sells) call options on those securities.  Under normal circumstances, the Fund writes (sells) call options on at least 80% of the Fund’s total assets.  The Fund normally writes (sells) covered call options listed on U.S. exchanges on the equity securities held by the Fund to seek to lower the overall volatility of the Fund’s portfolio, protect the Fund from market declines and generate income.  The call options written (sold) by the Fund will generally have an exercise price that is above the market price of the underlying security at the time the option is written (sold).  The Fund’s equity investments consist primarily of common stocks of large-size U.S. companies, certain of which may pay dividends, and U.S. dollar-denominated equity securities of foreign issuers (i.e., American Depositary Receipts (“ADRs”)) traded on U.S. securities exchanges.  To a lesser extent, the Fund may also invest in and write (sell) covered call options on securities of mid- and small-capitalization issuers and exchange-traded funds (“ETFs”) that track certain market indices, such as the S&P 500. The nature of the Fund is such that it may be expected to underperform equity markets during periods of sharply rising equity prices; conversely, the Fund seeks to reduce losses relative to equity markets during periods of declining equity prices.

A call option gives the purchaser of the option the right to buy, and the writer, in this case, the Fund, the obligation to sell, the underlying security at the exercise price at any time prior to the expiration of the contract, regardless of the market price of the underlying security during the option period. Covered call options may be sold up to the number of shares of the equity securities held by the Fund.

In selecting investments, the Fund’s subadviser considers the following, among other criteria: a) companies in an industry with a large market share or significant revenues that fit the Fund’s investment strategy; b) companies with new products or new management to replace underperforming management; c) recent or anticipated fundamental improvements in industry environment; and d) companies that are out of favor.  Call options written by the Fund are designed to create income, lower the overall volatility of the Fund’s portfolio and mitigate the impact of market declines.  The Fund’s subadviser considers several factors when writing (selling) call options, including the overall equity market outlook, sector and/or industry attractiveness, individual security considerations, and relative and/or historical levels of option premiums.

The Fund may sell a security based on the following, among other criteria: a) an actual or anticipated significant decline in an issuer’s profitability and/or a significant negative outlook from management; b) a large appreciation in the stock price that leads to overvaluation relative to itself and its peers historically; c) significant management turnover at the senior level; or d) an industry-wide decrease in demand for an issuer’s products or services.  The subadviser writes call options based upon the subadviser’s outlook on the economy and stock market and analysis of individual stocks, which can impact the exercise price and expiration of a call option.  Generally, higher implied volatility will lead to longer expirations, locking in potentially higher call premiums, whereas lower implied volatility will tend to lead to shorter-dated options.  The writing of covered call options may result in frequent trading and a high portfolio turnover rate.

Risk [Heading]

rr_RiskHeading

Principal Risks:

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

American Depositary Receipts Risk.  ADRs may involve many of the same risks as direct investments in foreign securities, including currency exchange fluctuations, less liquidity, more volatility, different governmental regulations, and the potential for political and economic instability.

Call Options Risk.  Writing call options involves risks, such as potential losses if equity markets or an individual equity security do not move as expected and the potential for greater losses than if these techniques had not been used.  By writing covered call options, the Fund will give up the opportunity to benefit from potential increases in the value of a Fund asset above the exercise price, but will bear the risk of declines in the value of the asset. Writing call options may expose the Fund to significant additional costs.  Derivatives may be difficult to sell, unwind or value.

Dividend Risk.  At times, the Fund may not be able to identify attractive dividend-paying stocks.  The income received by the Fund will also fluctuate due to the amount of dividends that companies elect to pay, which could adversely affect the Fund’s ability to pay dividends and its share price.

Exchange-Traded Funds Risk.  The risks of investing in securities of ETFs typically reflect the risks of the types of instruments in which the ETF invests. In addition, because ETFs are investment companies, the Fund will bear its proportionate share of the fees and expenses of an investment in an ETF. As a result, the Fund’s operating expenses may be higher and performance may be lower.

High Portfolio Turnover and Frequent Trading Risk.  High portfolio turnover could increase the Fund’s transaction costs and negatively impact performance.

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or a change in interest rates.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling investments to meet redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with stocks of mid- and small-size companies is generally greater than that associated with stocks of larger, more established companies because stocks of mid- and small-size companies tend to experience sharper price fluctuations.  At times, it may be difficult to sell mid- to small-size company stocks at reasonable prices.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Risk Lose Money [Text]

rr_RiskLoseMoney

You can lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance:

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows the Fund’s performance for the past calendar year.  The table shows how the Fund’s average annual returns for the 1-year and Life of Fund periods compare to those of a broad measure of market performance and also to an index that reflects a buy-write strategy using S&P 500 Index call options.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.  

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The following bar chart and table provide some indication of the risks of investing in the Fund.

Bar Chart [Heading]

rr_BarChartHeading

Total Annual Returns For Calendar Year Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the period shown, the highest quarterly return was 3.93% (for the quarter ended December 31, 2017) and the lowest quarterly return was 0.46% (for the quarter ended June 30, 2017).

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

The highest quarterly return was 3.93% (for the quarter ended December 31, 2017)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Dec. 31, 2017

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

3.93%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

The lowest quarterly return was 0.46% (for the quarter ended June 30, 2017)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Jun. 30, 2017

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

0.46%

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns For Periods Ended December 31, 2017

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

First Investors Life Series Covered Call Strategy Fund | S&P 500 Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

21.83%

Life of Fund

rr_AverageAnnualReturnSinceInception

19.18%

First Investors Life Series Covered Call Strategy Fund | Cboe S&P 500 BuyWrite Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

13.00%

Life of Fund

rr_AverageAnnualReturnSinceInception

12.37%

First Investors Life Series Covered Call Strategy Fund | First Investors Life Series Covered Call Strategy Fund

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.75%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.31%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.06%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 108

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

337

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

585

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,294

Annual Return 2017

rr_AnnualReturn2017

11.07%

1 Year

rr_AverageAnnualReturnYear01

11.07%

Life of Fund

rr_AverageAnnualReturnSinceInception

9.82%

Inception Date

rr_AverageAnnualReturnInceptionDate

May 02, 2016

XML

First Investors Life Series Equity Income Fund

First Investors Life Series Equity Income Fund

Investment Objective:

The Fund seeks total return.

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 Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	First Investors Life Series Equity Income Fund First Investors Life Series Equity Income Fund
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	First Investors Life Series Equity Income Fund First Investors Life Series Equity Income Fund
Management Fees	0.75%
Distribution and Service (12b-1) Fees	none
Other Expenses	0.06%
Total Annual Fund Operating Expenses	0.81%

Example

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Expense Example	1 year	3 years	5 years	10 years
First Investors Life Series Equity Income Fund | First Investors Life Series Equity Income Fund | USD ($)	83	259	450	1,002

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 18% of the average value of its portfolio.

Principal Investment Strategies:

The Fund invests, under normal circumstances, primarily in dividend-paying stocks of companies that the Fund believes are undervalued in the market relative to their long term potential.  Under normal circumstances, the Fund will invest at least 80% of its net assets (including any borrowings for investment purposes) in equities.  For purposes of this 80% policy, equities may include common stock, preferred stock, equity-based exchange-traded funds (ETFs) and instruments that are convertible into common stock, or other instruments that represent an equity position in an issuer.  The Fund normally will diversify its assets among dividend-paying stocks of large-, mid- and small-size companies.  The Fund may also invest in stocks of companies of any size that do not pay dividends, but have the potential of paying dividends in the future if they appear to be undervalued.

The Fund may write (sell) covered call options on the securities it holds to generate income.  A call option gives the purchaser of the option the right to buy, and the writer, in this case, the Fund, the obligation to sell, the underlying security at the exercise price at any time prior to the expiration of the contract, regardless of the market price of the underlying security during the option period.

The Fund generally uses a “bottom-up” approach in attempting to identify stocks that are undervalued.  This means that the Fund generally identifies potential investments through fundamental research and analysis which includes, among other things, analyzing a company’s balance sheet, cash flow statements and competition within a company’s industry.  The Fund also assesses a company’s corporate strategy and whether the company is operating in the interests of shareholders, as well as, analyzing economic trends, interest rates, and industry diversification.

The Fund may sell a security if it becomes fully valued, its fundamentals have deteriorated or alternative investment opportunities become more attractive.

Principal Risks:

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Call Options Risk. Writing call options involves risks, such as potential losses if equity markets or an individual equity security do not move as expected and the potential for greater losses than if these techniques had not been used. By writing covered call options, the Fund will give up the opportunity to benefit from potential increases in the value of a Fund asset above the exercise price, but will bear the risk of declines in the value of the asset. Writing call options may expose the Fund to significant additional costs. Derivatives may be difficult to sell, unwind or value.

Dividend Risk.  At times, the Fund may not be able to identify attractive dividend-paying stocks.  The income received by the Fund will also fluctuate due to the amount of dividends that companies elect to pay, which could adversely affect the funds ability to pay dividends and its share price. 

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  While dividend-paying stocks are generally considered less volatile than other stocks, there can be no guarantee that the Fund’s overall portfolio will be less volatile than the general stock market. 

Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with stocks of mid- and small-size companies is generally greater than that associated with stocks of larger, more established companies because stocks of mid- and small-size companies tend to experience sharper price fluctuations.  At times, it may be difficult to sell mid-to small-size company stocks at reasonable prices.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

Undervalued Securities Risk.  The Fund seeks to invest in securities that are undervalued and that will rise in value due to anticipated events or changes in investor perceptions.  If these developments do not occur, the market price of these securities may not rise as expected or may fall.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Performance:

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown. 

Total Annual Returns For Calendar Years Ended December 31

During the periods shown, the highest quarterly return was 14.39% (for the quarter ended September 30, 2009) and the lowest quarterly return was -19.03% (for the quarter ended December 31, 2008).

Average Annual Total Returns For Periods Ended December 31, 2017

Average Annual Returns - First Investors Life Series Equity Income Fund		1 Year	5 Years	10 Years
First Investors Life Series Equity Income Fund		15.52%	12.85%	7.27%
Russell 1000 Value Index (reflects no deduction for fees, expenses or taxes)	[1]	13.67%	14.04%	7.10%
S&P 500 Index (reflects no deduction for fees, expenses or taxes)		21.83%	15.79%	8.50%

[1] The Fund changed its primary broad based securities index to the Russell 1000 Value Index from the S&P 500 Index as of May 1, 2018. The Fund elected to use the new index because it more closely reflects the Fund's investment strategies.

XML

Label

Element

Value

First Investors Life Series Equity Income Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

First Investors Life Series Equity Income Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective:

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks total return.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund:

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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 [Text Block]

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 18% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

18.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund invests, under normal circumstances, primarily in dividend-paying stocks of companies that the Fund believes are undervalued in the market relative to their long term potential.  Under normal circumstances, the Fund will invest at least 80% of its net assets (including any borrowings for investment purposes) in equities.  For purposes of this 80% policy, equities may include common stock, preferred stock, equity-based exchange-traded funds (ETFs) and instruments that are convertible into common stock, or other instruments that represent an equity position in an issuer.  The Fund normally will diversify its assets among dividend-paying stocks of large-, mid- and small-size companies.  The Fund may also invest in stocks of companies of any size that do not pay dividends, but have the potential of paying dividends in the future if they appear to be undervalued.

The Fund may write (sell) covered call options on the securities it holds to generate income.  A call option gives the purchaser of the option the right to buy, and the writer, in this case, the Fund, the obligation to sell, the underlying security at the exercise price at any time prior to the expiration of the contract, regardless of the market price of the underlying security during the option period.

The Fund generally uses a “bottom-up” approach in attempting to identify stocks that are undervalued.  This means that the Fund generally identifies potential investments through fundamental research and analysis which includes, among other things, analyzing a company’s balance sheet, cash flow statements and competition within a company’s industry.  The Fund also assesses a company’s corporate strategy and whether the company is operating in the interests of shareholders, as well as, analyzing economic trends, interest rates, and industry diversification.

The Fund may sell a security if it becomes fully valued, its fundamentals have deteriorated or alternative investment opportunities become more attractive.

Risk [Heading]

rr_RiskHeading

Principal Risks:

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Call Options Risk. Writing call options involves risks, such as potential losses if equity markets or an individual equity security do not move as expected and the potential for greater losses than if these techniques had not been used. By writing covered call options, the Fund will give up the opportunity to benefit from potential increases in the value of a Fund asset above the exercise price, but will bear the risk of declines in the value of the asset. Writing call options may expose the Fund to significant additional costs. Derivatives may be difficult to sell, unwind or value.

Dividend Risk.  At times, the Fund may not be able to identify attractive dividend-paying stocks.  The income received by the Fund will also fluctuate due to the amount of dividends that companies elect to pay, which could adversely affect the funds ability to pay dividends and its share price. 

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  While dividend-paying stocks are generally considered less volatile than other stocks, there can be no guarantee that the Fund’s overall portfolio will be less volatile than the general stock market. 

Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with stocks of mid- and small-size companies is generally greater than that associated with stocks of larger, more established companies because stocks of mid- and small-size companies tend to experience sharper price fluctuations.  At times, it may be difficult to sell mid-to small-size company stocks at reasonable prices.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

Undervalued Securities Risk.  The Fund seeks to invest in securities that are undervalued and that will rise in value due to anticipated events or changes in investor perceptions.  If these developments do not occur, the market price of these securities may not rise as expected or may fall.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Risk Lose Money [Text]

rr_RiskLoseMoney

You can lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance:

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown. 

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the Fund.

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total Annual Returns For Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown, the highest quarterly return was 14.39% (for the quarter ended September 30, 2009) and the lowest quarterly return was -19.03% (for the quarter ended December 31, 2008).

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

The highest quarterly return was 14.39% (for the quarter ended September 30, 2009)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

14.39%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

The lowest quarterly return was -19.03% (for the quarter ended December 31, 2008)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(19.03%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns For Periods Ended December 31, 2017

Performance Table Market Index Changed

rr_PerformanceTableMarketIndexChanged

The Fund changed its primary broad based securities index to the Russell 1000 Value Index from the S&P 500 Index as of May 1, 2018. The Fund elected to use the new index because it more closely reflects the Fund’s investment strategies.

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

First Investors Life Series Equity Income Fund | Russell 1000 Value Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

13.67%

^[1]

5 Years

rr_AverageAnnualReturnYear05

14.04%

^[1]

10 Years

rr_AverageAnnualReturnYear10

7.10%

^[1]

First Investors Life Series Equity Income Fund | S&P 500 Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

21.83%

5 Years

rr_AverageAnnualReturnYear05

15.79%

10 Years

rr_AverageAnnualReturnYear10

8.50%

First Investors Life Series Equity Income Fund | First Investors Life Series Equity Income Fund

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.75%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.06%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.81%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 83

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

259

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

450

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,002

Annual Return 2008

rr_AnnualReturn2008

(29.41%)

Annual Return 2009

rr_AnnualReturn2009

21.03%

Annual Return 2010

rr_AnnualReturn2010

14.32%

Annual Return 2011

rr_AnnualReturn2011

1.53%

Annual Return 2012

rr_AnnualReturn2012

11.20%

Annual Return 2013

rr_AnnualReturn2013

30.53%

Annual Return 2014

rr_AnnualReturn2014

8.26%

Annual Return 2015

rr_AnnualReturn2015

(1.03%)

Annual Return 2016

rr_AnnualReturn2016

13.28%

Annual Return 2017

rr_AnnualReturn2017

15.52%

1 Year

rr_AverageAnnualReturnYear01

15.52%

5 Years

rr_AverageAnnualReturnYear05

12.85%

10 Years

rr_AverageAnnualReturnYear10

7.27%

[1] The Fund changed its primary broad based securities index to the Russell 1000 Value Index from the S&P 500 Index as of May 1, 2018. The Fund elected to use the new index because it more closely reflects the Fund's investment strategies.

XML

First Investors Life Series Fund For Income

First Investors Life Series Fund For Income

Investment Objective:

The Fund seeks high current 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 Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	First Investors Life Series Fund For Income First Investors Life Series Fund For Income
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	First Investors Life Series Fund For Income First Investors Life Series Fund For Income
Management Fees	0.75%
Distribution and Service (12b-1) Fees	none
Other Expenses	0.14%
Total Annual Fund Operating Expenses	0.89%

Example

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Expense Example	1 year	3 years	5 years	10 years
First Investors Life Series Fund For Income | First Investors Life Series Fund For Income | USD ($)	91	284	493	1,096

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 66% of the average value of its portfolio.

Principal Investment Strategies:

The Fund primarily invests in high yield, below investment grade corporate bonds (commonly known as “high yield” or “junk bonds”).  High yield bonds include both bonds that are rated below Baa3 by Moody’s Investors Service, Inc. or below BBB- by S&P Global Ratings as well as unrated bonds that are determined by the Fund to be of equivalent quality.  High yield bonds generally provide higher income than investment grade bonds to compensate investors for their higher risk of default (i.e., failure to make required interest or principal payments).  The Fund may also invest in other high yield debt securities, such as assignments of syndicated bank loans (also known as “floating rate loans”).

Although the Fund will consider ratings assigned by ratings agencies in selecting high yield bonds, it relies principally on its own research and investment analysis.  The Fund may sell a bond when it shows deteriorating fundamentals or it falls short of the portfolio manager’s expectations.  It may also decide to continue to hold a bond (or related securities) after its issuer defaults or is subject to a bankruptcy.

Principal Risks:

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Credit Risk.  A debt issuer may become unable or unwilling to pay interest or principal when due.  The prices of debt securities are affected by the credit quality of the issuer.

Floating Rate Loan Risk.  The value of any collateral securing a floating rate loan may decline, be insufficient to meet the borrower’s obligations, or be difficult or costly to liquidate.  It may take significantly longer than 7 days for investments in floating rate loans to settle, which can adversely affect the Fund’s ability to timely honor redemptions.  In the event of a default, it may be difficult to collect on any collateral and a floating rate loan can decline significantly in value. The Fund’s access to collateral may also be limited by bankruptcy or other insolvency laws.  Although senior loans may be senior to equity and debt securities in the borrower’s capital structure, the loans may be subordinated to other obligations of the borrower or its subsidiaries.  If a floating rate loan is acquired through an assignment, the Fund may not be able to unilaterally enforce all rights and remedies under the loan and with regard to any associated collateral.  High yield floating rate loans usually are more credit sensitive.  Floating rate loans may not be considered “securities” for certain purposes of the federal securities laws and purchasers, such as the Fund, therefore, may not be entitled to rely on the anti-fraud protections of the federal securities laws.

High Yield Securities Risk.  High yield debt securities (commonly known as “junk bonds”), including floating rate loans, have greater credit risk than higher quality debt securities because their issuers may not be as financially strong.  High yield securities are inherently speculative due to the risk associated with the issuer’s ability to make principal and interest payments.  During times of economic stress, high yield securities issuers may be unable to access credit to refinance their bonds or meet their credit obligations.

Interest Rate Risk.  In general, when interest rates rise, the market value of a debt security declines, and when interest rates decline, the market value of a debt security increases.  Interest rates across the U.S. economy have recently increased and may continue to increase, thereby heightening the Fund’s exposure to the risks associated with rising interest rates.  Floating rate securities may be less sensitive than fixed-rate instruments to interest rate changes, but they could remain sensitive over the short-term to interest rate changes.  The interest rates on floating rate securities adjust periodically and may not correlate to prevailing interest rates during the periods between rate adjustments.  Securities with longer maturities and durations are generally more sensitive to interest rate changes.

Liquidity Risk.  Certain investments may be difficult or impossible to sell at a favorable time or price.  Market developments may cause the Fund’s investments to become less liquid and subject to erratic price movements. High yield securities and loans tend to be less liquid.  Floating rate loans generally are subject to legal or contractual restrictions on resale and may trade infrequently.  Assignments of bank loans and bonds also may be less liquid at times because of potential delays in the settlement process or restrictions on resale.

Market Risk.  The floating rate loan, high yield loan and bond market can experience sharp price swings due to a variety of factors, including changes in economic forecasts, stock market volatility, large sustained sales of high yield bonds by major investors, high-profile defaults or the market’s psychology.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Performance:

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.  In addition, on April 24, 2009, Muzinich & Co., Inc. (“Muzinich”) became the Fund’s subadviser.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.

Total Annual Returns For Calendar Years Ended December 31

During the periods shown, the highest quarterly return was 15.22% (for the quarter ended June 30, 2009) and the lowest quarterly return was -19.03% (for the quarter ended December 31, 2008).

Average Annual Total Returns For Periods Ended December 31, 2017

Average Annual Returns - First Investors Life Series Fund For Income	1 Year	5 Years	10 Years
First Investors Life Series Fund For Income	6.82%	4.65%	5.54%
BofA Merrill Lynch BB-B US Cash Pay High Yield Constrained Index (reflects no deduction for fees, expenses or taxes)	6.96%	5.58%	7.33%

XML

Label

Element

Value

First Investors Life Series Fund For Income

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

First Investors Life Series Fund For Income

Objective [Heading]

rr_ObjectiveHeading

Investment Objective:

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks high current income.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund:

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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 [Text Block]

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 66% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

66.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund primarily invests in high yield, below investment grade corporate bonds (commonly known as “high yield” or “junk bonds”).  High yield bonds include both bonds that are rated below Baa3 by Moody’s Investors Service, Inc. or below BBB- by S&P Global Ratings as well as unrated bonds that are determined by the Fund to be of equivalent quality.  High yield bonds generally provide higher income than investment grade bonds to compensate investors for their higher risk of default (i.e., failure to make required interest or principal payments).  The Fund may also invest in other high yield debt securities, such as assignments of syndicated bank loans (also known as “floating rate loans”).

Although the Fund will consider ratings assigned by ratings agencies in selecting high yield bonds, it relies principally on its own research and investment analysis.  The Fund may sell a bond when it shows deteriorating fundamentals or it falls short of the portfolio manager’s expectations.  It may also decide to continue to hold a bond (or related securities) after its issuer defaults or is subject to a bankruptcy.

Risk [Heading]

rr_RiskHeading

Principal Risks:

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Credit Risk.  A debt issuer may become unable or unwilling to pay interest or principal when due.  The prices of debt securities are affected by the credit quality of the issuer.

Floating Rate Loan Risk.  The value of any collateral securing a floating rate loan may decline, be insufficient to meet the borrower’s obligations, or be difficult or costly to liquidate.  It may take significantly longer than 7 days for investments in floating rate loans to settle, which can adversely affect the Fund’s ability to timely honor redemptions.  In the event of a default, it may be difficult to collect on any collateral and a floating rate loan can decline significantly in value. The Fund’s access to collateral may also be limited by bankruptcy or other insolvency laws.  Although senior loans may be senior to equity and debt securities in the borrower’s capital structure, the loans may be subordinated to other obligations of the borrower or its subsidiaries.  If a floating rate loan is acquired through an assignment, the Fund may not be able to unilaterally enforce all rights and remedies under the loan and with regard to any associated collateral.  High yield floating rate loans usually are more credit sensitive.  Floating rate loans may not be considered “securities” for certain purposes of the federal securities laws and purchasers, such as the Fund, therefore, may not be entitled to rely on the anti-fraud protections of the federal securities laws.

High Yield Securities Risk.  High yield debt securities (commonly known as “junk bonds”), including floating rate loans, have greater credit risk than higher quality debt securities because their issuers may not be as financially strong.  High yield securities are inherently speculative due to the risk associated with the issuer’s ability to make principal and interest payments.  During times of economic stress, high yield securities issuers may be unable to access credit to refinance their bonds or meet their credit obligations.

Interest Rate Risk.  In general, when interest rates rise, the market value of a debt security declines, and when interest rates decline, the market value of a debt security increases.  Interest rates across the U.S. economy have recently increased and may continue to increase, thereby heightening the Fund’s exposure to the risks associated with rising interest rates.  Floating rate securities may be less sensitive than fixed-rate instruments to interest rate changes, but they could remain sensitive over the short-term to interest rate changes.  The interest rates on floating rate securities adjust periodically and may not correlate to prevailing interest rates during the periods between rate adjustments.  Securities with longer maturities and durations are generally more sensitive to interest rate changes.

Liquidity Risk.  Certain investments may be difficult or impossible to sell at a favorable time or price.  Market developments may cause the Fund’s investments to become less liquid and subject to erratic price movements. High yield securities and loans tend to be less liquid.  Floating rate loans generally are subject to legal or contractual restrictions on resale and may trade infrequently.  Assignments of bank loans and bonds also may be less liquid at times because of potential delays in the settlement process or restrictions on resale.

Market Risk.  The floating rate loan, high yield loan and bond market can experience sharp price swings due to a variety of factors, including changes in economic forecasts, stock market volatility, large sustained sales of high yield bonds by major investors, high-profile defaults or the market’s psychology.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Risk Lose Money [Text]

rr_RiskLoseMoney

You can lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance:

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.  In addition, on April 24, 2009, Muzinich & Co., Inc. (“Muzinich”) became the Fund’s subadviser.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the Fund.

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total Annual Returns For Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown, the highest quarterly return was 15.22% (for the quarter ended June 30, 2009) and the lowest quarterly return was -19.03% (for the quarter ended December 31, 2008).

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

The highest quarterly return was 15.22% (for the quarter ended June 30, 2009)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

15.22%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

The lowest quarterly return was -19.03% (for the quarter ended December 31, 2008)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(19.03%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns For Periods Ended December 31, 2017

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

First Investors Life Series Fund For Income | BofA Merrill Lynch BB-B US Cash Pay High Yield Constrained Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

6.96%

5 Years

rr_AverageAnnualReturnYear05

5.58%

10 Years

rr_AverageAnnualReturnYear10

7.33%

First Investors Life Series Fund For Income | First Investors Life Series Fund For Income

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.75%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.14%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.89%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 91

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

284

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

493

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,096

Annual Return 2008

rr_AnnualReturn2008

(25.86%)

Annual Return 2009

rr_AnnualReturn2009

35.15%

Annual Return 2010

rr_AnnualReturn2010

13.71%

Annual Return 2011

rr_AnnualReturn2011

5.66%

Annual Return 2012

rr_AnnualReturn2012

13.51%

Annual Return 2013

rr_AnnualReturn2013

6.88%

Annual Return 2014

rr_AnnualReturn2014

0.79%

Annual Return 2015

rr_AnnualReturn2015

(1.85%)

Annual Return 2016

rr_AnnualReturn2016

11.12%

Annual Return 2017

rr_AnnualReturn2017

6.82%

1 Year

rr_AverageAnnualReturnYear01

6.82%

5 Years

rr_AverageAnnualReturnYear05

4.65%

10 Years

rr_AverageAnnualReturnYear10

5.54%

XML

First Investors Life Series Government Fund

First Investors Life Series Government Fund

Investment Objective:

The Fund seeks to achieve a significant level of current income which is consistent with security and liquidity of principal.

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 Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher. 

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	First Investors Life Series Government Fund First Investors Life Series Government Fund
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	First Investors Life Series Government Fund First Investors Life Series Government Fund
Management Fees	0.75%
Distribution and Service (12b-1) Fees	none
Other Expenses	0.15%
Total Annual Fund Operating Expenses	0.90%

Example

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Expense Example	1 year	3 years	5 years	10 years
First Investors Life Series Government Fund | First Investors Life Series Government Fund | USD ($)	92	287	498	1,108

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 42% of the average value of its portfolio.

Principal Investment Strategies:

Under normal circumstances, the Fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in securities issued or guaranteed as to payment of principal and interest by the U.S. Government, its agencies or instrumentalities (“U.S. Government Securities”).

The Fund may invest in all types of U.S. Government Securities, including (a) U.S. Treasury obligations, (b) securities issued or guaranteed by U.S. Government agencies or instrumentalities backed by the full faith and credit of the U.S. Government, such as mortgage-backed securities guaranteed by the Government National Mortgage Association (“GNMA”), and (c) securities issued or guaranteed by agencies or instrumentalities sponsored by Congress but are not guaranteed by the U.S. Government and are backed solely by the credit of the issuing agency or instrumentality or the right to borrow from the U.S. Treasury, such as mortgage-backed securities issued by the Federal National Mortgage Association (“Fannie Mae”) and Federal Home Loan Mortgage Corporation (“Freddie Mac”).  To a lesser extent, the Fund may invest in municipal securities and non-government investment grade debt securities rated AA or above by S&P Global Ratings or Aa2 or above by Moody’s Investors Service, Inc.  The Fund may also invest in U.S. Treasury futures and options on U.S. Treasury futures to hedge against changes in interest rates.

The Fund uses a “top-down” approach in making investment decisions based on its assessment of interest rates, economic and market conditions, and the relative values of different types of U.S. Government securities.  In selecting investments, the Fund considers, among other factors, maturity, yield, relative value and, in the case of mortgage-backed securities, coupon and weighted average maturity.  The Fund will usually sell an investment when there are changes in the interest rate environment that are adverse to the investment.  The Fund may engage in frequent trading which may result in high portfolio turnover.

Principal Risks:

You can lose money by investing in the Fund.  While the Fund invests in obligations that are issued or guaranteed by the U.S. Government, its agencies or instrumentalities, your investment in the Fund is not insured or guaranteed by the U.S. Government.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Call Risk.  When interest rates fall, a callable bond issuer may “call” or repay the security before its maturity and cause the Fund’s income to decline.

Credit Risk.  A debt issuer may become unable or unwilling to pay interest or principal when due.  The prices of debt securities are affected by the credit quality of the issuer and, in the case of mortgage-backed securities, the credit quality of the underlying mortgages.  Securities issued by U.S. Government-sponsored enterprises are supported only by the credit of the issuing entity.

Derivatives Risk.  Investments in U.S. Treasury futures and options on U.S. Treasury futures involve risks, such as potential losses if interest rates do not move as expected and the potential for greater losses than if these techniques had not been used.  Investments in derivatives can increase the volatility of the Fund’s share price and may expose it to significant additional costs.  Derivatives may be difficult to sell, unwind, or value.

High Portfolio Turnover and Frequent Trading Risk.  High portfolio turnover could increase the Fund’s transaction costs, and negatively impact performance.

Interest Rate Risk.  In general, when interest rates rise, the market value of a debt security declines, and when interest rates decline, the market value of a debt security increases.  Interest rates across the U.S. economy have recently increased and may continue to increase, thereby heightening the Fund’s exposure to the risks associated with rising interest rates.  Securities with longer maturities and durations are generally more sensitive to interest rate changes.

Liquidity Risk.  Certain securities, such as municipal securities, may be difficult or impossible to sell at a favorable time or price.

Market Risk.  The prices of the debt securities held by the Fund may decline in response to certain events, such as general economic and market conditions, adverse political or regulatory developments and interest rate fluctuations.  Certain conditions can threaten a municipality’s ability to raise taxes or collect revenue.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Prepayment and Extension Risk.  When interest rates decline, borrowers tend to refinance their mortgages and the mortgages that back mortgage-backed securities suffer a higher rate of prepayment.  This could cause a decrease in the Fund’s income and share price.  Conversely, when interest rates rise, borrowers tend to repay their mortgages less quickly, which will generally increase the Fund’s sensitivity to interest rates and potential for price declines.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Performance:

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.  

Total Annual Returns For Calendar Years Ended December 31

During the periods shown, the highest quarterly return was 3.83% (for the quarter ended December 31, 2008) and the lowest quarterly return was -2.74% (for the quarter ended December 31, 2016).

Average Annual Total Returns For Periods Ended December 31, 2017

Average Annual Returns - First Investors Life Series Government Fund	1 Year	5 Years	10 Years
First Investors Life Series Government Fund	1.53%	0.53%	2.58%
Citigroup U.S. Government/Mortgage Index (reflects no deduction for fees, expenses or taxes)	2.34%	1.55%	3.52%

XML

Label

Element

Value

First Investors Life Series Government Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

First Investors Life Series Government Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective:

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to achieve a significant level of current income which is consistent with security and liquidity of principal.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund:

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher. 

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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 [Text Block]

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 42% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

42.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal circumstances, the Fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in securities issued or guaranteed as to payment of principal and interest by the U.S. Government, its agencies or instrumentalities (“U.S. Government Securities”).

The Fund may invest in all types of U.S. Government Securities, including (a) U.S. Treasury obligations, (b) securities issued or guaranteed by U.S. Government agencies or instrumentalities backed by the full faith and credit of the U.S. Government, such as mortgage-backed securities guaranteed by the Government National Mortgage Association (“GNMA”), and (c) securities issued or guaranteed by agencies or instrumentalities sponsored by Congress but are not guaranteed by the U.S. Government and are backed solely by the credit of the issuing agency or instrumentality or the right to borrow from the U.S. Treasury, such as mortgage-backed securities issued by the Federal National Mortgage Association (“Fannie Mae”) and Federal Home Loan Mortgage Corporation (“Freddie Mac”).  To a lesser extent, the Fund may invest in municipal securities and non-government investment grade debt securities rated AA or above by S&P Global Ratings or Aa2 or above by Moody’s Investors Service, Inc.  The Fund may also invest in U.S. Treasury futures and options on U.S. Treasury futures to hedge against changes in interest rates.

The Fund uses a “top-down” approach in making investment decisions based on its assessment of interest rates, economic and market conditions, and the relative values of different types of U.S. Government securities.  In selecting investments, the Fund considers, among other factors, maturity, yield, relative value and, in the case of mortgage-backed securities, coupon and weighted average maturity.  The Fund will usually sell an investment when there are changes in the interest rate environment that are adverse to the investment.  The Fund may engage in frequent trading which may result in high portfolio turnover.

Risk [Heading]

rr_RiskHeading

Principal Risks:

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You can lose money by investing in the Fund.  While the Fund invests in obligations that are issued or guaranteed by the U.S. Government, its agencies or instrumentalities, your investment in the Fund is not insured or guaranteed by the U.S. Government.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Call Risk.  When interest rates fall, a callable bond issuer may “call” or repay the security before its maturity and cause the Fund’s income to decline.

Credit Risk.  A debt issuer may become unable or unwilling to pay interest or principal when due.  The prices of debt securities are affected by the credit quality of the issuer and, in the case of mortgage-backed securities, the credit quality of the underlying mortgages.  Securities issued by U.S. Government-sponsored enterprises are supported only by the credit of the issuing entity.

Derivatives Risk.  Investments in U.S. Treasury futures and options on U.S. Treasury futures involve risks, such as potential losses if interest rates do not move as expected and the potential for greater losses than if these techniques had not been used.  Investments in derivatives can increase the volatility of the Fund’s share price and may expose it to significant additional costs.  Derivatives may be difficult to sell, unwind, or value.

High Portfolio Turnover and Frequent Trading Risk.  High portfolio turnover could increase the Fund’s transaction costs, and negatively impact performance.

Interest Rate Risk.  In general, when interest rates rise, the market value of a debt security declines, and when interest rates decline, the market value of a debt security increases.  Interest rates across the U.S. economy have recently increased and may continue to increase, thereby heightening the Fund’s exposure to the risks associated with rising interest rates.  Securities with longer maturities and durations are generally more sensitive to interest rate changes.

Liquidity Risk.  Certain securities, such as municipal securities, may be difficult or impossible to sell at a favorable time or price.

Market Risk.  The prices of the debt securities held by the Fund may decline in response to certain events, such as general economic and market conditions, adverse political or regulatory developments and interest rate fluctuations.  Certain conditions can threaten a municipality’s ability to raise taxes or collect revenue.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Prepayment and Extension Risk.  When interest rates decline, borrowers tend to refinance their mortgages and the mortgages that back mortgage-backed securities suffer a higher rate of prepayment.  This could cause a decrease in the Fund’s income and share price.  Conversely, when interest rates rise, borrowers tend to repay their mortgages less quickly, which will generally increase the Fund’s sensitivity to interest rates and potential for price declines.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Risk Lose Money [Text]

rr_RiskLoseMoney

You can lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance:

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.  

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the Fund.

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total Annual Returns For Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown, the highest quarterly return was 3.83% (for the quarter ended December 31, 2008) and the lowest quarterly return was -2.74% (for the quarter ended December 31, 2016).

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

The highest quarterly return was 3.83% (for the quarter ended December 31, 2008)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Dec. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

3.83%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

The lowest quarterly return was -2.74% (for the quarter ended December 31, 2016)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2016

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(2.74%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns For Periods Ended December 31, 2017

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

First Investors Life Series Government Fund | Citigroup U.S. Government/Mortgage Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

2.34%

5 Years

rr_AverageAnnualReturnYear05

1.55%

10 Years

rr_AverageAnnualReturnYear10

3.52%

First Investors Life Series Government Fund | First Investors Life Series Government Fund

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.75%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.15%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.90%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 92

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

287

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

498

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,108

Annual Return 2008

rr_AnnualReturn2008

6.93%

Annual Return 2009

rr_AnnualReturn2009

4.28%

Annual Return 2010

rr_AnnualReturn2010

4.82%

Annual Return 2011

rr_AnnualReturn2011

5.41%

Annual Return 2012

rr_AnnualReturn2012

1.95%

Annual Return 2013

rr_AnnualReturn2013

(2.47%)

Annual Return 2014

rr_AnnualReturn2014

3.14%

Annual Return 2015

rr_AnnualReturn2015

0.04%

Annual Return 2016

rr_AnnualReturn2016

0.48%

Annual Return 2017

rr_AnnualReturn2017

1.53%

1 Year

rr_AverageAnnualReturnYear01

1.53%

5 Years

rr_AverageAnnualReturnYear05

0.53%

10 Years

rr_AverageAnnualReturnYear10

2.58%

XML

First Investors Life Series Government Cash Management Fund

First Investors Life Series Government Cash Management Fund

Investment Objective:

The Fund seeks to earn a high rate of current income consistent with the preservation of capital and maintenance of liquidity.

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 Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	First Investors Life Series Government Cash Management Fund First Investors Life Series Government Cash Management Fund
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	First Investors Life Series Government Cash Management Fund First Investors Life Series Government Cash Management Fund
Management Fees	0.75%
Distribution and Service (12b-1) Fees	none
Other Expenses	0.44%
Total Annual Fund Operating Expenses	1.19%

Example

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Expense Example	1 year	3 years	5 years	10 years
First Investors Life Series Government Cash Management Fund | First Investors Life Series Government Cash Management Fund | USD ($)	121	378	654	1,443

Principal Investment Strategies:

The Fund intends to operate as a “government money market fund” as defined in Rule 2a-7 under the Investment Company Act of 1940 as amended. The Fund will invest at least 99.5% of its total assets in (i) U.S. government securities; (ii) cash; and/or (iii) repurchase agreements that are collateralized fully by cash and/or U.S. government securities. In addition, under normal circumstances, the Fund will invest at least 80% of its net assets, including any borrowings for investment purposes, in U.S. government securities and repurchase agreements collateralized fully by cash or U.S. government securities.  U.S. government securities include: U.S. Treasury bills and notes; obligations issued by the U.S. government, its agencies or instrumentalities, including securities issued by entities chartered by Congress that are not issued or guaranteed by the U.S. Treasury, including the Federal National Mortgage Association, Federal Home Loan Mortgage Corporation, Federal Home Loan Banks and Federal Farm Credit Banks; and obligations issued by issuers that are guaranteed as to principal or interest by the U.S. government, its agencies or instrumentalities, including the Government National Mortgage Association.  The Fund may invest in fixed, variable and floating rate instruments.  The Fund generally invests in securities with remaining maturities of 397 days or less.

The Fund’s portfolio is managed to meet regulatory requirements that permit the Fund to maintain a stable net asset value (“NAV”) of $1.00 per share.  These include requirements relating to the credit quality, maturity, liquidity and diversification of the Fund’s investments.

Principal Risks:

You could lose money by investing in the Fund.  Although the Fund seeks to preserve a $1.00 per share net asset value, it cannot guarantee it will do so.  An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.  The Fund’s sponsor has no legal obligation to provide financial support to the Fund, and you should not expect that the sponsor will provide support to the Fund at any time.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Credit Risk.  The U.S. government securities the Fund invests in may or may not be backed by the full faith and credit of the U.S. government.  Securities issued by U.S. government sponsored enterprises are supported only by the credit of the issuing entity.  The value of an investment will decline if there is a default by or a deterioration in the credit quality of the issuer or a provider of a credit enhancement or demand feature.  This could cause the Fund's NAV to decline below $1.00 per share.

Interest Rate Risk.  Like the values of other debt instruments, the market values of U.S government securities are affected by changes in interest rates.  When interest rates rise, the market values of U.S. government securities generally decline.  This could cause the Fund’s NAV to decline below $1.00 per share.  Interest rates across the U.S. economy have recently increased and may continue to increase, thereby heightening the Fund’s exposure to the risks associated with rising interest rates.

Liquidity Risk.  Certain investments may be difficult or impossible to sell at a favorable time or price.  Market developments may cause the Fund’s investments to become less liquid and subject to erratic price movements, which may have an adverse effect on the Fund’s ability to maintain a $1.00 share price.

Market Risk.  The prices of the debt securities held by the Fund may decline in response to certain events, such as general economic and market conditions, adverse political or regulatory developments and interest rate fluctuations,.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions or cause the Fund’s NAV to decline below $1.00 per share.  Supply issues could arise within the U.S. Treasury securities market as demand increases for U.S. government securities.

Repurchase Agreement Risk.  If the seller in a repurchase agreement transaction defaults on its obligation to repurchase a security, the Fund may suffer delays, incur costs and lose money in exercising its rights.

Yield Risk.  The yields received by the Fund on its investments will generally decline as interest rates decline.

Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.

Performance:

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows the Fund’s average annual returns for 1, 5, and 10 years.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Prior to October 3, 2016, the Fund invested in certain securities that are no longer permissible for “government money market funds” under Rule 2a-7.  The performance below may have been different if the current limit on the Fund’s investments had been in effect.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.

Total Annual Returns For Calendar Years Ended December 31

During the periods shown, the highest quarterly return was 0.77% (for the quarter ended March 31, 2008) and the lowest quarterly return was 0.00% (for each quarter beginning with quarter ended December 31, 2009 through the quarter ended June 30, 2017).

Average Annual Total Returns For Periods Ended December 31, 2017

Government Cash Management Fund

Average Annual Returns	1 Year	5 Years	10 Years
First Investors Life Series Government Cash Management Fund | First Investors Life Series Government Cash Management Fund	0.26%	0.05%	0.23%

XML

Label

Element

Value

First Investors Life Series Government Cash Management Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

First Investors Life Series Government Cash Management Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective:

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to earn a high rate of current income consistent with the preservation of capital and maintenance of liquidity.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund:

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund intends to operate as a “government money market fund” as defined in Rule 2a-7 under the Investment Company Act of 1940 as amended. The Fund will invest at least 99.5% of its total assets in (i) U.S. government securities; (ii) cash; and/or (iii) repurchase agreements that are collateralized fully by cash and/or U.S. government securities. In addition, under normal circumstances, the Fund will invest at least 80% of its net assets, including any borrowings for investment purposes, in U.S. government securities and repurchase agreements collateralized fully by cash or U.S. government securities.  U.S. government securities include: U.S. Treasury bills and notes; obligations issued by the U.S. government, its agencies or instrumentalities, including securities issued by entities chartered by Congress that are not issued or guaranteed by the U.S. Treasury, including the Federal National Mortgage Association, Federal Home Loan Mortgage Corporation, Federal Home Loan Banks and Federal Farm Credit Banks; and obligations issued by issuers that are guaranteed as to principal or interest by the U.S. government, its agencies or instrumentalities, including the Government National Mortgage Association.  The Fund may invest in fixed, variable and floating rate instruments.  The Fund generally invests in securities with remaining maturities of 397 days or less.

The Fund’s portfolio is managed to meet regulatory requirements that permit the Fund to maintain a stable net asset value (“NAV”) of $1.00 per share.  These include requirements relating to the credit quality, maturity, liquidity and diversification of the Fund’s investments.

Risk [Heading]

rr_RiskHeading

Principal Risks:

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You could lose money by investing in the Fund.  Although the Fund seeks to preserve a $1.00 per share net asset value, it cannot guarantee it will do so.  An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.  The Fund’s sponsor has no legal obligation to provide financial support to the Fund, and you should not expect that the sponsor will provide support to the Fund at any time.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Credit Risk.  The U.S. government securities the Fund invests in may or may not be backed by the full faith and credit of the U.S. government.  Securities issued by U.S. government sponsored enterprises are supported only by the credit of the issuing entity.  The value of an investment will decline if there is a default by or a deterioration in the credit quality of the issuer or a provider of a credit enhancement or demand feature.  This could cause the Fund's NAV to decline below $1.00 per share.

Interest Rate Risk.  Like the values of other debt instruments, the market values of U.S government securities are affected by changes in interest rates.  When interest rates rise, the market values of U.S. government securities generally decline.  This could cause the Fund’s NAV to decline below $1.00 per share.  Interest rates across the U.S. economy have recently increased and may continue to increase, thereby heightening the Fund’s exposure to the risks associated with rising interest rates.

Liquidity Risk.  Certain investments may be difficult or impossible to sell at a favorable time or price.  Market developments may cause the Fund’s investments to become less liquid and subject to erratic price movements, which may have an adverse effect on the Fund’s ability to maintain a $1.00 share price.

Market Risk.  The prices of the debt securities held by the Fund may decline in response to certain events, such as general economic and market conditions, adverse political or regulatory developments and interest rate fluctuations,.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions or cause the Fund’s NAV to decline below $1.00 per share.  Supply issues could arise within the U.S. Treasury securities market as demand increases for U.S. government securities.

Repurchase Agreement Risk.  If the seller in a repurchase agreement transaction defaults on its obligation to repurchase a security, the Fund may suffer delays, incur costs and lose money in exercising its rights.

Yield Risk.  The yields received by the Fund on its investments will generally decline as interest rates decline.

Although the Fund seeks to preserve the value of your investment at $1.00 per share, it is possible to lose money by investing in the Fund.

Risk Lose Money [Text]

rr_RiskLoseMoney

You could lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance:

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows the Fund’s average annual returns for 1, 5, and 10 years.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Prior to October 3, 2016, the Fund invested in certain securities that are no longer permissible for “government money market funds” under Rule 2a-7.  The performance below may have been different if the current limit on the Fund’s investments had been in effect.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the Fund.

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total Annual Returns For Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown, the highest quarterly return was 0.77% (for the quarter ended March 31, 2008) and the lowest quarterly return was 0.00% (for each quarter beginning with quarter ended December 31, 2009 through the quarter ended June 30, 2017).

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

The highest quarterly return was 0.77% (for the quarter ended March 31, 2008)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2008

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

0.77%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

The lowest quarterly return was 0.00% (for each quarter beginning with quarter ended December 31, 2009 through the quarter ended June 30, 2017)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2009

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

none

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns For Periods Ended December 31, 2017

Average Annual Return, Caption

rr_AverageAnnualReturnCaption

Government Cash Management Fund

First Investors Life Series Government Cash Management Fund | First Investors Life Series Government Cash Management Fund

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.75%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.44%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.19%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 121

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

378

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

654

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,443

Annual Return 2008

rr_AnnualReturn2008

2.03%

Annual Return 2009

rr_AnnualReturn2009

0.17%

Annual Return 2010

rr_AnnualReturn2010

none

Annual Return 2011

rr_AnnualReturn2011

none

Annual Return 2012

rr_AnnualReturn2012

none

Annual Return 2013

rr_AnnualReturn2013

none

Annual Return 2014

rr_AnnualReturn2014

none

Annual Return 2015

rr_AnnualReturn2015

none

Annual Return 2016

rr_AnnualReturn2016

none

Annual Return 2017

rr_AnnualReturn2017

0.26%

1 Year

rr_AverageAnnualReturnYear01

0.26%

5 Years

rr_AverageAnnualReturnYear05

0.05%

10 Years

rr_AverageAnnualReturnYear10

0.23%

XML

First Investors Life Series Growth & Income Fund

First Investors Life Series Growth & Income Fund

Investment Objective:

The Fund seeks long-term growth of capital and current 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 Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	First Investors Life Series Growth & Income Fund First Investors Life Series Growth & Income Fund
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	First Investors Life Series Growth & Income Fund First Investors Life Series Growth & Income Fund
Management Fees	0.73%
Distribution and Service (12b-1) Fees	none
Other Expenses	0.06%
Total Annual Fund Operating Expenses	0.79%

Example

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Expense Example	1 year	3 years	5 years	10 years
First Investors Life Series Growth & Income Fund | First Investors Life Series Growth & Income Fund | USD ($)	81	252	439	978

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 17% of the average value of its portfolio.

Principal Investment Strategies:

The Fund primarily invests in common stocks that offer the potential for capital growth, current income or both.  The Fund primarily invests in common stocks of large-size companies.  The Fund may also invest in mid- and small-size companies.  Some but not all of the companies the Fund invests in may regularly pay dividends.

The Fund generally uses a “bottom-up” approach to selecting investments. This means that the Fund generally identifies potential investments through fundamental research and analysis and thereafter focuses on other issues, such as economic trends, interest rates, industry diversification and market capitalization.  In deciding whether to buy or sell securities, the Fund considers, among other things, the issuer’s financial strength, management, earnings growth or potential earnings growth and the issuer’s valuation relative to its fundamentals and peers.

The Fund may sell a security if it becomes fully valued, is no longer attractively valued, its fundamentals have deteriorated or alternative investments become more attractive.

Principal Risks:

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Dividend Risk.  At times, the Fund may not be able to identify attractive dividend-paying stocks.  The income received by the Fund will also fluctuate due to the amount of dividends that companies elect to pay, which could adversely affect the Fund’s ability to pay dividends and its share price.

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  While dividend-paying stocks are generally considered less volatile than other stocks, there can be no guarantee that an investment therein will be less volatile than the general stock market.  The Fund’s investments in potential growth opportunities may increase the potential volatility of its share price.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with stocks of mid- and small-size companies is generally greater than that associated with stocks of larger, more established companies because stocks of mid- and small-size companies tend to experience sharper price fluctuations.  At times, it may be difficult to sell mid- to small-size company stocks at reasonable prices.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

Undervalued Securities Risk.  The Fund seeks to invest in securities that are undervalued and that will rise in value due to anticipated events or changes in investor perceptions.  If these developments do not occur, the market price of these securities may not rise as expected or may fall.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Performance:

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.

Total Annual Returns For Calendar Years Ended December 31

During the periods shown, the highest quarterly return was 17.42% (for the quarter ended June 30, 2009) and the lowest quarterly return was -22.33% (for the quarter ended December 31, 2008).

Average Annual Total Returns For Periods Ended December 31, 2017

Average Annual Returns - First Investors Life Series Growth & Income Fund		1 Year	5 Years	10 Years
First Investors Life Series Growth & Income Fund		18.28%	13.35%	8.05%
Russell 1000 Value Index (reflects no deduction for fees, expenses or taxes)	[1]	13.67%	14.04%	7.10%
S&P 500 Index (reflects no deduction for fees, expenses or taxes)		21.83%	15.79%	8.50%

[1] The Fund changed its primary broad-based securities index to the Russell 1000 Value Index from the S&P 500 Index as of March 14, 2018. The Fund elected to use the new index because it more closely reflects the Fund's investment strategies.

XML

Label

Element

Value

First Investors Life Series Growth & Income Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

First Investors Life Series Growth & Income Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective:

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term growth of capital and current income.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund:

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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 [Text Block]

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 17% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

17.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund primarily invests in common stocks that offer the potential for capital growth, current income or both.  The Fund primarily invests in common stocks of large-size companies.  The Fund may also invest in mid- and small-size companies.  Some but not all of the companies the Fund invests in may regularly pay dividends.

The Fund generally uses a “bottom-up” approach to selecting investments. This means that the Fund generally identifies potential investments through fundamental research and analysis and thereafter focuses on other issues, such as economic trends, interest rates, industry diversification and market capitalization.  In deciding whether to buy or sell securities, the Fund considers, among other things, the issuer’s financial strength, management, earnings growth or potential earnings growth and the issuer’s valuation relative to its fundamentals and peers.

The Fund may sell a security if it becomes fully valued, is no longer attractively valued, its fundamentals have deteriorated or alternative investments become more attractive.

Risk [Heading]

rr_RiskHeading

Principal Risks:

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Dividend Risk.  At times, the Fund may not be able to identify attractive dividend-paying stocks.  The income received by the Fund will also fluctuate due to the amount of dividends that companies elect to pay, which could adversely affect the Fund’s ability to pay dividends and its share price.

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  While dividend-paying stocks are generally considered less volatile than other stocks, there can be no guarantee that an investment therein will be less volatile than the general stock market.  The Fund’s investments in potential growth opportunities may increase the potential volatility of its share price.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with stocks of mid- and small-size companies is generally greater than that associated with stocks of larger, more established companies because stocks of mid- and small-size companies tend to experience sharper price fluctuations.  At times, it may be difficult to sell mid- to small-size company stocks at reasonable prices.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

Undervalued Securities Risk.  The Fund seeks to invest in securities that are undervalued and that will rise in value due to anticipated events or changes in investor perceptions.  If these developments do not occur, the market price of these securities may not rise as expected or may fall.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Risk Lose Money [Text]

rr_RiskLoseMoney

You can lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance:

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the Fund.

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total Annual Returns For Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown, the highest quarterly return was 17.42% (for the quarter ended June 30, 2009) and the lowest quarterly return was -22.33% (for the quarter ended December 31, 2008).

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

The highest quarterly return was 17.42% (for the quarter ended June 30, 2009)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

17.42%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

The lowest quarterly return was -22.33% (for the quarter ended December 31, 2008)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(22.33%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns For Periods Ended December 31, 2017

Performance Table Market Index Changed

rr_PerformanceTableMarketIndexChanged

The Fund changed its primary broad-based securities index to the Russell 1000 Value Index from the S&P 500 Index as of March 14, 2018. The Fund elected to use the new index because it more closely reflects the Fund’s investment strategies.

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

First Investors Life Series Growth & Income Fund | Russell 1000 Value Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

13.67%

^[1]

5 Years

rr_AverageAnnualReturnYear05

14.04%

^[1]

10 Years

rr_AverageAnnualReturnYear10

7.10%

^[1]

First Investors Life Series Growth & Income Fund | S&P 500 Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

21.83%

5 Years

rr_AverageAnnualReturnYear05

15.79%

10 Years

rr_AverageAnnualReturnYear10

8.50%

First Investors Life Series Growth & Income Fund | First Investors Life Series Growth & Income Fund

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.73%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.06%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.79%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 81

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

252

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

439

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 978

Annual Return 2008

rr_AnnualReturn2008

(35.22%)

Annual Return 2009

rr_AnnualReturn2009

28.05%

Annual Return 2010

rr_AnnualReturn2010

16.19%

Annual Return 2011

rr_AnnualReturn2011

2.37%

Annual Return 2012

rr_AnnualReturn2012

17.45%

Annual Return 2013

rr_AnnualReturn2013

38.06%

Annual Return 2014

rr_AnnualReturn2014

7.65%

Annual Return 2015

rr_AnnualReturn2015

(3.12%)

Annual Return 2016

rr_AnnualReturn2016

9.88%

Annual Return 2017

rr_AnnualReturn2017

18.28%

1 Year

rr_AverageAnnualReturnYear01

18.28%

5 Years

rr_AverageAnnualReturnYear05

13.35%

10 Years

rr_AverageAnnualReturnYear10

8.05%

[1] The Fund changed its primary broad-based securities index to the Russell 1000 Value Index from the S&P 500 Index as of March 14, 2018. The Fund elected to use the new index because it more closely reflects the Fund's investment strategies.

XML

First Investors Life Series International Fund

First Investors Life Series International Fund

Investment Objective:

The Fund primarily seeks long-term capital growth.

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 Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	First Investors Life Series International Fund First Investors Life Series International Fund
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	First Investors Life Series International Fund First Investors Life Series International Fund
Management Fees	0.75%
Distribution and Service (12b-1) Fees	none
Other Expenses	0.09%
Total Annual Fund Operating Expenses	0.84%

Example

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Expense Example	1 year	3 years	5 years	10 years
First Investors Life Series International Fund | First Investors Life Series International Fund | USD ($)	86	268	466	1,037

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 29% of the average value of its portfolio.

Principal Investment Strategies:

The Fund primarily invests in a portfolio of common stocks and other equity securities of companies that are located outside of the United States.  To a limited degree, the Fund may also invest in companies based in the United States.  The Fund primarily relies on the country where the issuer is incorporated, is headquartered or has its principal place of business in determining the location of an issuer. The Fund may consider a company to be located in a particular country even if it is not domiciled in, or have its principal place of business in, that country if at least 50% of its assets are in, or it expects to derive at least 50% of its total revenue or profits from, goods or services produced in or sales made in that country.

The Fund typically invests in the securities of medium to large size companies, but will also invest in smaller companies.  The Fund’s holdings may be limited to the securities of 40 to 60 different issuers and may focus its investments in companies located in or tied economically to particular countries or regions.  The Fund generally invests in securities that are traded in the foreign securities markets, though it may invest significantly in emerging or developing markets. Additionally, from time to time, in pursuing its investment strategies, the Fund may hold significant investments (25% or more of its assets) in a specific market sector, including the consumer staples sector.

The subadviser selects investments by screening a universe of stocks that meet its “quality growth” criteria, which include high return on equity and low to moderate leverage, among others.  It then further narrows that universe by using a bottom-up stock and business analysis approach to identify companies whose businesses are highly profitable, have consistent operating histories and financial performance and enjoy possible long-term economic prospects.  The subadviser also seeks to generate greater returns by investing in securities at a price below the company’s intrinsic worth.

In making sell decisions, the subadviser considers, among other things, whether a security’s price target has been met, whether there has been an overvaluation of the issuer by the market, whether there has been a clear deterioration of future earnings power and whether, in the subadviser’s opinion, there has been a loss of long-term competitive advantage.

Principal Risks:

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Emerging Markets Risk.  The risks of investing in foreign securities are heightened when investing in emerging or developing markets.  The economies and political environments of emerging or developing countries tend to be more unstable, resulting in more volatile rates of returns than developed markets and substantially greater risk.

Focused Portfolio Risk.  Because the Fund’s assets may be invested in a limited number of issuers, its performance may be more volatile than other funds whose portfolios contain a larger number of securities.

Foreign Securities Risk.  There are special risk factors associated with investing in foreign securities, including the risks of fluctuations in exchange rates, potential political and economic instability, differing accounting and financial reporting standards or inability to obtain reliable financial information regarding a company’s financial condition, less stringent regulation and supervision of foreign securities markets, custodians and securities depositories, and potential capital restrictions.  To the extent the Fund invests a significant portion of its assets in securities of a single country or region, it is more likely to be affected by events or conditions of that area.  As a result, it may be more volatile than a more geographically diversified fund.

Liquidity Risk.  Certain investments may be difficult or impossible to sell at a favorable time or price.  Market developments may cause the Fund’s investments to become less liquid and subject to erratic price movements.  This risk is particularly acute in the case of foreign securities that are traded in smaller, less-developed or emerging markets.

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with the securities of mid- and small-size companies is generally greater than that associated with securities of larger companies because such securities tend to experience sharper price fluctuations.  At times, it may be difficult for the Fund to sell mid- to small-size company stocks at reasonable prices.

Sector Risk.  The Fund may hold a significant amount of investments in similar businesses, which could be affected by the same economic or market conditions.  To the extent the Fund invests significantly in the consumer staples sector, the value of the Fund's shares may be particularly vulnerable to factors affecting that sector, such as the health of the overall economy, marketing campaigns, changes in consumer demands, government regulations and changes in commodity prices.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Performance:

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown. 

Total Annual Returns For Calendar Years Ended December 31

During the periods shown, the highest quarterly return was 19.05% (for the quarter ended June 30, 2009) and the lowest quarterly return was -19.25% (for the quarter ended September 30, 2008).

Average Annual Total Returns For Periods Ended December 31, 2017

Average Annual Returns - First Investors Life Series International Fund	1 Year	5 Years	10 Years
First Investors Life Series International Fund	32.96%	7.58%	3.60%
MSCI EAFE Index (Gross) (reflects no deduction for fees, expenses or taxes)	25.62%	8.39%	2.42%
MSCI EAFE Index (Net) (reflects the deduction of foreign withholding taxes on dividends)	25.03%	7.90%	1.94%

XML

Label

Element

Value

First Investors Life Series International Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

First Investors Life Series International Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective:

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund primarily seeks long-term capital growth.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund:

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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 [Text Block]

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 29% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

29.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund primarily invests in a portfolio of common stocks and other equity securities of companies that are located outside of the United States.  To a limited degree, the Fund may also invest in companies based in the United States.  The Fund primarily relies on the country where the issuer is incorporated, is headquartered or has its principal place of business in determining the location of an issuer. The Fund may consider a company to be located in a particular country even if it is not domiciled in, or have its principal place of business in, that country if at least 50% of its assets are in, or it expects to derive at least 50% of its total revenue or profits from, goods or services produced in or sales made in that country.

The Fund typically invests in the securities of medium to large size companies, but will also invest in smaller companies.  The Fund’s holdings may be limited to the securities of 40 to 60 different issuers and may focus its investments in companies located in or tied economically to particular countries or regions.  The Fund generally invests in securities that are traded in the foreign securities markets, though it may invest significantly in emerging or developing markets. Additionally, from time to time, in pursuing its investment strategies, the Fund may hold significant investments (25% or more of its assets) in a specific market sector, including the consumer staples sector.

The subadviser selects investments by screening a universe of stocks that meet its “quality growth” criteria, which include high return on equity and low to moderate leverage, among others.  It then further narrows that universe by using a bottom-up stock and business analysis approach to identify companies whose businesses are highly profitable, have consistent operating histories and financial performance and enjoy possible long-term economic prospects.  The subadviser also seeks to generate greater returns by investing in securities at a price below the company’s intrinsic worth.

In making sell decisions, the subadviser considers, among other things, whether a security’s price target has been met, whether there has been an overvaluation of the issuer by the market, whether there has been a clear deterioration of future earnings power and whether, in the subadviser’s opinion, there has been a loss of long-term competitive advantage.

Risk [Heading]

rr_RiskHeading

Principal Risks:

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Emerging Markets Risk.  The risks of investing in foreign securities are heightened when investing in emerging or developing markets.  The economies and political environments of emerging or developing countries tend to be more unstable, resulting in more volatile rates of returns than developed markets and substantially greater risk.

Focused Portfolio Risk.  Because the Fund’s assets may be invested in a limited number of issuers, its performance may be more volatile than other funds whose portfolios contain a larger number of securities.

Foreign Securities Risk.  There are special risk factors associated with investing in foreign securities, including the risks of fluctuations in exchange rates, potential political and economic instability, differing accounting and financial reporting standards or inability to obtain reliable financial information regarding a company’s financial condition, less stringent regulation and supervision of foreign securities markets, custodians and securities depositories, and potential capital restrictions.  To the extent the Fund invests a significant portion of its assets in securities of a single country or region, it is more likely to be affected by events or conditions of that area.  As a result, it may be more volatile than a more geographically diversified fund.

Liquidity Risk.  Certain investments may be difficult or impossible to sell at a favorable time or price.  Market developments may cause the Fund’s investments to become less liquid and subject to erratic price movements.  This risk is particularly acute in the case of foreign securities that are traded in smaller, less-developed or emerging markets.

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with the securities of mid- and small-size companies is generally greater than that associated with securities of larger companies because such securities tend to experience sharper price fluctuations.  At times, it may be difficult for the Fund to sell mid- to small-size company stocks at reasonable prices.

Sector Risk.  The Fund may hold a significant amount of investments in similar businesses, which could be affected by the same economic or market conditions.  To the extent the Fund invests significantly in the consumer staples sector, the value of the Fund's shares may be particularly vulnerable to factors affecting that sector, such as the health of the overall economy, marketing campaigns, changes in consumer demands, government regulations and changes in commodity prices.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Risk Lose Money [Text]

rr_RiskLoseMoney

You can lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance:

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown. 

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the Fund.

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total Annual Returns For Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown, the highest quarterly return was 19.05% (for the quarter ended June 30, 2009) and the lowest quarterly return was -19.25% (for the quarter ended September 30, 2008).

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

The highest quarterly return was 19.05% (for the quarter ended June 30, 2009)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

19.05%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

The lowest quarterly return was -19.25% (for the quarter ended September 30, 2008)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(19.25%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns For Periods Ended December 31, 2017

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

First Investors Life Series International Fund | MSCI EAFE Index (Gross) (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

25.62%

5 Years

rr_AverageAnnualReturnYear05

8.39%

10 Years

rr_AverageAnnualReturnYear10

2.42%

First Investors Life Series International Fund | MSCI EAFE Index (Net) (reflects the deduction of foreign withholding taxes on dividends)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

25.03%

5 Years

rr_AverageAnnualReturnYear05

7.90%

10 Years

rr_AverageAnnualReturnYear10

1.94%

First Investors Life Series International Fund | First Investors Life Series International Fund

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.75%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.09%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.84%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 86

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

268

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

466

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,037

Annual Return 2008

rr_AnnualReturn2008

(41.89%)

Annual Return 2009

rr_AnnualReturn2009

23.24%

Annual Return 2010

rr_AnnualReturn2010

13.45%

Annual Return 2011

rr_AnnualReturn2011

0.64%

Annual Return 2012

rr_AnnualReturn2012

20.85%

Annual Return 2013

rr_AnnualReturn2013

6.77%

Annual Return 2014

rr_AnnualReturn2014

2.39%

Annual Return 2015

rr_AnnualReturn2015

3.49%

Annual Return 2016

rr_AnnualReturn2016

(4.20%)

Annual Return 2017

rr_AnnualReturn2017

32.96%

1 Year

rr_AverageAnnualReturnYear01

32.96%

5 Years

rr_AverageAnnualReturnYear05

7.58%

10 Years

rr_AverageAnnualReturnYear10

3.60%

XML

First Investors Life Series Investment Grade Fund

First Investors Life Series Investment Grade Fund

Investment Objective:

The Fund seeks to generate a maximum level of income consistent with investment primarily in investment grade debt securities.

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 Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	First Investors Life Series Investment Grade Fund First Investors Life Series Investment Grade Fund
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	First Investors Life Series Investment Grade Fund First Investors Life Series Investment Grade Fund
Management Fees	0.75%
Distribution and Service (12b-1) Fees	none
Other Expenses	0.08%
Total Annual Fund Operating Expenses	0.83%

Example

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares ,your costs would be:

Expense Example	1 year	3 years	5 years	10 years
First Investors Life Series Investment Grade Fund | First Investors Life Series Investment Grade Fund | USD ($)	85	265	460	1,025

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 60% of the average value of its portfolio.

Principal Investment Strategies:

Under normal circumstances, the Fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in investment grade debt securities.  Investment grade debt securities include those that are rated within the four highest ratings categories by Moody’s Investors Service, Inc. (“Moody’s”) or S&P Global Ratings (“S&P”) or that are unrated but determined by the Fund’s investment adviser, Foresters Investment Management Company, Inc. (“Adviser”), to be of equivalent quality.

The Fund primarily invests in investment grade corporate bonds.  The Fund may also invest in other investment grade securities, including securities issued or guaranteed by the U.S. Government or U.S. Government-sponsored enterprises (some of which are not backed by the full faith and credit of the U.S. Government) and investment grade mortgage-backed and other asset-backed securities.  In making investment decisions, the Adviser considers the outlook for interest rates, economic forecasts and market conditions, credit ratings, and its own analysis of an issuer’s financial condition.  The Adviser will not necessarily sell an investment if its rating is reduced. 

To a lesser extent, the Fund also invests in high yield, below investment grade corporate bonds (commonly known as “high yield” or “junk bonds”).  The Adviser has retained Muzinich & Co, Inc. (“Muzinich”) as a subadvisor to manage this portion of the Fund.  High yield bonds include bonds that are rated below Baa3 by Moody’s or below BBB- by S&P as well as unrated bonds that are determined by Muzinich to be of equivalent quality.  Muzinich will consider ratings assigned by ratings agencies in selecting high yield bonds, but relies principally on its own research and investment analysis. In managing its portion of the Fund, Muzinich focuses on investments it believes can generate attractive and consistent income.  Muzinich may sell a bond when it shows deteriorating fundamentals or it falls short of the portfolio manager’s expectations.  In addition, the Adviser may also invest in exchange-traded funds (“ETFs”) that could expose the Fund to high yield securities.

The Fund may invest in securities of any maturity or duration, but may adjust its average portfolio weighted duration or maturity in anticipation of interest rate changes. For example, if the Fund expects interest rates to rise, it may seek to reduce its average portfolio weighted duration and maturity.  The Fund may also invest in U.S. Treasury futures and options on U.S. Treasury futures to hedge against changes in interest rates.

Additionally, from time to time, in pursuing its investment strategies, the Fund may hold significant investments (25% or more of its assets) in a specific market sector, including the financials sector.

Principal Risks:

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Credit Risk.  A debt issuer may become unable or unwilling to pay interest or principal when due.  The prices of debt securities are affected by the credit quality of the issuer and, in the case of mortgage-backed and asset-backed securities, the credit quality of the underlying loans.  Securities issued by U.S. Government-sponsored enterprises are supported only by the credit of the issuing entity.

Derivatives Risk.  Investments in U.S. Treasury futures and options on U.S. Treasury futures involve risks, such as potential losses if interest rates do not move as expected and the potential for greater losses than if these techniques had not been used.  Investments in derivatives can increase the volatility of the Fund’s share price and may expose it to significant additional costs.  Derivatives may be difficult to sell, unwind, or value.

Exchange-Traded Funds Risk.  The risks of investing in an ETF typically reflect the risks of the types of instruments in which the ETF invests. In addition, because ETFs are investment companies, the Fund will bear its proportionate share of the fees and expenses of an investment in an ETF. As a result, the Fund’s expenses may be higher and performance may be lower.

High Yield Securities Risk.  High yield debt securities (commonly known as “junk bonds”) have greater credit risk than higher quality debt securities because their issuers may not be as financially strong.  High yield securities are inherently speculative due to the risk associated with the issuer’s ability to make principal and interest payments.  During times of economic stress, high yield securities issuers may be unable to access credit to refinance their bonds or meet their credit obligations.

Interest Rate Risk.  In general, when interest rates rise, the market value of a debt security declines, and when interest rates decline, the market value of a debt security increases.  Interest rates across the U.S. economy have recently increased and may continue to increase, thereby heightening the Fund’s exposure to the risks associated with rising interest rates.  Securities with longer maturities and durations are generally more sensitive to interest rate changes.

Liquidity Risk.  Certain investments may be difficult or impossible to sell at a favorable time or price.  Market developments may cause the Fund’s investments to become less liquid and subject to erratic price movements.  High yield securities tend to be less liquid.

Market Risk.  The prices of the debt securities held by the Fund may decline in response to certain events, such as general economic and market conditions, adverse political or regulatory developments and interest rate fluctuations.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Prepayment and Extension Risk.  When interest rates decline, borrowers tend to refinance their loans and the loans that back mortgage-backed and other asset-backed securities suffer a higher rate of prepayment.  This could cause a decrease in the Fund’s income and share price.  Conversely, when interest rates rise, borrowers tend to repay their loans less quickly, which will generally increase the Fund’s sensitivity to interest rates and its potential for price declines.

Sector Risk.  The Fund may hold a significant amount of investments in similar businesses, which could be affected by the same economic or market conditions.  To the extent the Fund invests significantly in the financials sector, the value of the Fund's shares may be particularly vulnerable to factors affecting that sector, such as the availability and cost of capital, changes in interest rates, the rate of corporate and consumer debt defaults, credit ratings and quality, market liquidity, extensive government regulation and price competition.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Performance:

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.  Prior to May 1, 2018, Muzinich did not serve as a subadviser to the Fund.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown. 

Total Annual Returns For Calendar Years Ended December 31

During the periods shown, the highest quarterly return was 10.24% (for the quarter ended June 30, 2009) and the lowest quarterly return was -9.82% (for the quarter ended September 30, 2008).

Average Annual Total Returns For Periods Ended December 31, 2017

Average Annual Returns - First Investors Life Series Investment Grade Fund	1 Year	5 Years	10 Years
First Investors Life Series Investment Grade Fund	4.72%	2.78%	4.70%
BofA Merrill Lynch U.S. Corporate Master Index (reflects no deduction for fees, expenses or taxes)	6.47%	3.50%	5.59%

XML

Label

Element

Value

First Investors Life Series Investment Grade Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

First Investors Life Series Investment Grade Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective:

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to generate a maximum level of income consistent with investment primarily in investment grade debt securities.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund:

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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 [Text Block]

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 60% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

60.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares ,your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal circumstances, the Fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in investment grade debt securities.  Investment grade debt securities include those that are rated within the four highest ratings categories by Moody’s Investors Service, Inc. (“Moody’s”) or S&P Global Ratings (“S&P”) or that are unrated but determined by the Fund’s investment adviser, Foresters Investment Management Company, Inc. (“Adviser”), to be of equivalent quality.

The Fund primarily invests in investment grade corporate bonds.  The Fund may also invest in other investment grade securities, including securities issued or guaranteed by the U.S. Government or U.S. Government-sponsored enterprises (some of which are not backed by the full faith and credit of the U.S. Government) and investment grade mortgage-backed and other asset-backed securities.  In making investment decisions, the Adviser considers the outlook for interest rates, economic forecasts and market conditions, credit ratings, and its own analysis of an issuer’s financial condition.  The Adviser will not necessarily sell an investment if its rating is reduced. 

To a lesser extent, the Fund also invests in high yield, below investment grade corporate bonds (commonly known as “high yield” or “junk bonds”).  The Adviser has retained Muzinich & Co, Inc. (“Muzinich”) as a subadvisor to manage this portion of the Fund.  High yield bonds include bonds that are rated below Baa3 by Moody’s or below BBB- by S&P as well as unrated bonds that are determined by Muzinich to be of equivalent quality.  Muzinich will consider ratings assigned by ratings agencies in selecting high yield bonds, but relies principally on its own research and investment analysis. In managing its portion of the Fund, Muzinich focuses on investments it believes can generate attractive and consistent income.  Muzinich may sell a bond when it shows deteriorating fundamentals or it falls short of the portfolio manager’s expectations.  In addition, the Adviser may also invest in exchange-traded funds (“ETFs”) that could expose the Fund to high yield securities.

The Fund may invest in securities of any maturity or duration, but may adjust its average portfolio weighted duration or maturity in anticipation of interest rate changes. For example, if the Fund expects interest rates to rise, it may seek to reduce its average portfolio weighted duration and maturity.  The Fund may also invest in U.S. Treasury futures and options on U.S. Treasury futures to hedge against changes in interest rates.

Additionally, from time to time, in pursuing its investment strategies, the Fund may hold significant investments (25% or more of its assets) in a specific market sector, including the financials sector.

Risk [Heading]

rr_RiskHeading

Principal Risks:

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Credit Risk.  A debt issuer may become unable or unwilling to pay interest or principal when due.  The prices of debt securities are affected by the credit quality of the issuer and, in the case of mortgage-backed and asset-backed securities, the credit quality of the underlying loans.  Securities issued by U.S. Government-sponsored enterprises are supported only by the credit of the issuing entity.

Derivatives Risk.  Investments in U.S. Treasury futures and options on U.S. Treasury futures involve risks, such as potential losses if interest rates do not move as expected and the potential for greater losses than if these techniques had not been used.  Investments in derivatives can increase the volatility of the Fund’s share price and may expose it to significant additional costs.  Derivatives may be difficult to sell, unwind, or value.

Exchange-Traded Funds Risk.  The risks of investing in an ETF typically reflect the risks of the types of instruments in which the ETF invests. In addition, because ETFs are investment companies, the Fund will bear its proportionate share of the fees and expenses of an investment in an ETF. As a result, the Fund’s expenses may be higher and performance may be lower.

High Yield Securities Risk.  High yield debt securities (commonly known as “junk bonds”) have greater credit risk than higher quality debt securities because their issuers may not be as financially strong.  High yield securities are inherently speculative due to the risk associated with the issuer’s ability to make principal and interest payments.  During times of economic stress, high yield securities issuers may be unable to access credit to refinance their bonds or meet their credit obligations.

Interest Rate Risk.  In general, when interest rates rise, the market value of a debt security declines, and when interest rates decline, the market value of a debt security increases.  Interest rates across the U.S. economy have recently increased and may continue to increase, thereby heightening the Fund’s exposure to the risks associated with rising interest rates.  Securities with longer maturities and durations are generally more sensitive to interest rate changes.

Liquidity Risk.  Certain investments may be difficult or impossible to sell at a favorable time or price.  Market developments may cause the Fund’s investments to become less liquid and subject to erratic price movements.  High yield securities tend to be less liquid.

Market Risk.  The prices of the debt securities held by the Fund may decline in response to certain events, such as general economic and market conditions, adverse political or regulatory developments and interest rate fluctuations.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Prepayment and Extension Risk.  When interest rates decline, borrowers tend to refinance their loans and the loans that back mortgage-backed and other asset-backed securities suffer a higher rate of prepayment.  This could cause a decrease in the Fund’s income and share price.  Conversely, when interest rates rise, borrowers tend to repay their loans less quickly, which will generally increase the Fund’s sensitivity to interest rates and its potential for price declines.

Sector Risk.  The Fund may hold a significant amount of investments in similar businesses, which could be affected by the same economic or market conditions.  To the extent the Fund invests significantly in the financials sector, the value of the Fund's shares may be particularly vulnerable to factors affecting that sector, such as the availability and cost of capital, changes in interest rates, the rate of corporate and consumer debt defaults, credit ratings and quality, market liquidity, extensive government regulation and price competition.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Risk Lose Money [Text]

rr_RiskLoseMoney

You can lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance:

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.  Prior to May 1, 2018, Muzinich did not serve as a subadviser to the Fund.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown. 

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the Fund.

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total Annual Returns For Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown, the highest quarterly return was 10.24% (for the quarter ended June 30, 2009) and the lowest quarterly return was -9.82% (for the quarter ended September 30, 2008).

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

The highest quarterly return was 10.24% (for the quarter ended June 30, 2009)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

10.24%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

The lowest quarterly return was -9.82% (for the quarter ended September 30, 2008)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(9.82%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns For Periods Ended December 31, 2017

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

First Investors Life Series Investment Grade Fund | BofA Merrill Lynch U.S. Corporate Master Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

6.47%

5 Years

rr_AverageAnnualReturnYear05

3.50%

10 Years

rr_AverageAnnualReturnYear10

5.59%

First Investors Life Series Investment Grade Fund | First Investors Life Series Investment Grade Fund

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.75%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.08%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.83%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 85

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

265

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

460

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,025

Annual Return 2008

rr_AnnualReturn2008

(11.60%)

Annual Return 2009

rr_AnnualReturn2009

20.94%

Annual Return 2010

rr_AnnualReturn2010

9.26%

Annual Return 2011

rr_AnnualReturn2011

6.23%

Annual Return 2012

rr_AnnualReturn2012

11.23%

Annual Return 2013

rr_AnnualReturn2013

(0.80%)

Annual Return 2014

rr_AnnualReturn2014

5.86%

Annual Return 2015

rr_AnnualReturn2015

(0.35%)

Annual Return 2016

rr_AnnualReturn2016

4.65%

Annual Return 2017

rr_AnnualReturn2017

4.72%

1 Year

rr_AverageAnnualReturnYear01

4.72%

5 Years

rr_AverageAnnualReturnYear05

2.78%

10 Years

rr_AverageAnnualReturnYear10

4.70%

XML

First Investors Life Series Limited Duration Bond Fund

First Investors Life Series Limited Duration Bond Fund

Investment Objective:

The Fund seeks current income consistent with low volatility of principal.

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 Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	First Investors Life Series Limited Duration Bond Fund First Investors Life Series Limited Duration Bond Fund
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	First Investors Life Series Limited Duration Bond Fund First Investors Life Series Limited Duration Bond Fund
Management Fees	0.75%
Distribution and Service (12b-1) Fees	none
Other Expenses	0.41%
Total Annual Fund Operating Expenses	1.16%

Example

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Expense Example	1 year	3 years	5 years	10 years
First Investors Life Series Limited Duration Bond Fund | First Investors Life Series Limited Duration Bond Fund | USD ($)	118	368	638	1,409

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 82% of the average value of its portfolio.

Principal Investment Strategies:

Under normal circumstances, the Fund will invest at least 80% of its net assets (plus any borrowings for investment purposes) in investment grade bonds.  For purposes of this 80% policy, investment grade bonds also include other investment grade fixed-income securities.

Investment grade debt securities include those that are rated within the four highest ratings categories by Moody's Investors Service, Inc. (“Moody's”) or S&P Global Ratings (“S&P”) or that are unrated but determined by the Fund's investment adviser, Foresters Investment Management Company, Inc. (“Adviser”), to be of equivalent quality.

The Fund may invest in a variety of different types of investment grade securities, including corporate bonds, securities issued or guaranteed by the U.S. Government or U.S. Government-sponsored enterprises (some of which are not backed by the full faith and credit of the U.S. Government), mortgage-backed and other asset-backed securities.  In making investment decisions, the Adviser considers the outlook for interest rates, economic forecasts and market conditions, credit ratings, and its own analysis of an issuer's financial condition.  The Adviser will not necessarily sell an investment if its rating is reduced. 

To a lesser extent, the Fund also invests in high yield, below investment grade corporate bonds (commonly known as “high yield” or “junk bonds”).  The Adviser has retained Muzinich & Co, Inc. (“Muzinich”) as a subadviser to manage this portion of the Fund. High yield bonds include bonds that are rated below Baa3 by Moody’s or below BBB- by S&P as well as unrated bonds that are determined by Muzinich to be of equivalent quality.  Muzinich will consider ratings assigned by ratings agencies in selecting high yield bonds, but relies principally on its own research and investment analysis. In managing its portion of the Fund, Muzinich focuses on investments it believes can generate attractive and consistent income.  Muzinich may sell a bond when it shows deteriorating fundamentals or it falls short of the portfolio manager’s expectations.  In addition, the Adviser may also invest in exchange-traded funds (“ETFs”) that could expose the Fund to high yield securities.

Additionally, from time to time, in pursuing its investment strategies, the Fund may hold significant investments (25% or more of its assets) in a specific market sector, including the financials sector.

The Fund seeks to maintain an average weighted duration of between one and six years.  Duration is a measurement of a bond’s sensitivity to changes in interest rates.  For every 1% change in interest rates, a bond’s price generally changes approximately 1% in the opposite direction for each year of duration.  For example, if a portfolio of fixed income securities has an average weighted duration of six years, its value can be expected to fall about 6% if interest rates rise by 1%.  Conversely, the portfolio's value can be expected to rise approximately 6% if interest rates fall by 1%.  As a result, prices of securities with longer durations tend to be more sensitive to interest rate changes than prices of securities with shorter durations.  By comparison, a debt security's “maturity” is the date on which the security matures and the issuer is obligated to repay principal.  Duration is typically not equal to maturity.

The Fund may invest in U.S. Treasury futures and options on U.S. Treasury futures to hedge against changes in interest rates.

Principal Risks:

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Credit Risk.  A debt issuer may become unable or unwilling to pay interest or principal when due.  The prices of debt securities are affected by the credit quality of the issuer and, in the case of mortgage-backed and asset-backed securities, the credit quality of the underlying loans.  Securities issued by U.S. Government-sponsored enterprises are supported only by the credit of the issuing entity.

Derivatives Risk.  Investments in U.S. Treasury futures and options on U.S. Treasury futures to hedge against changes in interest rates involve risks, such as potential losses if interest rates do not move as expected and the potential for greater losses than if these techniques had not been used.  Investments in derivatives can increase the volatility of the Fund's share price and may expose it to significant additional costs.  Derivatives may be difficult to sell, unwind, or value.

Exchange-Traded Funds Risk.  The risks of investing in an ETF typically reflect the risks of the types of instruments in which the ETF invests. In addition, because ETFs are investment companies, the Fund will bear its proportionate share of the fees and expenses of an investment in an ETF. As a result, the Fund’s expenses may be higher and performance may be lower.

High Yield Securities Risk.  High yield debt securities (commonly known as “junk bonds”) have greater credit risk than higher quality debt securities because their issuers may not be as financially strong.  High yield securities are inherently speculative due to the risk associated with the issuer’s ability to make principal and interest payments.  During times of economic stress, high yield securities issuers may be unable to access credit to refinance their bonds or meet their credit obligations.

Interest Rate Risk.  In general, when interest rates rise, the market value of a debt security declines, and when interest rates decline, the market value of a debt security increases.  Interest rates across the U.S. economy have recently increased and may continue to increase, thereby heightening the Fund’s exposure to the risks associated with rising interest rates.  Securities with longer maturities and durations are generally more sensitive to interest rate changes.

Market Risk.  The prices of the debt securities held by the Fund may decline in response to certain events, such as general economic and market conditions, adverse political or regulatory developments and interest rate fluctuations.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.  Certain investments may be difficult or impossible to sell at a favorable time or price when the Fund requires liquidity to make redemptions.

Prepayment and Extension Risk.  When interest rates decline, borrowers tend to refinance their loans and the loans that back mortgage-backed and other asset-backed securities suffer a higher rate of prepayment.  This could cause a decrease in the Fund's income and share price.  Conversely, when interest rates rise, borrowers tend to repay their loans less quickly which, will generally increase both the Fund's sensitivity to interest rates and its potential for price declines.

Sector Risk.  The Fund may hold a significant amount of investments in similar businesses, which could be affected by the same economic or market conditions.  To the extent the Fund invests significantly in the financials sector, the value of the Fund's shares may be particularly vulnerable to factors affecting that sector, such as the availability and cost of capital, changes in interest rates, the rate of corporate and consumer debt defaults, credit ratings and quality, market liquidity, extensive government regulation and price competition.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Performance:

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for the 1-year and Life of Fund periods compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.  Prior to May 1, 2018, Muzinich did not serve as a subadviser to the Fund.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.

Total Annual Returns For Calendar Years Ended December 31

During the periods shown, the highest quarterly return was 1.16% (for the quarter ended March 31, 2016) and the lowest quarterly return was -1.23% (for the quarter ended December 31, 2016).

Average Annual Total Returns For Periods Ended December 31, 2017

Average Annual Returns - First Investors Life Series Limited Duration Bond Fund	1 Year	Life of Fund
First Investors Life Series Limited Duration Bond Fund (Inception Date: 7/1/14)	1.26%	(0.36%)
BofA Merrill Lynch 1-5 Year U.S. Broad Market Index (reflects no deduction for fees, expenses or taxes)	1.33%	1.27%

XML

Label

Element

Value

First Investors Life Series Limited Duration Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

First Investors Life Series Limited Duration Bond Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective:

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks current income consistent with low volatility of principal.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund:

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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 [Text Block]

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 82% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

82.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal circumstances, the Fund will invest at least 80% of its net assets (plus any borrowings for investment purposes) in investment grade bonds.  For purposes of this 80% policy, investment grade bonds also include other investment grade fixed-income securities.

Investment grade debt securities include those that are rated within the four highest ratings categories by Moody's Investors Service, Inc. (“Moody's”) or S&P Global Ratings (“S&P”) or that are unrated but determined by the Fund's investment adviser, Foresters Investment Management Company, Inc. (“Adviser”), to be of equivalent quality.

The Fund may invest in a variety of different types of investment grade securities, including corporate bonds, securities issued or guaranteed by the U.S. Government or U.S. Government-sponsored enterprises (some of which are not backed by the full faith and credit of the U.S. Government), mortgage-backed and other asset-backed securities.  In making investment decisions, the Adviser considers the outlook for interest rates, economic forecasts and market conditions, credit ratings, and its own analysis of an issuer's financial condition.  The Adviser will not necessarily sell an investment if its rating is reduced. 

To a lesser extent, the Fund also invests in high yield, below investment grade corporate bonds (commonly known as “high yield” or “junk bonds”).  The Adviser has retained Muzinich & Co, Inc. (“Muzinich”) as a subadviser to manage this portion of the Fund. High yield bonds include bonds that are rated below Baa3 by Moody’s or below BBB- by S&P as well as unrated bonds that are determined by Muzinich to be of equivalent quality.  Muzinich will consider ratings assigned by ratings agencies in selecting high yield bonds, but relies principally on its own research and investment analysis. In managing its portion of the Fund, Muzinich focuses on investments it believes can generate attractive and consistent income.  Muzinich may sell a bond when it shows deteriorating fundamentals or it falls short of the portfolio manager’s expectations.  In addition, the Adviser may also invest in exchange-traded funds (“ETFs”) that could expose the Fund to high yield securities.

Additionally, from time to time, in pursuing its investment strategies, the Fund may hold significant investments (25% or more of its assets) in a specific market sector, including the financials sector.

The Fund seeks to maintain an average weighted duration of between one and six years.  Duration is a measurement of a bond’s sensitivity to changes in interest rates.  For every 1% change in interest rates, a bond’s price generally changes approximately 1% in the opposite direction for each year of duration.  For example, if a portfolio of fixed income securities has an average weighted duration of six years, its value can be expected to fall about 6% if interest rates rise by 1%.  Conversely, the portfolio's value can be expected to rise approximately 6% if interest rates fall by 1%.  As a result, prices of securities with longer durations tend to be more sensitive to interest rate changes than prices of securities with shorter durations.  By comparison, a debt security's “maturity” is the date on which the security matures and the issuer is obligated to repay principal.  Duration is typically not equal to maturity.

The Fund may invest in U.S. Treasury futures and options on U.S. Treasury futures to hedge against changes in interest rates.

Risk [Heading]

rr_RiskHeading

Principal Risks:

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Credit Risk.  A debt issuer may become unable or unwilling to pay interest or principal when due.  The prices of debt securities are affected by the credit quality of the issuer and, in the case of mortgage-backed and asset-backed securities, the credit quality of the underlying loans.  Securities issued by U.S. Government-sponsored enterprises are supported only by the credit of the issuing entity.

Derivatives Risk.  Investments in U.S. Treasury futures and options on U.S. Treasury futures to hedge against changes in interest rates involve risks, such as potential losses if interest rates do not move as expected and the potential for greater losses than if these techniques had not been used.  Investments in derivatives can increase the volatility of the Fund's share price and may expose it to significant additional costs.  Derivatives may be difficult to sell, unwind, or value.

Exchange-Traded Funds Risk.  The risks of investing in an ETF typically reflect the risks of the types of instruments in which the ETF invests. In addition, because ETFs are investment companies, the Fund will bear its proportionate share of the fees and expenses of an investment in an ETF. As a result, the Fund’s expenses may be higher and performance may be lower.

High Yield Securities Risk.  High yield debt securities (commonly known as “junk bonds”) have greater credit risk than higher quality debt securities because their issuers may not be as financially strong.  High yield securities are inherently speculative due to the risk associated with the issuer’s ability to make principal and interest payments.  During times of economic stress, high yield securities issuers may be unable to access credit to refinance their bonds or meet their credit obligations.

Interest Rate Risk.  In general, when interest rates rise, the market value of a debt security declines, and when interest rates decline, the market value of a debt security increases.  Interest rates across the U.S. economy have recently increased and may continue to increase, thereby heightening the Fund’s exposure to the risks associated with rising interest rates.  Securities with longer maturities and durations are generally more sensitive to interest rate changes.

Market Risk.  The prices of the debt securities held by the Fund may decline in response to certain events, such as general economic and market conditions, adverse political or regulatory developments and interest rate fluctuations.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.  Certain investments may be difficult or impossible to sell at a favorable time or price when the Fund requires liquidity to make redemptions.

Prepayment and Extension Risk.  When interest rates decline, borrowers tend to refinance their loans and the loans that back mortgage-backed and other asset-backed securities suffer a higher rate of prepayment.  This could cause a decrease in the Fund's income and share price.  Conversely, when interest rates rise, borrowers tend to repay their loans less quickly which, will generally increase both the Fund's sensitivity to interest rates and its potential for price declines.

Sector Risk.  The Fund may hold a significant amount of investments in similar businesses, which could be affected by the same economic or market conditions.  To the extent the Fund invests significantly in the financials sector, the value of the Fund's shares may be particularly vulnerable to factors affecting that sector, such as the availability and cost of capital, changes in interest rates, the rate of corporate and consumer debt defaults, credit ratings and quality, market liquidity, extensive government regulation and price competition.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Risk Lose Money [Text]

rr_RiskLoseMoney

You can lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance:

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for the 1-year and Life of Fund periods compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.  Prior to May 1, 2018, Muzinich did not serve as a subadviser to the Fund.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the Fund.

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total Annual Returns For Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown, the highest quarterly return was 1.16% (for the quarter ended March 31, 2016) and the lowest quarterly return was -1.23% (for the quarter ended December 31, 2016).

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

The highest quarterly return was 1.16% (for the quarter ended March 31, 2016)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2016

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

1.16%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

The lowest quarterly return was -1.23% (for the quarter ended December 31, 2016)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2016

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(1.23%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns For Periods Ended December 31, 2017

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

First Investors Life Series Limited Duration Bond Fund | BofA Merrill Lynch 1-5 Year U.S. Broad Market Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

1.33%

Life of Fund

rr_AverageAnnualReturnSinceInception

1.27%

First Investors Life Series Limited Duration Bond Fund | First Investors Life Series Limited Duration Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.75%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.41%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.16%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 118

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

368

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

638

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,409

Annual Return 2015

rr_AnnualReturn2015

(0.51%)

Annual Return 2016

rr_AnnualReturn2016

0.64%

Annual Return 2017

rr_AnnualReturn2017

1.26%

1 Year

rr_AverageAnnualReturnYear01

1.26%

Life of Fund

rr_AverageAnnualReturnSinceInception

(0.36%)

Inception Date

rr_AverageAnnualReturnInceptionDate

Jul. 01, 2014

XML

First Investors Life Series Opportunity Fund

First Investors Life Series Opportunity Fund

Investment Objective:

The Fund seeks long-term capital growth.

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 Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	First Investors Life Series Opportunity Fund First Investors Life Series Opportunity Fund
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	First Investors Life Series Opportunity Fund First Investors Life Series Opportunity Fund
Management Fees	0.75%
Distribution and Service (12b-1) Fees	none
Other Expenses	0.09%
Acquired Fund Fees and Expenses	0.01%
Total Annual Fund Operating Expenses	0.85%

Example

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Expense Example	1 year	3 years	5 years	10 years
First Investors Life Series Opportunity Fund | First Investors Life Series Opportunity Fund | USD ($)	87	271	471	1,049

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 30% of the average value of its portfolio.

Principal Investment Strategies:

The Fund invests primarily in mid- and small-size companies that the Fund’s investment adviser, Foresters Investment Management Company, Inc., believes offer strong growth opportunities.  The Fund may also invest in exchange-traded funds (“ETFs”) to gain exposure to such securities.  The Fund may continue to hold stocks of companies that grow into larger companies and may also invest opportunistically in larger companies.

The Fund uses a “bottom-up” approach to selecting investments.  The Fund uses fundamental research to search for companies that have one or more of the following: a strong balance sheet; experienced management; above-average earnings growth potential; and stocks that are attractively priced.  The Fund attempts to stay broadly diversified, but it may emphasize certain industry sectors based upon economic and market conditions.

The Fund may sell a stock if it becomes fully valued, its fundamentals have deteriorated or alternative investments become more attractive.  The Fund may also sell a stock if it grows into a large, well-established company, although it may also continue to hold such a stock irrespective of its size.

Principal Risks:

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Exchange-Traded Funds Risk.  The risks of investing in an ETF typically reflect the risks of the instruments in which the ETF invests. In addition, because ETFs are investment companies, the Fund will bear its proportionate share of the fees and expenses of an investment in an ETF. As a result, the Fund’s expenses may be higher and performance may be lower.

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with stocks of mid- and small-size companies is generally greater than that associated with stocks of larger, more established companies because stocks of mid- and small-size companies tend to experience sharper price fluctuations.  At times, it may be difficult to sell mid- to small-size company stocks at reasonable prices.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Performance:

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for the 1-year, 5-year and Life of Fund periods compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown. 

Total Annual Returns For Calendar Years Ended December 31

During the periods shown, the highest quarterly return was 11.93% (for the quarter ended March 31, 2013) and the lowest quarterly return was -9.65% (for the quarter ended September 30, 2015).

Average Annual Total Returns For Periods Ended December 31, 2017

Average Annual Returns - First Investors Life Series Opportunity Fund	1 Year	5 Years	Life of Fund
First Investors Life Series Opportunity Fund (Inception Date: 12/17/12)	19.00%	13.59%	13.61%
S&P Mid-Cap 400 Index (reflects no deduction for fees, expenses or taxes)	16.24%	15.01%	15.11%

XML

Label

Element

Value

First Investors Life Series Opportunity Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

First Investors Life Series Opportunity Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective:

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term capital growth.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund:

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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 [Text Block]

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 30% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

30.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund invests primarily in mid- and small-size companies that the Fund’s investment adviser, Foresters Investment Management Company, Inc., believes offer strong growth opportunities.  The Fund may also invest in exchange-traded funds (“ETFs”) to gain exposure to such securities.  The Fund may continue to hold stocks of companies that grow into larger companies and may also invest opportunistically in larger companies.

The Fund uses a “bottom-up” approach to selecting investments.  The Fund uses fundamental research to search for companies that have one or more of the following: a strong balance sheet; experienced management; above-average earnings growth potential; and stocks that are attractively priced.  The Fund attempts to stay broadly diversified, but it may emphasize certain industry sectors based upon economic and market conditions.

The Fund may sell a stock if it becomes fully valued, its fundamentals have deteriorated or alternative investments become more attractive.  The Fund may also sell a stock if it grows into a large, well-established company, although it may also continue to hold such a stock irrespective of its size.

Risk [Heading]

rr_RiskHeading

Principal Risks:

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Exchange-Traded Funds Risk.  The risks of investing in an ETF typically reflect the risks of the instruments in which the ETF invests. In addition, because ETFs are investment companies, the Fund will bear its proportionate share of the fees and expenses of an investment in an ETF. As a result, the Fund’s expenses may be higher and performance may be lower.

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with stocks of mid- and small-size companies is generally greater than that associated with stocks of larger, more established companies because stocks of mid- and small-size companies tend to experience sharper price fluctuations.  At times, it may be difficult to sell mid- to small-size company stocks at reasonable prices.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Risk Lose Money [Text]

rr_RiskLoseMoney

You can lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance:

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for the 1-year, 5-year and Life of Fund periods compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown. 

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the Fund.

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total Annual Returns For Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown, the highest quarterly return was 11.93% (for the quarter ended March 31, 2013) and the lowest quarterly return was -9.65% (for the quarter ended September 30, 2015).

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

The highest quarterly return was 11.93% (for the quarter ended March 31, 2013)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2013

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

11.93%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

The lowest quarterly return was -9.65% (for the quarter ended September 30, 2015)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(9.65%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns For Periods Ended December 31, 2017

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

First Investors Life Series Opportunity Fund | S&P Mid-Cap 400 Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

16.24%

5 Years

rr_AverageAnnualReturnYear05

15.01%

Life of Fund

rr_AverageAnnualReturnSinceInception

15.11%

First Investors Life Series Opportunity Fund | First Investors Life Series Opportunity Fund

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.75%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.09%

Acquired Fund Fees and Expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.01%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.85%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 87

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

271

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

471

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,049

Annual Return 2013

rr_AnnualReturn2013

39.96%

Annual Return 2014

rr_AnnualReturn2014

5.73%

Annual Return 2015

rr_AnnualReturn2015

(0.81%)

Annual Return 2016

rr_AnnualReturn2016

8.26%

Annual Return 2017

rr_AnnualReturn2017

19.00%

1 Year

rr_AverageAnnualReturnYear01

19.00%

5 Years

rr_AverageAnnualReturnYear05

13.59%

Life of Fund

rr_AverageAnnualReturnSinceInception

13.61%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 17, 2012

XML

First Investors Life Series Real Estate Fund

First Investors Life Series Real Estate Fund

Investment Objective:

The Fund seeks total return.

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 Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	First Investors Life Series Real Estate Fund First Investors Life Series Real Estate Fund
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	First Investors Life Series Real Estate Fund First Investors Life Series Real Estate Fund
Management Fees	0.75%
Distribution and Service (12b-1) Fees	none
Other Expenses	0.36%
Total Annual Fund Operating Expenses	1.11%

Example

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Expense Example	1 year	3 years	5 years	10 years
First Investors Life Series Real Estate Fund | First Investors Life Series Real Estate Fund | USD ($)	113	353	612	1,352

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 43% of the average value of its portfolio.

Principal Investment Strategies:

Under normal circumstances, the Fund will invest at least 80% of its net assets (plus any borrowings for investment purposes) in common stocks and other equity securities of companies principally engaged in the real estate industry and/or investments that provide exposure to such companies.  For purposes of this 80% policy, other equity securities may include, without limitation, preferred stock, equity-based exchange-traded funds (“ETFs”) and instruments that are convertible into common stock.

The Fund will normally invest its assets primarily in securities issued by real estate investment trusts (“REITs”) listed on a U.S. stock exchange.  Currently, the only REITs the Fund intends to invest in are U.S. exchange-listed REITs.  The Fund typically will invest in equity REITs (i.e., REITs that directly own real estate), mortgage REITs (i.e., REITs that lend money directly to real estate owners and/or operators or invest in long-term mortgage pools) and/or hybrid REITs (i.e., REITs that participate in both equity and mortgage investing). 

The Fund may, to a lesser extent, invest in securities of other companies principally engaged in the real estate industry.  An issuer is principally “engaged in” the real estate industry if at least 50% of its assets, gross income or net profits is attributable to the ownership, construction, management or sale of residential, commercial or industrial real estate, or to products or services related to the real estate industry.  The Fund may invest in REITs and real estate companies of any market capitalization.

The Fund generally uses a “bottom-up” approach in selecting investments that entails performing fundamental analyses to identify securities that the Fund’s adviser believes can achieve superior returns, with a focus on companies with high, consistent return on invested capital, recurring operating income and strong capital structure.  The Fund will generally consider investments that meet one or more of the following criteria: discount to intrinsic value, attractive valuation relative to industry peers or the presence of a potential stock-specific catalyst. 

The Fund may sell a security if it becomes fully valued, its fundamentals have deteriorated or alternative investment opportunities become more attractive.

The Fund will concentrate its investments in the real estate industry.  The Fund is non-diversified.

Principal Risks:

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Industry Concentration Risk. The Fund’s strategy of concentrating its investments in issuers engaged in the real estate industry means that the Fund’s performance will be closely tied to the performance of that market segment.  The Fund will be more susceptible to adverse economic, market, political or regulatory occurrences affecting the real estate industry than a less concentrated fund.

Interest Rate Risk.  In general, when interest rates rise, the market values of real estate and real estate companies decline.  Interest rates across the U.S. economy have recently increased and may continue to increase, thereby heightening the Fund’s exposure to the risks associated with rising interest rates.

Liquidity Risk.  Certain investments may be difficult or impossible to sell at a favorable time or price.  Market developments may cause the Fund’s investments to become less liquid and subject to erratic price movements.  Liquidity risk is heightened for real estate companies and REITs with smaller market capitalizations, limited investments, larger amounts of debt, or higher levels of exposure to sub-prime mortgages.

Market Risk.  The prices of equity securities, including securities issued by REITs,  may decline or experience volatility over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with securities of mid- and small-size companies is generally greater than that associated with securities of larger, more established issuers because securities of mid- and small-size issuers tend to experience sharper price fluctuations.  At times, it may be difficult to sell securities of mid-to-small-size issuers at reasonable prices.

Non-Diversification Risk.  The Fund is non-diversified and, as such, its assets may be invested in a limited number of issuers. This means that the Fund’s performance may be substantially impacted by the change in value of even a single holding.

Prepayment and Extension Risk.  When interest rates decline, borrowers tend to refinance their mortgages.  When this occurs, mortgages may suffer a higher rate of prepayment and a mortgage or hybrid REIT’s income and share price may decline.  Conversely, when interest rates rise, borrowers tend to repay their mortgages less quickly, which generally increases a mortgage or hybrid REIT’s sensitivity to interest rates and its potential for price declines.

Real Estate Investments Risk.  The Fund is subject to the risks related to investments in real estate,  including declines in the real estate market, decreases in property revenues, increases in interest rates, increases in property taxes and operating expenses, legal and regulatory changes, a lack of credit or capital, defaults by borrowers or tenants, environmental problems and natural disasters.

REIT Risk.  In addition to the risks associated with the real estate industry, REITs are subject to additional risks, including those related to adverse governmental actions, declines in property value, and the potential failure to qualify for federal tax-free “pass-through” of distributed net income and net realized gains and exemption from registration as an investment company. REITs are dependent upon specialized management skills and may invest in relatively few properties, a small geographic area or a small number of property types.  As a result, investments in REITs may be volatile.  REITs are pooled investment vehicles with their own fees and expenses and the Fund will indirectly bear a proportionate share of those fees and expenses.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Performance:

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for the 1-year and Life of Fund periods compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.

Total Annual Returns For Calendar Years Ended December 31

During the periods shown, the highest quarterly return was 6.67% (for the quarter ended March 31, 2016) and the lowest quarterly return was -2.64% (for the quarter ended September 30, 2017).

Average Annual Total Returns For Periods Ended December 31, 2017

Average Annual Returns - First Investors Life Series Real Estate Fund	1 Year	Life of Fund
First Investors Life Series Real Estate Fund (Inception Date: 5/1/15)	1.27%	3.47%
Dow Jones U.S. Select REIT Index (reflects no deduction for fees, expenses or taxes)	3.76%	6.13%

XML

Label

Element

Value

First Investors Life Series Real Estate Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

First Investors Life Series Real Estate Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective:

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks total return.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund:

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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 [Text Block]

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 43% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

43.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal circumstances, the Fund will invest at least 80% of its net assets (plus any borrowings for investment purposes) in common stocks and other equity securities of companies principally engaged in the real estate industry and/or investments that provide exposure to such companies.  For purposes of this 80% policy, other equity securities may include, without limitation, preferred stock, equity-based exchange-traded funds (“ETFs”) and instruments that are convertible into common stock.

The Fund will normally invest its assets primarily in securities issued by real estate investment trusts (“REITs”) listed on a U.S. stock exchange.  Currently, the only REITs the Fund intends to invest in are U.S. exchange-listed REITs.  The Fund typically will invest in equity REITs (i.e., REITs that directly own real estate), mortgage REITs (i.e., REITs that lend money directly to real estate owners and/or operators or invest in long-term mortgage pools) and/or hybrid REITs (i.e., REITs that participate in both equity and mortgage investing). 

The Fund may, to a lesser extent, invest in securities of other companies principally engaged in the real estate industry.  An issuer is principally “engaged in” the real estate industry if at least 50% of its assets, gross income or net profits is attributable to the ownership, construction, management or sale of residential, commercial or industrial real estate, or to products or services related to the real estate industry.  The Fund may invest in REITs and real estate companies of any market capitalization.

The Fund generally uses a “bottom-up” approach in selecting investments that entails performing fundamental analyses to identify securities that the Fund’s adviser believes can achieve superior returns, with a focus on companies with high, consistent return on invested capital, recurring operating income and strong capital structure.  The Fund will generally consider investments that meet one or more of the following criteria: discount to intrinsic value, attractive valuation relative to industry peers or the presence of a potential stock-specific catalyst. 

The Fund may sell a security if it becomes fully valued, its fundamentals have deteriorated or alternative investment opportunities become more attractive.

The Fund will concentrate its investments in the real estate industry.  The Fund is non-diversified.

Strategy Portfolio Concentration [Text]

rr_StrategyPortfolioConcentration

The Fund will concentrate its investments in the real estate industry.

Risk [Heading]

rr_RiskHeading

Principal Risks:

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Industry Concentration Risk. The Fund’s strategy of concentrating its investments in issuers engaged in the real estate industry means that the Fund’s performance will be closely tied to the performance of that market segment.  The Fund will be more susceptible to adverse economic, market, political or regulatory occurrences affecting the real estate industry than a less concentrated fund.

Interest Rate Risk.  In general, when interest rates rise, the market values of real estate and real estate companies decline.  Interest rates across the U.S. economy have recently increased and may continue to increase, thereby heightening the Fund’s exposure to the risks associated with rising interest rates.

Liquidity Risk.  Certain investments may be difficult or impossible to sell at a favorable time or price.  Market developments may cause the Fund’s investments to become less liquid and subject to erratic price movements.  Liquidity risk is heightened for real estate companies and REITs with smaller market capitalizations, limited investments, larger amounts of debt, or higher levels of exposure to sub-prime mortgages.

Market Risk.  The prices of equity securities, including securities issued by REITs,  may decline or experience volatility over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with securities of mid- and small-size companies is generally greater than that associated with securities of larger, more established issuers because securities of mid- and small-size issuers tend to experience sharper price fluctuations.  At times, it may be difficult to sell securities of mid-to-small-size issuers at reasonable prices.

Non-Diversification Risk.  The Fund is non-diversified and, as such, its assets may be invested in a limited number of issuers. This means that the Fund’s performance may be substantially impacted by the change in value of even a single holding.

Prepayment and Extension Risk.  When interest rates decline, borrowers tend to refinance their mortgages.  When this occurs, mortgages may suffer a higher rate of prepayment and a mortgage or hybrid REIT’s income and share price may decline.  Conversely, when interest rates rise, borrowers tend to repay their mortgages less quickly, which generally increases a mortgage or hybrid REIT’s sensitivity to interest rates and its potential for price declines.

Real Estate Investments Risk.  The Fund is subject to the risks related to investments in real estate,  including declines in the real estate market, decreases in property revenues, increases in interest rates, increases in property taxes and operating expenses, legal and regulatory changes, a lack of credit or capital, defaults by borrowers or tenants, environmental problems and natural disasters.

REIT Risk.  In addition to the risks associated with the real estate industry, REITs are subject to additional risks, including those related to adverse governmental actions, declines in property value, and the potential failure to qualify for federal tax-free “pass-through” of distributed net income and net realized gains and exemption from registration as an investment company. REITs are dependent upon specialized management skills and may invest in relatively few properties, a small geographic area or a small number of property types.  As a result, investments in REITs may be volatile.  REITs are pooled investment vehicles with their own fees and expenses and the Fund will indirectly bear a proportionate share of those fees and expenses.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Risk Lose Money [Text]

rr_RiskLoseMoney

You can lose money by investing in the Fund.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

The Fund is non-diversified and, as such, its assets may be invested in a limited number of issuers. This means that the Fund’s performance may be substantially impacted by the change in value of even a single holding.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance:

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for the 1-year and Life of Fund periods compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the Fund.

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total Annual Returns For Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown, the highest quarterly return was 6.67% (for the quarter ended March 31, 2016) and the lowest quarterly return was -2.64% (for the quarter ended September 30, 2017).

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

The highest quarterly return was 6.67% (for the quarter ended March 31, 2016)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2016

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

6.67%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

The lowest quarterly return was -2.64% (for the quarter ended September 30, 2017)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2017

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(2.64%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns For Periods Ended December 31, 2017

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

First Investors Life Series Real Estate Fund | Dow Jones U.S. Select REIT Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

3.76%

Life of Fund

rr_AverageAnnualReturnSinceInception

6.13%

First Investors Life Series Real Estate Fund | First Investors Life Series Real Estate Fund

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.75%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.36%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

1.11%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 113

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

353

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

612

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,352

Annual Return 2016

rr_AnnualReturn2016

6.57%

Annual Return 2017

rr_AnnualReturn2017

1.27%

1 Year

rr_AverageAnnualReturnYear01

1.27%

Life of Fund

rr_AverageAnnualReturnSinceInception

3.47%

Inception Date

rr_AverageAnnualReturnInceptionDate

May 01, 2015

XML

First Investors Life Series Select Growth Fund

First Investors Life Series Select Growth Fund

Investment Objective:

The Fund seeks long-term growth of capital.

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 Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher. 

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	First Investors Life Series Select Growth Fund First Investors Life Series Select Growth Fund
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	First Investors Life Series Select Growth Fund First Investors Life Series Select Growth Fund
Management Fees	0.75%
Distribution and Service (12b-1) Fees	none
Other Expenses	0.06%
Total Annual Fund Operating Expenses	0.81%

Example

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Expense Example	1 year	3 years	5 years	10 years
First Investors Life Series Select Growth Fund | First Investors Life Series Select Growth Fund | USD ($)	83	259	450	1,002

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 52% of the average value of its portfolio.

Principal Investment Strategies:

The Fund invests in a portfolio of approximately 40-45 common stocks that the Fund’s subadviser, Smith Asset Management Group, L.P. (“Smith”), believes offers the best potential for earnings growth with the lowest risk of negative earnings surprises.

Smith employs quantitative and qualitative analysis to identify high quality companies that it believes have the ability to accelerate earnings growth and exceed investor expectations.  Beginning with a universe of stocks that includes large-, mid- and small-size companies, Smith’s investment team uses risk control and valuation screens primarily based on valuation, financial quality, stock volatility and corporate governance, to eliminate stocks that are highly volatile or are more likely to underperform the market.

Stocks that pass the initial screens are then evaluated using a proprietary methodology and fundamental analysis to produce a list of 80-100 eligible companies with a high probability of earnings growth that exceeds investor expectations.  The analysis includes an evaluation of changes in Wall Street opinions, individual analysts’ historical accuracy, earnings quality analysis and corporate governance practices.  Smith then constructs the Fund’s portfolio based on a traditional fundamental analysis of the companies identified on the list to understand their business prospects, earnings potential, strength of management and competitive positioning. 

Stocks may be sold if they exhibit negative investment or performance characteristics, including: a negative earnings forecast or report, valuation concerns, company officials’ downward guidance on company performance or earnings or announcement of a buyout.  Additionally, from time to time, in pursuing its investment strategies, the Fund may hold significant investments (25% or more of its assets) in a specific market sector, including the information technology sector.

Principal Risks:

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Focused Portfolio Risk.  Because the Fund generally invests in a limited portfolio of only 40 to 45 stocks, its performance may be more volatile than other funds whose portfolios may contain a larger number of securities.

Growth Stock Risk.  The Fund’s focus on growth stocks increases the potential volatility of its share price.  If expectations are not met, the prices of these stocks may decline significantly.

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with stocks of mid- and small-size companies is generally greater than that associated with stocks of larger, more established companies because stocks of mid- and small-size companies tend to experience sharper price fluctuations.  At times, it may be difficult to sell mid- to small-size company stocks at reasonable prices.

Sector Risk.  The Fund may hold a significant amount of investments in similar businesses, which could be affected by the same economic or market conditions.  To the extent the Fund invests significantly in the information technology sector, the value of the Fund's shares may be particularly vulnerable to factors affecting that sector, such as intense competition and potentially rapid product obsolescence. Companies in this sector also are heavily dependent on intellectual property rights and may be adversely affected by the loss or impairment of those rights.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Performance:

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.

Total Annual Returns For Calendar Years Ended December 31

During the periods shown, the highest quarterly return was 15.08% (for the quarter ended March 31, 2012) and the lowest quarterly return was -24.25% (for the quarter ended December 31, 2008).

Average Annual Total Returns For Periods Ended December 31, 2017

Average Annual Returns - First Investors Life Series Select Growth Fund	1 Year	5 Years	10 Years
First Investors Life Series Select Growth Fund	32.80%	16.60%	7.19%
Russell 3000 Growth Index (reflects no deduction for fees, expenses or taxes)	29.59%	17.16%	9.93%

XML

Label

Element

Value

First Investors Life Series Select Growth Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

First Investors Life Series Select Growth Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective:

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term growth of capital.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund:

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher. 

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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 [Text Block]

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 52% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

52.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund invests in a portfolio of approximately 40-45 common stocks that the Fund’s subadviser, Smith Asset Management Group, L.P. (“Smith”), believes offers the best potential for earnings growth with the lowest risk of negative earnings surprises.

Smith employs quantitative and qualitative analysis to identify high quality companies that it believes have the ability to accelerate earnings growth and exceed investor expectations.  Beginning with a universe of stocks that includes large-, mid- and small-size companies, Smith’s investment team uses risk control and valuation screens primarily based on valuation, financial quality, stock volatility and corporate governance, to eliminate stocks that are highly volatile or are more likely to underperform the market.

Stocks that pass the initial screens are then evaluated using a proprietary methodology and fundamental analysis to produce a list of 80-100 eligible companies with a high probability of earnings growth that exceeds investor expectations.  The analysis includes an evaluation of changes in Wall Street opinions, individual analysts’ historical accuracy, earnings quality analysis and corporate governance practices.  Smith then constructs the Fund’s portfolio based on a traditional fundamental analysis of the companies identified on the list to understand their business prospects, earnings potential, strength of management and competitive positioning. 

Stocks may be sold if they exhibit negative investment or performance characteristics, including: a negative earnings forecast or report, valuation concerns, company officials’ downward guidance on company performance or earnings or announcement of a buyout.  Additionally, from time to time, in pursuing its investment strategies, the Fund may hold significant investments (25% or more of its assets) in a specific market sector, including the information technology sector.

Risk [Heading]

rr_RiskHeading

Principal Risks:

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Focused Portfolio Risk.  Because the Fund generally invests in a limited portfolio of only 40 to 45 stocks, its performance may be more volatile than other funds whose portfolios may contain a larger number of securities.

Growth Stock Risk.  The Fund’s focus on growth stocks increases the potential volatility of its share price.  If expectations are not met, the prices of these stocks may decline significantly.

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with stocks of mid- and small-size companies is generally greater than that associated with stocks of larger, more established companies because stocks of mid- and small-size companies tend to experience sharper price fluctuations.  At times, it may be difficult to sell mid- to small-size company stocks at reasonable prices.

Sector Risk.  The Fund may hold a significant amount of investments in similar businesses, which could be affected by the same economic or market conditions.  To the extent the Fund invests significantly in the information technology sector, the value of the Fund's shares may be particularly vulnerable to factors affecting that sector, such as intense competition and potentially rapid product obsolescence. Companies in this sector also are heavily dependent on intellectual property rights and may be adversely affected by the loss or impairment of those rights.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Risk Lose Money [Text]

rr_RiskLoseMoney

You can lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance:

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the Fund.

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total Annual Returns For Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown, the highest quarterly return was 15.08% (for the quarter ended March 31, 2012) and the lowest quarterly return was -24.25% (for the quarter ended December 31, 2008).

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

The highest quarterly return was 15.08% (for the quarter ended March 31, 2012)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2012

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

15.08%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

The lowest quarterly return was -24.25% (for the quarter ended December 31, 2008)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(24.25%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns For Periods Ended December 31, 2017

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

First Investors Life Series Select Growth Fund | Russell 3000 Growth Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

29.59%

5 Years

rr_AverageAnnualReturnYear05

17.16%

10 Years

rr_AverageAnnualReturnYear10

9.93%

First Investors Life Series Select Growth Fund | First Investors Life Series Select Growth Fund

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.75%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.06%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.81%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 83

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

259

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

450

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,002

Annual Return 2008

rr_AnnualReturn2008

(41.47%)

Annual Return 2009

rr_AnnualReturn2009

9.90%

Annual Return 2010

rr_AnnualReturn2010

21.10%

Annual Return 2011

rr_AnnualReturn2011

5.25%

Annual Return 2012

rr_AnnualReturn2012

13.30%

Annual Return 2013

rr_AnnualReturn2013

33.15%

Annual Return 2014

rr_AnnualReturn2014

13.53%

Annual Return 2015

rr_AnnualReturn2015

3.21%

Annual Return 2016

rr_AnnualReturn2016

4.04%

Annual Return 2017

rr_AnnualReturn2017

32.80%

1 Year

rr_AverageAnnualReturnYear01

32.80%

5 Years

rr_AverageAnnualReturnYear05

16.60%

10 Years

rr_AverageAnnualReturnYear10

7.19%

XML

First Investors Life Series Special Situations Fund

First Investors Life Series Special Situations Fund

Investment Objective:

The Fund seeks long-term growth of capital.

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 Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher. 

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	First Investors Life Series Special Situations Fund First Investors Life Series Special Situations Fund
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	First Investors Life Series Special Situations Fund First Investors Life Series Special Situations Fund
Management Fees	0.75%
Distribution and Service (12b-1) Fees	none
Other Expenses	0.06%
Total Annual Fund Operating Expenses	0.81%

Example

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether do you do or do not redeem your shares, your costs would be:

Expense Example	1 year	3 years	5 years	10 years
First Investors Life Series Special Situations Fund | First Investors Life Series Special Situations Fund | USD ($)	83	259	450	1,002

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 38% of the average value of its portfolio.

Principal Investment Strategies:

The Fund invests primarily in common stocks of small-size companies that the Fund’s adviser believes are undervalued, and generally invests in companies that are experiencing a “special situation” that makes them undervalued relative to their long-term potential.  Developments creating special situations may include mergers, spin-offs, litigation resolution, new products, or management changes.  The Fund may invest in stocks of mid-size or large companies.  The Fund also may invest in exchange-traded funds (“ETFs”) to gain exposure to stocks and in real estate investment trusts (“REITs”).

The Fund uses a “bottom-up” approach to selecting investments.  The Fund uses fundamental research to search for companies that have one or more of the following: a strong balance sheet; experienced management; above-average earnings growth potential; and stocks that are attractively priced. 

The Fund may sell a stock if it becomes fully valued, it appreciates in value to the point that it is no longer a small-size company stock, its fundamentals have deteriorated or alternative investments become more attractive.

Principal Risks:

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Exchange-Traded Funds Risk.  The risks of investing in an ETF typically reflect the risks of the instruments in which the ETF invests.  In addition, because ETFs are investment companies, the Fund will bear its proportionate share of the fees and expenses of an investment in an ETF. As a result, the Fund’s expenses may be higher and performance may be lower.

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

REIT Risk.  In addition to the risks associated with the real estate industry, which include declines in the real estate market, decreases in property revenues and increases in property taxes and operating expenses, REITs are subject to additional risks, including those related to adverse governmental actions, declines in property value, and the potential failure to qualify for federal tax-free “pass-through” of distributed net income and net realized gains and exemption from registration as an investment company. REITs are dependent upon specialized management skills and may invest in relatively few properties, a small geographic area or a small number of property types.  As a result, investments in REITs may be volatile.  REITs are pooled investment vehicles with their own fees and expenses, and the Fund will indirectly bear a proportionate share of those fees and expenses.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

Small-Size and Mid-Size Company Risk.  The market risk associated with stocks of small- and mid-size companies is generally greater than that associated with stocks of larger, more established companies because stocks of small- and mid-size companies tend to experience sharper price fluctuations.  At times, it may be difficult to sell small- to-mid size company stocks at reasonable prices.

Undervalued Securities Risk.  The Fund seeks to invest in stocks that are undervalued and that will rise in value due to anticipated events or changes in investor perceptions.  If these developments do not occur, the market price of these securities may not rise as expected or may fall.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Performance:

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.  In addition, prior to September 23, 2013, the Fund was managed by a subadviser. 

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.

Total Annual Returns For Calendar Years Ended December 31

During the periods shown, the highest quarterly return was 17.19% (for the quarter ended June 30, 2009) and the lowest quarterly return was -24.00% (for the quarter ended December 31, 2008).

Average Annual Total Returns For Periods Ended December 31, 2017

Average Annual Returns - First Investors Life Series Special Situations Fund		1 Year	5 Years	10 Years
First Investors Life Series Special Situations Fund		18.26%	13.70%	8.97%
Russell 2000 Value Index (reflects no deduction for fees, expenses or taxes)	[1]	7.84%	13.01%	8.17%
Russell 2000 Index (reflects no deduction for fees, expenses or taxes)		14.65%	14.12%	8.71%

[1] The Fund changed its primary broad-based securities index to the Russell 2000 Value Index from the Russell 2000 Index as of March 14, 2018. The Fund elected to use the new index because it more closely reflects the Fund's investment strategies.

XML

Label

Element

Value

First Investors Life Series Special Situations Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

First Investors Life Series Special Situations Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective:

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term growth of capital.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund:

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher. 

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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 [Text Block]

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 38% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

38.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether do you do or do not redeem your shares, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund invests primarily in common stocks of small-size companies that the Fund’s adviser believes are undervalued, and generally invests in companies that are experiencing a “special situation” that makes them undervalued relative to their long-term potential.  Developments creating special situations may include mergers, spin-offs, litigation resolution, new products, or management changes.  The Fund may invest in stocks of mid-size or large companies.  The Fund also may invest in exchange-traded funds (“ETFs”) to gain exposure to stocks and in real estate investment trusts (“REITs”).

The Fund uses a “bottom-up” approach to selecting investments.  The Fund uses fundamental research to search for companies that have one or more of the following: a strong balance sheet; experienced management; above-average earnings growth potential; and stocks that are attractively priced. 

The Fund may sell a stock if it becomes fully valued, it appreciates in value to the point that it is no longer a small-size company stock, its fundamentals have deteriorated or alternative investments become more attractive.

Risk [Heading]

rr_RiskHeading

Principal Risks:

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Exchange-Traded Funds Risk.  The risks of investing in an ETF typically reflect the risks of the instruments in which the ETF invests.  In addition, because ETFs are investment companies, the Fund will bear its proportionate share of the fees and expenses of an investment in an ETF. As a result, the Fund’s expenses may be higher and performance may be lower.

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.

REIT Risk.  In addition to the risks associated with the real estate industry, which include declines in the real estate market, decreases in property revenues and increases in property taxes and operating expenses, REITs are subject to additional risks, including those related to adverse governmental actions, declines in property value, and the potential failure to qualify for federal tax-free “pass-through” of distributed net income and net realized gains and exemption from registration as an investment company. REITs are dependent upon specialized management skills and may invest in relatively few properties, a small geographic area or a small number of property types.  As a result, investments in REITs may be volatile.  REITs are pooled investment vehicles with their own fees and expenses, and the Fund will indirectly bear a proportionate share of those fees and expenses.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

Small-Size and Mid-Size Company Risk.  The market risk associated with stocks of small- and mid-size companies is generally greater than that associated with stocks of larger, more established companies because stocks of small- and mid-size companies tend to experience sharper price fluctuations.  At times, it may be difficult to sell small- to-mid size company stocks at reasonable prices.

Undervalued Securities Risk.  The Fund seeks to invest in stocks that are undervalued and that will rise in value due to anticipated events or changes in investor perceptions.  If these developments do not occur, the market price of these securities may not rise as expected or may fall.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Risk Lose Money [Text]

rr_RiskLoseMoney

You can lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance:

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for 1, 5, and 10 years compare to those of a broad measure of market performance.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.  In addition, prior to September 23, 2013, the Fund was managed by a subadviser. 

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the Fund.

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total Annual Returns For Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown, the highest quarterly return was 17.19% (for the quarter ended June 30, 2009) and the lowest quarterly return was -24.00% (for the quarter ended December 31, 2008).

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

The highest quarterly return was 17.19% (for the quarter ended June 30, 2009)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

17.19%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

The lowest quarterly return was -24.00% (for the quarter ended December 31, 2008)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(24.00%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns For Periods Ended December 31, 2017

Performance Table Market Index Changed

rr_PerformanceTableMarketIndexChanged

The Fund changed its primary broad-based securities index to the Russell 2000 Value Index from the Russell 2000 Index as of March 14, 2018. The Fund elected to use the new index because it more closely reflects the Fund’s investment strategies.

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

First Investors Life Series Special Situations Fund | Russell 2000 Value Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

7.84%

^[1]

5 Years

rr_AverageAnnualReturnYear05

13.01%

^[1]

10 Years

rr_AverageAnnualReturnYear10

8.17%

^[1]

First Investors Life Series Special Situations Fund | Russell 2000 Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

14.65%

5 Years

rr_AverageAnnualReturnYear05

14.12%

10 Years

rr_AverageAnnualReturnYear10

8.71%

First Investors Life Series Special Situations Fund | First Investors Life Series Special Situations Fund

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.75%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.06%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.81%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 83

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

259

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

450

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,002

Annual Return 2008

rr_AnnualReturn2008

(33.25%)

Annual Return 2009

rr_AnnualReturn2009

30.77%

Annual Return 2010

rr_AnnualReturn2010

26.57%

Annual Return 2011

rr_AnnualReturn2011

2.24%

Annual Return 2012

rr_AnnualReturn2012

10.01%

Annual Return 2013

rr_AnnualReturn2013

30.88%

Annual Return 2014

rr_AnnualReturn2014

6.30%

Annual Return 2015

rr_AnnualReturn2015

(0.52%)

Annual Return 2016

rr_AnnualReturn2016

16.10%

Annual Return 2017

rr_AnnualReturn2017

18.26%

1 Year

rr_AverageAnnualReturnYear01

18.26%

5 Years

rr_AverageAnnualReturnYear05

13.70%

10 Years

rr_AverageAnnualReturnYear10

8.97%

[1] The Fund changed its primary broad-based securities index to the Russell 2000 Value Index from the Russell 2000 Index as of March 14, 2018. The Fund elected to use the new index because it more closely reflects the Fund's investment strategies.

XML

First Investors Life Series Total Return Fund

First Investors Life Series Total Return Fund

Investment Objective:

The Fund seeks high, long-term total investment return consistent with moderate investment risk.

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 Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher. 

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees	First Investors Life Series Total Return Fund First Investors Life Series Total Return Fund
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none
Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses	First Investors Life Series Total Return Fund First Investors Life Series Total Return Fund
Management Fees	0.75%
Distribution and Service (12b-1) Fees	none
Other Expenses	0.11%
Total Annual Fund Operating Expenses	0.86%

Example

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Expense Example	1 year	3 years	5 years	10 years
First Investors Life Series Total Return Fund | First Investors Life Series Total Return Fund | USD ($)	88	274	477	1,061

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 48% of the average value of its portfolio.

Principal Investment Strategies:

The Fund allocates its assets among stocks, bonds and money market instruments.  While the percentage of assets allocated to each asset class is flexible rather than fixed, the Fund normally invests at least 50% of its net assets in stocks and at least 30% in bonds, cash and money market instruments.  The percentages may change due to, among other things, market fluctuations or reallocation decisions by the Fund’s portfolio managers.

In connection with the determination of the Fund’s allocation ranges, the Adviser considers various factors, including existing and projected market conditions for equity and fixed income securities.  Once the asset allocation for bonds, stocks and money market instruments has been set, the Adviser uses fundamental research and analysis to determine which particular investments to purchase or sell.  The percentage allocations within the above ranges may change due to, among other things, market fluctuations or reallocation decisions by Foresters Investment Management Company, Inc. (“Adviser”). Reallocations are expected to occur infrequently and only when the Fund’s investments in bonds, stocks and money market instruments fall outside of the above ranges.

The Fund’s investments in stocks are normally diversified among common stocks of large-, mid- and small-size companies that offer the potential for capital growth, current income, or both.  In selecting stocks, the Adviser considers, among other things, the issuer’s financial strength, management, earnings growth potential and history (if any) of paying dividends.

The Fund’s investments in bonds are primarily diversified among different types of bonds and other debt securities, including corporate bonds, U.S. Government securities and mortgage-backed and other asset-backed securities.  The Adviser selects bonds by first considering the outlook for the economy and interest rates, and thereafter, a particular security’s characteristics.  The Adviser may sell a security if it becomes fully valued, its fundamentals have deteriorated, alternative investments become more attractive or if it is necessary to rebalance the portfolio.

To a lesser extent, the Fund also invests in high yield, below investment grade corporate bonds (commonly known as “high yield” or “junk bonds”).  The Adviser has retained Muzinich & Co, Inc. (“Muzinich”) as a subadviser to manage this portion of the Fund. High yield bonds include bonds that are rated below Baa3 by Moody’s Investors Service, Inc. or below BBB- by S&P Global Ratings as well as unrated bonds that are determined by Muzinich to be of equivalent quality.  Muzinich will consider ratings assigned by ratings agencies in selecting high yield bonds, but relies principally on its own research and investment analysis.  In managing its portion of the Fund, Muzinich focuses on investments it believes can generate attractive and consistent income.  Muzinich may sell a bond when it shows deteriorating fundamentals or it falls short of the portfolio manager’s expectations.

In addition, the Adviser may also invest in exchange-traded funds (“ETFs”) that could expose the Fund to high yield securities.

The Fund may also invest in U.S. Treasury futures and options on U.S. Treasury futures to hedge against changes in interest rates.

Principal Risks:

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Allocation Risk.  The Fund may allocate assets to investment classes that underperform other classes.  For example, the Fund may be overweighted in stocks when the stock market is falling and the bond market is rising.

Credit Risk.  A debt issuer may become unable or unwilling to pay interest or principal when due.  The prices of debt securities are affected by the credit quality of the issuer and, in the case of mortgage-backed and other asset-backed securities, the credit quality of the underlying loans.  Securities issued by U.S. Government-sponsored enterprises are supported only by the credit of the issuing entity.

Derivatives Risk.  Investments in U.S. Treasury futures and options on U.S. Treasury futures to hedge against changes in interest rates involve risks, such as potential losses if interest rates do not move as expected and the potential for greater losses than if these techniques had not been used.  Investments in derivatives can increase the volatility of the Fund’s share price and may expose it to significant additional costs.  Derivatives may be difficult to sell, unwind, or value.

Exchange-Traded Funds Risk.  The risks of investing in an ETF typically reflect the risks of the types of instruments in which the ETF invests. In addition, because ETFs are investment companies, the Fund will bear its proportionate share of the fees and expenses of an investment in an ETF. As a result, the Fund’s expenses may be higher and performance may be lower.

High Yield Securities Risk.  High yield debt securities (commonly known as “junk bonds”) have greater credit risk than higher quality debt securities because their issuers may not be as financially strong.  High yield securities are inherently speculative due to the risk associated with the issuer’s ability to make principal and interest payments.  During times of economic stress, high yield securities issuers may be unable to access credit to refinance their bonds or meet their credit obligations.

Interest Rate Risk.  In general, when interest rates rise, the market value of a debt security declines, and when interest rates decline, the market value of a debt security increases.  Interest rates across the U.S. economy have recently increased and may continue to increase, thereby heightening the Fund’s exposure to the risks associated with rising interest rates.  Securities with longer maturities and durations are generally more sensitive to interest rate changes.

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  Similarly, bond prices fluctuate in value with changes in interest rates, the economy and circumstances directly involving issuers.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.  Certain investments may be difficult or impossible to sell at a favorable time or price when the Fund requires liquidity to make redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with stocks of mid- and small-size companies is generally greater than that associated with stocks of larger, more established companies because stocks of mid- and small-size companies tend to experience sharper price fluctuations.  At times, it may be difficult to sell mid- to small-size company stocks at reasonable prices.

Prepayment and Extension Risk.  When interest rates decline, borrowers tend to refinance their loans and the loans that back mortgage-backed and other asset-backed securities suffer a higher rate of prepayment.  This could cause a decrease in the Fund’s income and share price.  Conversely, when interest rates rise, borrowers tend to repay their loans less quickly, which will generally increase both the Fund’s sensitivity to rising interest rates and its potential for price declines.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Performance:

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for the 1-year, 5-year and Life of Fund periods compare to those of an index that is a broad measure of market performance for equity securities and an index that is a broad measure of market performance for fixed-income securities.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.  Prior to May 1, 2018, Muzinich did not serve as a subadviser to the Fund.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown. 

Total Annual Returns For Calendar Years Ended December 31

During the periods shown, the highest quarterly return was 6.04% (for the quarter ended March 31, 2013) and the lowest quarterly return was -5.43% (for the quarter ended September 30, 2015).

Average Annual Total Returns For Periods Ended December 31, 2017

Average Annual Returns - First Investors Life Series Total Return Fund	1 Year	5 Years	Life of Fund
First Investors Life Series Total Return Fund (Inception Date: 12/17/12)	11.75%	7.77%	7.55%
S&P 500 Index (reflects no deduction for fees, expenses or taxes)	21.83%	15.79%	15.60%
BofA Merrill Lynch U.S. Corporate, Government & Mortgage Index (reflects no deduction for fees, expenses or taxes)	3.63%	2.13%	2.16%

XML

Label

Element

Value

First Investors Life Series Total Return Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

First Investors Life Series Total Return Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective:

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks high, long-term total investment return consistent with moderate investment risk.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses of the Fund:

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.  Investments in the Fund can only be made through a variable annuity contract or life insurance policy offered by a participating insurance company.  This table does not reflect the fees and expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  For information regarding those fees and expenses, please refer to the applicable variable annuity contract or life insurance policy prospectus.  If those fees and expenses were included, the overall fees and expenses shown in the table would be higher. 

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

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 [Text Block]

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 may indicate higher transaction costs.  These costs, which are not reflected in annual fund operating expenses or in the Example, affect the Fund’s performance.  During the most recent fiscal year, the Fund’s portfolio turnover rate was 48% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

48.00%

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

The Example is intended to help you compare the cost of investing in the 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.  The table below does not include the fees or expenses that are or may be imposed by a variable annuity contract or life insurance policy for which the Fund is an investment option.  If they were included, the expenses shown in the table below would be higher.  Although your actual costs may be higher or lower, based on these assumptions, whether you do or do not redeem your shares, your costs would be:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies:

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund allocates its assets among stocks, bonds and money market instruments.  While the percentage of assets allocated to each asset class is flexible rather than fixed, the Fund normally invests at least 50% of its net assets in stocks and at least 30% in bonds, cash and money market instruments.  The percentages may change due to, among other things, market fluctuations or reallocation decisions by the Fund’s portfolio managers.

In connection with the determination of the Fund’s allocation ranges, the Adviser considers various factors, including existing and projected market conditions for equity and fixed income securities.  Once the asset allocation for bonds, stocks and money market instruments has been set, the Adviser uses fundamental research and analysis to determine which particular investments to purchase or sell.  The percentage allocations within the above ranges may change due to, among other things, market fluctuations or reallocation decisions by Foresters Investment Management Company, Inc. (“Adviser”). Reallocations are expected to occur infrequently and only when the Fund’s investments in bonds, stocks and money market instruments fall outside of the above ranges.

The Fund’s investments in stocks are normally diversified among common stocks of large-, mid- and small-size companies that offer the potential for capital growth, current income, or both.  In selecting stocks, the Adviser considers, among other things, the issuer’s financial strength, management, earnings growth potential and history (if any) of paying dividends.

The Fund’s investments in bonds are primarily diversified among different types of bonds and other debt securities, including corporate bonds, U.S. Government securities and mortgage-backed and other asset-backed securities.  The Adviser selects bonds by first considering the outlook for the economy and interest rates, and thereafter, a particular security’s characteristics.  The Adviser may sell a security if it becomes fully valued, its fundamentals have deteriorated, alternative investments become more attractive or if it is necessary to rebalance the portfolio.

To a lesser extent, the Fund also invests in high yield, below investment grade corporate bonds (commonly known as “high yield” or “junk bonds”).  The Adviser has retained Muzinich & Co, Inc. (“Muzinich”) as a subadviser to manage this portion of the Fund. High yield bonds include bonds that are rated below Baa3 by Moody’s Investors Service, Inc. or below BBB- by S&P Global Ratings as well as unrated bonds that are determined by Muzinich to be of equivalent quality.  Muzinich will consider ratings assigned by ratings agencies in selecting high yield bonds, but relies principally on its own research and investment analysis.  In managing its portion of the Fund, Muzinich focuses on investments it believes can generate attractive and consistent income.  Muzinich may sell a bond when it shows deteriorating fundamentals or it falls short of the portfolio manager’s expectations.

In addition, the Adviser may also invest in exchange-traded funds (“ETFs”) that could expose the Fund to high yield securities.

The Fund may also invest in U.S. Treasury futures and options on U.S. Treasury futures to hedge against changes in interest rates.

Risk [Heading]

rr_RiskHeading

Principal Risks:

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

You can lose money by investing in the Fund.  There is no guarantee that the Fund will meet its investment objective.  Here are the principal risks of investing in the Fund:

Allocation Risk.  The Fund may allocate assets to investment classes that underperform other classes.  For example, the Fund may be overweighted in stocks when the stock market is falling and the bond market is rising.

Credit Risk.  A debt issuer may become unable or unwilling to pay interest or principal when due.  The prices of debt securities are affected by the credit quality of the issuer and, in the case of mortgage-backed and other asset-backed securities, the credit quality of the underlying loans.  Securities issued by U.S. Government-sponsored enterprises are supported only by the credit of the issuing entity.

Derivatives Risk.  Investments in U.S. Treasury futures and options on U.S. Treasury futures to hedge against changes in interest rates involve risks, such as potential losses if interest rates do not move as expected and the potential for greater losses than if these techniques had not been used.  Investments in derivatives can increase the volatility of the Fund’s share price and may expose it to significant additional costs.  Derivatives may be difficult to sell, unwind, or value.

Exchange-Traded Funds Risk.  The risks of investing in an ETF typically reflect the risks of the types of instruments in which the ETF invests. In addition, because ETFs are investment companies, the Fund will bear its proportionate share of the fees and expenses of an investment in an ETF. As a result, the Fund’s expenses may be higher and performance may be lower.

High Yield Securities Risk.  High yield debt securities (commonly known as “junk bonds”) have greater credit risk than higher quality debt securities because their issuers may not be as financially strong.  High yield securities are inherently speculative due to the risk associated with the issuer’s ability to make principal and interest payments.  During times of economic stress, high yield securities issuers may be unable to access credit to refinance their bonds or meet their credit obligations.

Interest Rate Risk.  In general, when interest rates rise, the market value of a debt security declines, and when interest rates decline, the market value of a debt security increases.  Interest rates across the U.S. economy have recently increased and may continue to increase, thereby heightening the Fund’s exposure to the risks associated with rising interest rates.  Securities with longer maturities and durations are generally more sensitive to interest rate changes.

Market Risk.  Stock prices may decline over short or even extended periods due to general economic and market conditions, adverse political or regulatory developments or interest rate fluctuations.  Similarly, bond prices fluctuate in value with changes in interest rates, the economy and circumstances directly involving issuers.  Adverse market events may lead to increased redemptions, which could cause the Fund to experience a loss or difficulty in selling securities to meet redemptions.  Certain investments may be difficult or impossible to sell at a favorable time or price when the Fund requires liquidity to make redemptions.

Mid-Size and Small-Size Company Risk.  The market risk associated with stocks of mid- and small-size companies is generally greater than that associated with stocks of larger, more established companies because stocks of mid- and small-size companies tend to experience sharper price fluctuations.  At times, it may be difficult to sell mid- to small-size company stocks at reasonable prices.

Prepayment and Extension Risk.  When interest rates decline, borrowers tend to refinance their loans and the loans that back mortgage-backed and other asset-backed securities suffer a higher rate of prepayment.  This could cause a decrease in the Fund’s income and share price.  Conversely, when interest rates rise, borrowers tend to repay their loans less quickly, which will generally increase both the Fund’s sensitivity to rising interest rates and its potential for price declines.

Security Selection Risk.  Securities selected by the portfolio manager may perform differently than the overall market or may not meet expectations.

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. 

Risk Lose Money [Text]

rr_RiskLoseMoney

You can lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

An investment in the Fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance:

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund.  The bar chart shows changes in the Fund’s performance from year to year.  The table shows how the Fund’s average annual returns for the 1-year, 5-year and Life of Fund periods compare to those of an index that is a broad measure of market performance for equity securities and an index that is a broad measure of market performance for fixed-income securities.  The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.  Prior to May 1, 2018, Muzinich did not serve as a subadviser to the Fund.

The bar chart and table do not reflect fees and expenses that may be deducted by the variable annuity contract or variable life insurance policy through which you invest.  If they were included, the returns would be less than those shown. 

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the Fund.

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The Fund’s past performance is not necessarily an indication of how the Fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Total Annual Returns For Calendar Years Ended December 31

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown, the highest quarterly return was 6.04% (for the quarter ended March 31, 2013) and the lowest quarterly return was -5.43% (for the quarter ended September 30, 2015).

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

The highest quarterly return was 6.04% (for the quarter ended March 31, 2013)

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2013

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

6.04%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

The lowest quarterly return was -5.43% (for the quarter ended September 30, 2015)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(5.43%)

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns For Periods Ended December 31, 2017

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

(reflects no deduction for fees, expenses or taxes)

First Investors Life Series Total Return Fund | S&P 500 Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

21.83%

5 Years

rr_AverageAnnualReturnYear05

15.79%

Life of Fund

rr_AverageAnnualReturnSinceInception

15.60%

First Investors Life Series Total Return Fund | BofA Merrill Lynch U.S. Corporate, Government & Mortgage Index (reflects no deduction for fees, expenses or taxes)

Risk/Return:

rr_RiskReturnAbstract

1 Year

rr_AverageAnnualReturnYear01

3.63%

5 Years

rr_AverageAnnualReturnYear05

2.13%

Life of Fund

rr_AverageAnnualReturnSinceInception

2.16%

First Investors Life Series Total Return Fund | First Investors Life Series Total Return Fund

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of the lower of purchase price or redemption price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management Fees

rr_ManagementFeesOverAssets

0.75%

Distribution and Service (12b-1) Fees

rr_DistributionAndService12b1FeesOverAssets

none

Other Expenses

rr_OtherExpensesOverAssets

0.11%

Total Annual Fund Operating Expenses

rr_ExpensesOverAssets

0.86%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 88

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

274

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

477

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,061

Annual Return 2013

rr_AnnualReturn2013

17.02%

Annual Return 2014

rr_AnnualReturn2014

5.97%

Annual Return 2015

rr_AnnualReturn2015

(1.61%)

Annual Return 2016

rr_AnnualReturn2016

6.62%

Annual Return 2017

rr_AnnualReturn2017

11.75%

1 Year

rr_AverageAnnualReturnYear01

11.75%

5 Years

rr_AverageAnnualReturnYear05

7.77%

Life of Fund

rr_AverageAnnualReturnSinceInception

7.55%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 17, 2012

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Prospectus Date	rr_ProspectusDate	May 01, 2018