485BPOS

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM N-1A
REGISTRATION STATEMENT (No. 002-41839)
		UNDER THE SECURITIES ACT OF 1933	[X]
		Pre-Effective Amendment No. ____	[ ]
		Post-Effective Amendment No. 208	[X]
and
REGISTRATION STATEMENT (No. 811-02105)
		UNDER THE INVESTMENT COMPANY ACT OF 1940	[X]
		Amendment No. 208	[X]
Fidelity Salem Street Trust
(Exact Name of Registrant as Specified in Charter)
82 Devonshire St., Boston, Massachusetts 02109
(Address Of Principal Executive Offices) (Zip Code)
Registrant's Telephone Number: 617-563-7000
Scott C. Goebel, Secretary
82 Devonshire Street
Boston, Massachusetts 02109
(Name and Address of Agent for Service)
It is proposed that this filing will become effective
	(x)	immediately upon filing pursuant to paragraph (b).
	( )	on ( ) pursuant to paragraph (b) at 5:30 p.m. Eastern Time.
	( )	60 days after filing pursuant to paragraph (a)(1) at 5:30 p.m. Eastern Time.
	( )	on ( ) pursuant to paragraph (a)(1) of Rule 485 at 5:30 p.m. Eastern Time.
	( )	75 days after filing pursuant to paragraph (a)(2) at 5:30 p.m. Eastern Time.
	( )	on ( ) pursuant to paragraph (a)(2) of Rule 485 at 5:30 p.m. Eastern Time.
If appropriate, check the following box:
	( )	this post-effective amendment designates a new effective date for a previously filed post-effective amendment.

EXHIBIT INDEX

Exhibit	Exhibit No.
XBRL Instance Document	EX-101.INS
XBRL Taxonomy Extension Schema Document	EX-101.SCH
XBRL Taxonomy Extension Calculation Linkbase Document	EX-101.CAL
XBRL Taxonomy Extension Definition Linkbase Document	EX-101.DEF
XBRL Taxonomy Extension Labels Linkbase Document	EX-101.LAB
XBRL Taxonomy Extension Presentation Linkbase Document	EX-101.PRE

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant certifies that it meets all of the requirements for the effectiveness of this Registration Statement pursuant to Rule 485(b) under the Securities Act of 1933 and has duly caused this Post-Effective Amendment No. 208 to the Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Boston, and Commonwealth of Massachusetts, on the 15th day of November 2012.

	Fidelity Salem Street Trust
	By	/s/John R. Hebble
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||		John R. Hebble, President

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed below by the following persons in the capacities and on the dates indicated.

(Signature)		(Title)	(Date)
/s/John R. Hebble		President and Treasurer	November 15, 2012
John R. Hebble		(Principal Executive Officer)
/s/Christine Reynolds		Chief Financial Officer	November 15, 2012
Christine Reynolds		(Principal Financial Officer)
/s/Abigail P. Johnson		Trustee	November 15, 2012
Abigail P. Johnson
/s/James C. Curvey	*	Trustee	November 15, 2012
James C. Curvey
/s/Albert R. Gamper	*	Trustee	November 15, 2012
Albert R. Gamper
/s/Robert F. Gartland	*	Trustee	November 15, 2012
Robert F. Gartland
/s/Arthur E. Johnson	*	Trustee	November 15, 2012
Arthur E. Johnson
/s/Michael E. Kenneally	*	Trustee	November 15, 2012
Michael E. Kenneally
/s/James H. Keyes	*	Trustee	November 15, 2012
James H. Keyes
/s/Marie L. Knowles	*	Trustee	November 15, 2012
Marie L. Knowles
/s/Kenneth L. Wolfe	*	Trustee	November 15, 2012
Kenneth L. Wolfe

*	By:	/s/Joseph R. Fleming
		Joseph R. Fleming, pursuant to a power of attorney dated February 1, 2011 and filed herewith.

POWER OF ATTORNEY

We, the undersigned Directors or Trustees, as the case may be, of the following investment companies:

  Fidelity Aberdeen Street Trust Fidelity Advisor Series II Fidelity Advisor Series IV Fidelity Boylston Street Trust Fidelity California Municipal Trust Fidelity California Municipal Trust II Fidelity Central Investment Portfolios II LLC Fidelity Charles Street Trust Fidelity Colchester Street Trust Fidelity Court Street Trust Fidelity Court Street Trust II Fidelity Fixed-Income Trust Fidelity Garrison Street Trust Fidelity Hereford Street Trust Fidelity Income Fund   Fidelity Massachusetts Municipal Trust Fidelity Money Market Trust Fidelity Municipal Trust Fidelity Municipal Trust II Fidelity Newbury Street Trust Fidelity New York Municipal Trust Fidelity New York Municipal Trust II Fidelity Oxford Street Trust Fidelity Phillips Street Trust Fidelity Revere Street Trust Fidelity School Street Trust Fidelity Union Street Trust Fidelity Union Street Trust II Variable Insurance Products Fund V

in addition to any other investment company for which Fidelity Management & Research Company ("FMR") or an affiliate acts as investment adviser and for which the undersigned individuals serve as Directors or Trustees (collectively, the "Funds"), hereby revoke all previous powers of attorney we have given to sign and otherwise act in our names and behalf in matters involving any investment company for which FMR or an affiliate acts as investment adviser and hereby constitute and appoint Thomas C. Bogle, Joseph R. Fleming, John V. O'Hanlon, Robert W. Helm and Anthony H. Zacharski, each of them singly, our true and lawful attorneys-in-fact, with full power of substitution, and with full power to each of them, to sign for us and in our names in the appropriate capacities, all Registration Statements of the Funds on Form N-1A, or any successors thereto, any and all subsequent Amendments, Pre-Effective Amendments, or Post-Effective Amendments to said Registration Statements or any successors thereto, and any supplements or other instruments in connection therewith, and generally to do all such things in our names and behalf in connection therewith as said attorneys-in-fact deem necessary or appropriate, to comply with the provisions of the Securities Act of 1933 and the Investment Company Act of 1940, and all related requirements of the Securities and Exchange Commission. We hereby ratify and confirm all that said attorneys-in-fact or their substitutes may do or cause to be done by virtue hereof. This power of attorney is effective for all documents filed on or after February 1, 2011.

WITNESS our hands on this first day of February 1, 2011.

/s/James C. Curvey	/s/Michael E. Kenneally
James C. Curvey	Michael E. Kenneally
/s/Albert R. Gamper, Jr.	/s/James H. Keyes
Albert R. Gamper, Jr.	James H. Keyes
/s/Robert F. Gartland	/s/Marie L. Knowles
Robert F. Gartland	Marie L. Knowles
/s/Arthur E. Johnson	/s/Kenneth L. Wolfe
Arthur E. Johnson	Kenneth L. Wolfe

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	FIDELITY SALEM STREET TRUST
Prospectus Date	rr_ProspectusDate	Oct. 30, 2012
Document Creation Date	dei_DocumentCreationDate	Oct. 29, 2012

XML

A T B C | Fidelity Investment Grade Bond Fund

Fund Summary

Fund/Class:
Fidelity^® Investment Grade Bond Fund/Fidelity Advisor^® Investment Grade Bond Fund A, T, B, C

Investment Objective

The fund seeks a high level of current income.

Fee Table

The following table describes the fees and expenses that may be incurred when you buy, hold, or sell shares of the fund.

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or certain other Fidelity funds. More information about these and other discounts is available from your investment professional and in the Fund Distribution section beginning on page (Click Here) of the prospectus.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees A T B C Fidelity Investment Grade Bond Fund	Class A		Class T		Class B		Class C
Maximum sales charge (load) on purchases (as a % of offering price)	4.00%		4.00%		none		none
Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)	none	[1]	none	[1]	5.00%	[2]	1.00%	[3]

Annual class operating expenses
(expenses that you pay each year as a % of the value of your investment)

Annual Class Operating Expenses A T B C Fidelity Investment Grade Bond Fund	Class A	Class T	Class B	Class C
Management fee	0.32%	0.32%	0.32%	0.32%
Distribution and/or Service (12b-1) fees	0.25%	0.25%	0.90%	1.00%
Other expenses	0.21%	0.24%	0.28%	0.20%
Total annual operating expenses	0.78%	0.81%	1.50%	1.52%

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated and if you hold your shares:

Sell All Shares

Expense Example A T B C Fidelity Investment Grade Bond Fund (USD $)	Class A	Class T	Class B	Class C
1 year	476	479	653	255
3 years	639	648	774	480
5 years	816	832	1,018	829
10 years	1,327	1,362	1,504	1,813

Hold Shares

Expense Example, No Redemption A T B C Fidelity Investment Grade Bond Fund (USD $)	Class A	Class T	Class B	Class C
1 year	476	479	153	155
3 years	639	648	474	480
5 years	816	832	818	829
10 years	1,327	1,362	1,504	1,813

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 276% of the average value of its portfolio.

Principal Investment Strategies

• Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Aggregate Bond Index.
• Allocating assets across different market sectors and maturities.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Potentially investing in lower-quality debt securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Principal Investment Risks

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could lose money by investing in the fund.

Performance

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.advisor.fidelity.com for updated return information.

Year-by-Year Returns

The returns in the bar chart do not reflect any applicable sales charges; if sales charges were reflected, returns would be lower than those shown.

Calendar Years

During the periods shown in the chart for Class A:	Returns	Quarter ended
Highest Quarter Return	6.25%	September 30, 2009
Lowest Quarter Return	-3.49%	December 31, 2008
Year-to-Date Return	5.45%	September 30, 2012

Average Annual Returns

Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges. After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Average Annual Total Returns A T B C Fidelity Investment Grade Bond Fund	Past 1 year	Past 5 years	Life of class		Inception Date
Class A Return Before Taxes	3.40%	4.12%	4.33%	[1]	Aug. 27, 2002
Class A Return After Taxes on Distributions	2.35%	2.71%	2.79%	[1]	Aug. 27, 2002
Class A Return After Taxes on Distributions and Sale of Fund Shares	2.19%	2.66%	2.78%	[1]	Aug. 27, 2002
Class T Return Before Taxes	3.23%	4.06%	4.26%	[1]	Aug. 27, 2002
Class B Return Before Taxes	1.92%	3.87%	4.20%	[1]	Aug. 27, 2002
Class C Return Before Taxes	5.90%	4.17%	3.96%	[1]	Aug. 27, 2002
Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)	7.84%	6.50%	5.50%	[1]	Aug. 27, 2002

[1] Class A and Class T purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class T purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 0.75% or 0.25%, respectively.

[2] Declines over 6 years from 5.00% to 0%.

[3] On Class C shares redeemed less than one year after purchase.

[1] From August 27, 2002.

XML

F | Fidelity Series Investment Grade Bond Fund

Fund Summary

Fund/Class:
Fidelity^® Series Investment Grade Bond Fund/F

Investment Objective

The fund seeks a high level of current income.

Fee Table

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees (USD $)	F Fidelity Series Investment Grade Bond Fund Class F
Shareholder fees (fees paid directly from your investment)	none

Annual class operating expenses
(expenses that you pay each year as a % of the value of your investment)

Annual Class Operating Expenses	F Fidelity Series Investment Grade Bond Fund Class F
Management fee	0.35%
Distribution and/or Service (12b-1) fees	none
Other expenses	none
Total annual operating expenses	0.35%

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example (USD $)	F Fidelity Series Investment Grade Bond Fund Class F
1 year	36
3 years	113
5 years	197
10 years	443

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 158% of the average value of its portfolio.

Principal Investment Strategies

• Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Aggregate Bond Index.
• Allocating assets across different market sectors and maturities.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Potentially investing in lower-quality debt securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Principal Investment Risks

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could lose money by investing in the fund.

Performance

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.401k.com and log in for updated return information.

Year-by-Year Returns
Calendar Years

During the period shown in the chart:	Returns	Quarter ended
Highest Quarter Return	3.45%	September 30, 2011
Lowest Quarter Return	-0.94%	December 31, 2010
Year-to-Date Return	5.26%	September 30, 2012

Average Annual Returns

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Average Annual Total Returns F Fidelity Series Investment Grade Bond Fund	Past 1 year	Life of class		Inception Date
Class F Return Before Taxes	7.49%	8.81%	[1]	Jun. 26, 2009
Class F Return After Taxes on Distributions	6.23%	6.79%	[1]	Jun. 26, 2009
Class F Return After Taxes on Distributions and Sale of Fund Shares	5.34%	6.42%	[1]	Jun. 26, 2009
Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)	7.84%	7.32%	[1]	Jun. 26, 2009

[1] From June 26, 2009.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SALEM STREET TRUST

Prospectus Date

rr_ProspectusDate

Oct. 30, 2012

A T B C | Fidelity Investment Grade Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary

Fund/Class:
Fidelity^® Investment Grade Bond Fund/Fidelity Advisor^® Investment Grade Bond Fund A, T, B, C

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks a high level of current income.

Expense [Heading]

rr_ExpenseHeading

Fee Table

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy, hold, or sell shares of the fund.

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or certain other Fidelity funds. More information about these and other discounts is available from your investment professional and in the Fund Distribution section beginning on page (Click Here) of the prospectus.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees
(fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual class operating expenses
(expenses that you pay each year as a % 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 rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 276% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

276.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or certain other Fidelity funds.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

50,000

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated and if you hold your shares:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

Sell All Shares

Expense Example, No Redemption, By Year, Caption [Text]

rr_ExpenseExampleNoRedemptionByYearCaption

Hold Shares

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Aggregate Bond Index.
• Allocating assets across different market sectors and maturities.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Potentially investing in lower-quality debt securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could 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 deposit of a bank 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 information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.advisor.fidelity.com for updated return information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.advisor.fidelity.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) is not an indication of future performance.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Returns

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

The returns in the bar chart do not reflect any applicable sales charges; if sales charges were reflected, returns would be lower than those shown.

Calendar Years

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart for Class A:	Returns	Quarter ended
Highest Quarter Return	6.25%	September 30, 2009
Lowest Quarter Return	-3.49%	December 31, 2008
Year-to-Date Return	5.45%	September 30, 2012

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Returns

Performance Table Does Reflect Sales Loads

rr_PerformanceTableDoesReflectSalesLoads

Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges. After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

A T B C | Fidelity Investment Grade Bond Fund | Class A

Risk/Return:

rr_RiskReturnAbstract

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

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

4.00%

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

^[1]

Management fee

rr_ManagementFeesOverAssets

0.32%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.21%

Total annual operating expenses

rr_ExpensesOverAssets

0.78%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Class A and Class T purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class T purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 0.75% or 0.25%, respectively.

1 year

rr_ExpenseExampleYear01

476

3 years

rr_ExpenseExampleYear03

639

5 years

rr_ExpenseExampleYear05

816

10 years

rr_ExpenseExampleYear10

1,327

1 year

rr_ExpenseExampleNoRedemptionYear01

476

3 years

rr_ExpenseExampleNoRedemptionYear03

639

5 years

rr_ExpenseExampleNoRedemptionYear05

816

10 years

rr_ExpenseExampleNoRedemptionYear10

1,327

2003

rr_AnnualReturn2003

4.48%

2004

rr_AnnualReturn2004

4.30%

2005

rr_AnnualReturn2005

2.49%

2006

rr_AnnualReturn2006

4.42%

2007

rr_AnnualReturn2007

2.40%

2008

rr_AnnualReturn2008

(7.44%)

2009

rr_AnnualReturn2009

15.49%

2010

rr_AnnualReturn2010

8.10%

2011

rr_AnnualReturn2011

7.71%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2012

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

5.45%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

6.25%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(3.49%)

A T B C | Fidelity Investment Grade Bond Fund | Class T

Risk/Return:

rr_RiskReturnAbstract

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

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

4.00%

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

^[1]

Management fee

rr_ManagementFeesOverAssets

0.32%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.24%

Total annual operating expenses

rr_ExpensesOverAssets

0.81%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Class A and Class T purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class T purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 0.75% or 0.25%, respectively.

1 year

rr_ExpenseExampleYear01

479

3 years

rr_ExpenseExampleYear03

648

5 years

rr_ExpenseExampleYear05

832

10 years

rr_ExpenseExampleYear10

1,362

1 year

rr_ExpenseExampleNoRedemptionYear01

479

3 years

rr_ExpenseExampleNoRedemptionYear03

648

5 years

rr_ExpenseExampleNoRedemptionYear05

832

10 years

rr_ExpenseExampleNoRedemptionYear10

1,362

A T B C | Fidelity Investment Grade Bond Fund | Class B

Risk/Return:

rr_RiskReturnAbstract

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

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

5.00%

^[2]

Management fee

rr_ManagementFeesOverAssets

0.32%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.90%

Other expenses

rr_OtherExpensesOverAssets

0.28%

Total annual operating expenses

rr_ExpensesOverAssets

1.50%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Declines over 6 years from 5.00% to 0%.

1 year

rr_ExpenseExampleYear01

653

3 years

rr_ExpenseExampleYear03

774

5 years

rr_ExpenseExampleYear05

1,018

10 years

rr_ExpenseExampleYear10

1,504

1 year

rr_ExpenseExampleNoRedemptionYear01

153

3 years

rr_ExpenseExampleNoRedemptionYear03

474

5 years

rr_ExpenseExampleNoRedemptionYear05

818

10 years

rr_ExpenseExampleNoRedemptionYear10

1,504

A T B C | Fidelity Investment Grade Bond Fund | Class C

Risk/Return:

rr_RiskReturnAbstract

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

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[3]

Management fee

rr_ManagementFeesOverAssets

0.32%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.20%

Total annual operating expenses

rr_ExpensesOverAssets

1.52%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

On Class C shares redeemed less than one year after purchase.

1 year

rr_ExpenseExampleYear01

255

3 years

rr_ExpenseExampleYear03

480

5 years

rr_ExpenseExampleYear05

829

10 years

rr_ExpenseExampleYear10

1,813

1 year

rr_ExpenseExampleNoRedemptionYear01

155

3 years

rr_ExpenseExampleNoRedemptionYear03

480

5 years

rr_ExpenseExampleNoRedemptionYear05

829

10 years

rr_ExpenseExampleNoRedemptionYear10

1,813

A T B C | Fidelity Investment Grade Bond Fund | Return Before Taxes | Class A

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Class A - Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

3.40%

Past 5 years

rr_AverageAnnualReturnYear05

4.12%

Life of class

rr_AverageAnnualReturnSinceInception

4.33%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

Aug. 27, 2002

A T B C | Fidelity Investment Grade Bond Fund | Return Before Taxes | Class T

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Class T - Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

3.23%

Past 5 years

rr_AverageAnnualReturnYear05

4.06%

Life of class

rr_AverageAnnualReturnSinceInception

4.26%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

Aug. 27, 2002

A T B C | Fidelity Investment Grade Bond Fund | Return Before Taxes | Class B

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Class B - Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

1.92%

Past 5 years

rr_AverageAnnualReturnYear05

3.87%

Life of class

rr_AverageAnnualReturnSinceInception

4.20%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

Aug. 27, 2002

A T B C | Fidelity Investment Grade Bond Fund | Return Before Taxes | Class C

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Class C - Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

5.90%

Past 5 years

rr_AverageAnnualReturnYear05

4.17%

Life of class

rr_AverageAnnualReturnSinceInception

3.96%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

Aug. 27, 2002

A T B C | Fidelity Investment Grade Bond Fund | Return After Taxes on Distributions | Class A

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Class A - Return After Taxes on Distributions

Past 1 year

rr_AverageAnnualReturnYear01

2.35%

Past 5 years

rr_AverageAnnualReturnYear05

2.71%

Life of class

rr_AverageAnnualReturnSinceInception

2.79%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

Aug. 27, 2002

A T B C | Fidelity Investment Grade Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class A

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Class A - Return After Taxes on Distributions and Sale of Fund Shares

Past 1 year

rr_AverageAnnualReturnYear01

2.19%

Past 5 years

rr_AverageAnnualReturnYear05

2.66%

Life of class

rr_AverageAnnualReturnSinceInception

2.78%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

Aug. 27, 2002

A T B C | Fidelity Investment Grade Bond Fund | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Barclays^® U.S. Aggregate Bond Index

Past 1 year

rr_AverageAnnualReturnYear01

7.84%

Past 5 years

rr_AverageAnnualReturnYear05

6.50%

Life of class

rr_AverageAnnualReturnSinceInception

5.50%

^[4]

Inception Date

rr_AverageAnnualReturnInceptionDate

Aug. 27, 2002

[1] Class A and Class T purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class T purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 0.75% or 0.25%, respectively.

[2] Declines over 6 years from 5.00% to 0%.

[3] On Class C shares redeemed less than one year after purchase.

[4] From August 27, 2002.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SALEM STREET TRUST

Prospectus Date

rr_ProspectusDate

Oct. 30, 2012

F | Spartan U.S. Bond Index Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary

Fund/Class:
Spartan^® U.S. Bond Index Fund/F

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks to provide investment results that correspond to the aggregate price and interest performance of the debt securities in the Barclays^® U.S. Aggregate Bond Index.

Expense [Heading]

rr_ExpenseHeading

Fee Table

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees
(fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual class operating expenses
(expenses that you pay each year as a % 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 rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 100% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

100.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of the fund's assets in bonds included in the Barclays^® U.S. Aggregate Bond Index (the Index).
• Using statistical sampling techniques based on duration, maturity, interest rate sensitivity, security structure, and credit quality to attempt to replicate the returns of the Index using a smaller number of securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Entities located in foreign countries can be affected by adverse political, regulatory, market, or economic developments in those countries.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease.
• Correlation to Index. The performance of the fund and its index may vary somewhat due to factors such as transaction costs, sample selection, and timing differences associated with additions to and deletions from its index.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could 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 deposit of a bank 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 information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.401k.com and log in for updated return information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.401k.com and log in for updated return information

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) is not an indication of future performance.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Returns
Calendar Years

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	3.95%	September 30, 2011
Lowest Quarter Return	-1.37%	December 31, 2010
Year-to-Date Return	4.14%	September 30, 2012

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Returns

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

F | Spartan U.S. Bond Index Fund | Class F

Risk/Return:

rr_RiskReturnAbstract

Shareholder fees (fees paid directly from your investment)

rr_ShareholderFeeOther

none

Management fee

rr_ManagementFeesOverAssets

0.05%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

none

Total annual operating expenses

rr_ExpensesOverAssets

0.05%

1 year

rr_ExpenseExampleYear01

5

3 years

rr_ExpenseExampleYear03

16

5 years

rr_ExpenseExampleYear05

28

10 years

rr_ExpenseExampleYear10

64

2010

rr_AnnualReturn2010

6.49%

2011

rr_AnnualReturn2011

7.85%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2012

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

4.14%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2011

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

3.95%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2010

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(1.37%)

F | Spartan U.S. Bond Index Fund | Return Before Taxes | Class F

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Class F

Label

rr_AverageAnnualReturnLabel

Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

7.85%

Life of class

rr_AverageAnnualReturnSinceInception

6.46%

^[1]

F | Spartan U.S. Bond Index Fund | Return After Taxes on Distributions | Class F

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Class F

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions

Past 1 year

rr_AverageAnnualReturnYear01

6.56%

Life of class

rr_AverageAnnualReturnSinceInception

5.18%

^[1]

F | Spartan U.S. Bond Index Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class F

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Class F

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions and Sale of Fund Shares

Past 1 year

rr_AverageAnnualReturnYear01

5.16%

Life of class

rr_AverageAnnualReturnSinceInception

4.79%

^[1]

F | Spartan U.S. Bond Index Fund | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Barclays U.S. Aggregate Bond Index

Past 1 year

rr_AverageAnnualReturnYear01

7.84%

Life of class

rr_AverageAnnualReturnSinceInception

6.50%

^[1]

[1] From September 24, 2009.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SALEM STREET TRUST

Prospectus Date

rr_ProspectusDate

Oct. 30, 2012

Inst | Fidelity Corporate Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary

Fund/Class:
Fidelity^® Corporate Bond Fund/Fidelity Advisor^® Corporate Bond Fund Institutional

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks a high level of current income.

Expense [Heading]

rr_ExpenseHeading

Fee Table

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy, hold, or sell shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees
(fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual class operating expenses
(expenses that you pay each year as a % 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 rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 103% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

103.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of assets in investment-grade corporate bonds and other corporate debt securities and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Credit Bond Index.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Potentially investing in lower-quality debt securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could 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 deposit of a bank 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 information is intended to help you understand the risks of investing in the fund. The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.advisor.fidelity.com for updated return information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.advisor.fidelity.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) is not an indication of future performance.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Returns
Calendar Year

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the period shown in the chart:	Returns	Quarter ended
Highest Quarter Return	3.98%	September 30, 2011
Lowest Quarter Return	1.68%	March 31, 2011
Year-to-Date Return	8.81%	September 30, 2012

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Returns

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Inst | Fidelity Corporate Bond Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Shareholder fees (fees paid directly from your investment)

rr_ShareholderFeeOther

none

Management fee

rr_ManagementFeesOverAssets

0.35%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.14%

Total annual operating expenses

rr_ExpensesOverAssets

0.49%

1 year

rr_ExpenseExampleYear01

50

3 years

rr_ExpenseExampleYear03

157

5 years

rr_ExpenseExampleYear05

274

10 years

rr_ExpenseExampleYear10

616

2011

rr_AnnualReturn2011

11.06%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2012

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

8.81%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2011

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

3.98%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Mar. 31, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

1.68%

Inst | Fidelity Corporate Bond Fund | Return Before Taxes | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Institutional Class

Label

rr_AverageAnnualReturnLabel

Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

11.06%

Life of class

rr_AverageAnnualReturnSinceInception

10.09%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 04, 2010

Inst | Fidelity Corporate Bond Fund | Return After Taxes on Distributions | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Institutional Class

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions

Past 1 year

rr_AverageAnnualReturnYear01

9.36%

Life of class

rr_AverageAnnualReturnSinceInception

8.09%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 04, 2010

Inst | Fidelity Corporate Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Institutional Class

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions and Sale of Fund Shares

Past 1 year

rr_AverageAnnualReturnYear01

7.20%

Life of class

rr_AverageAnnualReturnSinceInception

7.39%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 04, 2010

Inst | Fidelity Corporate Bond Fund | Barclays U.S. Credit Bond Index (reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Barclays^® U.S. Credit Bond Index

Past 1 year

rr_AverageAnnualReturnYear01

8.35%

Life of class

rr_AverageAnnualReturnSinceInception

7.53%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 04, 2010

[1] From May 4, 2010.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SALEM STREET TRUST

Prospectus Date

rr_ProspectusDate

Oct. 30, 2012

F | Fidelity Series Investment Grade Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary

Fund/Class:
Fidelity^® Series Investment Grade Bond Fund/F

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks a high level of current income.

Expense [Heading]

rr_ExpenseHeading

Fee Table

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees
(fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual class operating expenses
(expenses that you pay each year as a % 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 rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 158% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

158.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Aggregate Bond Index.
• Allocating assets across different market sectors and maturities.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Potentially investing in lower-quality debt securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could 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 deposit of a bank 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 information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.401k.com and log in for updated return information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.401k.com and log in for updated return information

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) is not an indication of future performance.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Returns
Calendar Years

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the period shown in the chart:	Returns	Quarter ended
Highest Quarter Return	3.45%	September 30, 2011
Lowest Quarter Return	-0.94%	December 31, 2010
Year-to-Date Return	5.26%	September 30, 2012

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Returns

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

F | Fidelity Series Investment Grade Bond Fund | Class F

Risk/Return:

rr_RiskReturnAbstract

Shareholder fees (fees paid directly from your investment)

rr_ShareholderFeeOther

none

Management fee

rr_ManagementFeesOverAssets

0.35%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

none

Total annual operating expenses

rr_ExpensesOverAssets

0.35%

1 year

rr_ExpenseExampleYear01

36

3 years

rr_ExpenseExampleYear03

113

5 years

rr_ExpenseExampleYear05

197

10 years

rr_ExpenseExampleYear10

443

2010

rr_AnnualReturn2010

7.48%

2011

rr_AnnualReturn2011

7.94%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2012

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

5.26%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2011

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

3.45%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2010

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(0.94%)

F | Fidelity Series Investment Grade Bond Fund | Return Before Taxes | Class F

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Class F

Label

rr_AverageAnnualReturnLabel

Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

7.49%

Life of class

rr_AverageAnnualReturnSinceInception

8.81%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 26, 2009

F | Fidelity Series Investment Grade Bond Fund | Return After Taxes on Distributions | Class F

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Class F

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions

Past 1 year

rr_AverageAnnualReturnYear01

6.23%

Life of class

rr_AverageAnnualReturnSinceInception

6.79%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 26, 2009

F | Fidelity Series Investment Grade Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class F

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Class F

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions and Sale of Fund Shares

Past 1 year

rr_AverageAnnualReturnYear01

5.34%

Life of class

rr_AverageAnnualReturnSinceInception

6.42%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 26, 2009

F | Fidelity Series Investment Grade Bond Fund | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Barclays^® U.S. Aggregate Bond Index

Past 1 year

rr_AverageAnnualReturnYear01

7.84%

Life of class

rr_AverageAnnualReturnSinceInception

7.32%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 26, 2009

[1] From June 26, 2009.

XML

Retail | Fidelity Short-Term Bond Fund

Fund Summary

Fund/Class:
Fidelity^® Short-Term Bond Fund/Fidelity Short-Term Bond Fund

Investment Objective

The fund seeks to obtain a high level of current income consistent with preservation of capital.

Fee Table

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees (USD $)	Retail Fidelity Short-Term Bond Fund Class: Fidelity Short-Term Bond Fund
Shareholder fees (fees paid directly from your investment)	none

Annual class operating expenses
(expenses that you pay each year as a % of the value of your investment)

Annual Class Operating Expenses	Retail Fidelity Short-Term Bond Fund Class: Fidelity Short-Term Bond Fund
Management fee	0.32%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.13%
Total annual operating expenses	0.45%

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example (USD $)	Retail Fidelity Short-Term Bond Fund Class: Fidelity Short-Term Bond Fund
1 year	46
3 years	144
5 years	252
10 years	567

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 71% of the average value of its portfolio.

Principal Investment Strategies

• Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. 1-3 Year Government/Credit Bond Index.
• Normally maintaining a dollar-weighted average maturity of three years or less.
• Allocating assets across different market sectors and maturities.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Principal Investment Risks

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could lose money by investing in the fund.

Performance

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for updated return information.

Year-by-Year Returns
Calendar Years

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	2.95%	September 30, 2009
Lowest Quarter Return	-2.36%	December 31, 2008
Year-to-Date Return	2.13%	September 30, 2012

Average Annual Returns

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement. Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended
December 31, 2011

Average Annual Total Returns Retail Fidelity Short-Term Bond Fund	Past 1 year	Past 5 years	Past 10 years
Class: Fidelity Short-Term Bond Fund Return Before Taxes	1.78%	2.12%	2.94%
Class: Fidelity Short-Term Bond Fund Return After Taxes on Distributions	1.28%	1.06%	1.76%
Class: Fidelity Short-Term Bond Fund Return After Taxes on Distributions and Sale of Fund Shares	1.16%	1.18%	1.81%
Barclays U.S. 1-3 Year Government/Credit Bond Index (reflects no deduction for fees, expenses, or taxes)	1.59%	3.99%	3.63%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SALEM STREET TRUST

Prospectus Date

rr_ProspectusDate

Oct. 30, 2012

Inv Adv | Spartan U.S. Bond Index Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary

Fund/Class:
Spartan^® U.S. Bond Index Fund/Investor, Fidelity Advantage^®

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks to provide investment results that correspond to the aggregate price and interest performance of the debt securities in the Barclays^® U.S. Aggregate Bond Index.

Expense [Heading]

rr_ExpenseHeading

Fee Table

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees
(fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual class operating expenses
(expenses that you pay each year as a % 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 rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 100% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

100.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of the fund's assets in bonds included in the Barclays^® U.S. Aggregate Bond Index (the Index).
• Using statistical sampling techniques based on duration, maturity, interest rate sensitivity, security structure, and credit quality to attempt to replicate the returns of the Index using a smaller number of securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease
• Foreign Exposure. Entities located in foreign countries can be affected by adverse political, regulatory, market, or economic developments in those countries.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease.
• Correlation to Index. The performance of the fund and its index may vary somewhat due to factors such as transaction costs, sample selection, and timing differences associated with additions to and deletions from its index.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could 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 deposit of a bank 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 information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for updated return information.

Performance history will be available for Fidelity Advantage Class after Fidelity Advantage Class has been in operation for one calendar year.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.fidelity.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) is not an indication of future performance.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Returns
Calendar Years

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart for Investor Class:	Returns	Quarter ended
Highest Quarter Return	4.35%	September 30, 2002
Lowest Quarter Return	-2.56%	June 30, 2004
Year-to-Date Return	4.01%	September 30, 2012

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Returns

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for Investor Class are shown in the table below and after-tax returns for other classes will vary.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. After-tax returns for Investor Class are shown in the table below and after-tax returns for other classes will vary. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Inv Adv | Spartan U.S. Bond Index Fund | Investor Class

Risk/Return:

rr_RiskReturnAbstract

Annual index fund fee (for fund balances under $10,000)

rr_MaximumAccountFee

10.00

Management fee

rr_ManagementFeesOverAssets

0.05%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.17%

Total annual operating expenses

rr_ExpensesOverAssets

0.22%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

^[1]

Total annual operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1 year

rr_ExpenseExampleYear01

23

3 years

rr_ExpenseExampleYear03

71

5 years

rr_ExpenseExampleYear05

124

10 years

rr_ExpenseExampleYear10

280

2002

rr_AnnualReturn2002

10.22%

2003

rr_AnnualReturn2003

4.91%

2004

rr_AnnualReturn2004

4.36%

2005

rr_AnnualReturn2005

2.26%

2006

rr_AnnualReturn2006

4.33%

2007

rr_AnnualReturn2007

5.40%

2008

rr_AnnualReturn2008

3.76%

2009

rr_AnnualReturn2009

6.45%

2010

rr_AnnualReturn2010

6.29%

2011

rr_AnnualReturn2011

7.67%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2012

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

4.01%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2002

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

4.35%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Jun. 30, 2004

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(2.56%)

Inv Adv | Spartan U.S. Bond Index Fund | Fidelity Advantage Class

Risk/Return:

rr_RiskReturnAbstract

Annual index fund fee (for fund balances under $10,000)

rr_MaximumAccountFee

10.00

Management fee

rr_ManagementFeesOverAssets

0.05%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.12%

Total annual operating expenses

rr_ExpensesOverAssets

0.17%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.06%

^[1]

Total annual operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.11%

1 year

rr_ExpenseExampleYear01

11

3 years

rr_ExpenseExampleYear03

48

5 years

rr_ExpenseExampleYear05

89

10 years

rr_ExpenseExampleYear10

210

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

Performance history will be available for Fidelity Advantage Class after Fidelity Advantage Class has been in operation for one calendar year.

Inv Adv | Spartan U.S. Bond Index Fund | Return Before Taxes | Investor Class

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Investor Class - Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

7.67%

Past 5 years

rr_AverageAnnualReturnYear05

5.91%

Past 10 years

rr_AverageAnnualReturnYear10

5.54%

Inv Adv | Spartan U.S. Bond Index Fund | Return After Taxes on Distributions | Investor Class

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Investor Class - Return After Taxes on Distributions

Past 1 year

rr_AverageAnnualReturnYear01

6.45%

Past 5 years

rr_AverageAnnualReturnYear05

4.44%

Past 10 years

rr_AverageAnnualReturnYear10

3.92%

Inv Adv | Spartan U.S. Bond Index Fund | Return After Taxes on Distributions and Sale of Fund Shares | Investor Class

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Investor Class - Return After Taxes on Distributions and Sale of Fund Shares

Past 1 year

rr_AverageAnnualReturnYear01

5.04%

Past 5 years

rr_AverageAnnualReturnYear05

4.20%

Past 10 years

rr_AverageAnnualReturnYear10

3.80%

Inv Adv | Spartan U.S. Bond Index Fund | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Barclays U.S. Aggregate Bond Index

Past 1 year

rr_AverageAnnualReturnYear01

7.84%

Past 5 years

rr_AverageAnnualReturnYear05

6.50%

Past 10 years

rr_AverageAnnualReturnYear10

5.78%

[1] Fidelity Management & Research Company (FMR) has contractually agreed to reimburse Fidelity Advantage Class of the fund to the extent that total operating expenses (excluding interest, taxes, certain securities lending costs, brokerage commissions, extraordinary expenses, and acquired fund fees and expenses, if any), as a percentage of its respective average net assets, exceed 0.11%. This arrangement will remain in effect through October 31, 2013. FMR may not discontinue or modify this arrangement without the approval of the Board of Trustees.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SALEM STREET TRUST

Prospectus Date

rr_ProspectusDate

Oct. 30, 2012

Inst Adv Inst | Spartan U.S. Bond Index Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary

Fund/Class:
Spartan^® U.S. Bond Index Fund/Institutional, Fidelity Advantage^® Institutional

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks to provide investment results that correspond to the aggregate price and interest performance of the debt securities in the Barclays^® U.S. Aggregate Bond Index.

Expense [Heading]

rr_ExpenseHeading

Fee Table

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees
(fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual class operating expenses
(expenses that you pay each year as a % 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 rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 100% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

100.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of the fund's assets in bonds included in the Barclays^® U.S. Aggregate Bond Index (the Index).
• Using statistical sampling techniques based on duration, maturity, interest rate sensitivity, security structure, and credit quality to attempt to replicate the returns of the Index using a smaller number of securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Entities located in foreign countries can be affected by adverse political, regulatory, market, or economic developments in those countries.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease.
• Correlation to Index. The performance of the fund and its index may vary somewhat due to factors such as transaction costs, sample selection, and timing differences associated with additions to and deletions from its index.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could 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 deposit of a bank 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 information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance is not an indication of future performance.

Visit www.401k.com and log in for updated return information.

Performance history will be available for Institutional Class and Fidelity Advantage Institutional Class after Institutional Class and Fidelity Advantage Institutional Class have been in operation for one calendar year.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.401k.com and log in for updated return information

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance is not an indication of future performance.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Returns
Calendar Years

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	4.35%	September 30, 2002
Lowest Quarter Return	-2.56%	June 30, 2004
Year-to-Date Return	4.01%	September 30, 2012

Bar Chart, Returns for Class Not Offered in Prospectus [Text]

rr_BarChartReturnsForClassNotOfferedInProspectus

The returns shown above are for Investor Class, which is not offered through this prospectus. Institutional Class and Fidelity Advantage Institutional Class would have substantially similar annual returns to Investor Class because the classes are invested in the same portfolio of securities. Institutional Class's and Fidelity Advantage Institutional Class's returns would differ from Investor Class's returns to the extent that the classes do not have the same expenses.

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Returns

For the periods ended
December 31, 2011

Inst Adv Inst | Spartan U.S. Bond Index Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Shareholder fees (fees paid directly from your investment)

rr_ShareholderFeeOther

none

Management fee

rr_ManagementFeesOverAssets

0.05%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.02%

Total annual operating expenses

rr_ExpensesOverAssets

0.07%

1 year

rr_ExpenseExampleYear01

7

3 years

rr_ExpenseExampleYear03

23

5 years

rr_ExpenseExampleYear05

40

10 years

rr_ExpenseExampleYear10

90

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

Performance history will be available for Institutional Class and Fidelity Advantage Institutional Class after Institutional Class and Fidelity Advantage Institutional Class have been in operation for one calendar year.

Inst Adv Inst | Spartan U.S. Bond Index Fund | Investor Class

Risk/Return:

rr_RiskReturnAbstract

2002

rr_AnnualReturn2002

10.22%

^[1]

2003

rr_AnnualReturn2003

4.91%

^[1]

2004

rr_AnnualReturn2004

4.36%

^[1]

2005

rr_AnnualReturn2005

2.26%

^[1]

2006

rr_AnnualReturn2006

4.33%

^[1]

2007

rr_AnnualReturn2007

5.40%

^[1]

2008

rr_AnnualReturn2008

3.76%

^[1]

2009

rr_AnnualReturn2009

6.45%

^[1]

2010

rr_AnnualReturn2010

6.29%

^[1]

2011

rr_AnnualReturn2011

7.67%

^[1]

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2012

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

4.01%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2002

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

4.35%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Jun. 30, 2004

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(2.56%)

Label

rr_AverageAnnualReturnLabel

Spartan U.S. Bond Index Fund - Investor Class

^[1]

Past 1 year

rr_AverageAnnualReturnYear01

7.67%

^[1]

Past 5 years

rr_AverageAnnualReturnYear05

5.91%

^[1]

Past 10 years

rr_AverageAnnualReturnYear10

5.54%

^[1]

Inst Adv Inst | Spartan U.S. Bond Index Fund | Fidelity Advantage Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Shareholder fees (fees paid directly from your investment)

rr_ShareholderFeeOther

none

Management fee

rr_ManagementFeesOverAssets

0.05%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

none

Total annual operating expenses

rr_ExpensesOverAssets

0.05%

1 year

rr_ExpenseExampleYear01

5

3 years

rr_ExpenseExampleYear03

16

5 years

rr_ExpenseExampleYear05

28

10 years

rr_ExpenseExampleYear10

64

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

Performance history will be available for Institutional Class and Fidelity Advantage Institutional Class after Institutional Class and Fidelity Advantage Institutional Class have been in operation for one calendar year.

Inst Adv Inst | Spartan U.S. Bond Index Fund | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Barclays U.S. Aggregate Bond Index

Past 1 year

rr_AverageAnnualReturnYear01

7.84%

Past 5 years

rr_AverageAnnualReturnYear05

6.50%

Past 10 years

rr_AverageAnnualReturnYear10

5.78%

[1] The returns shown above are for Investor Class, which is not offered through this prospectus. Institutional Class and Fidelity Advantage Institutional Class would have substantially similar annual returns to Investor Class because the classes are invested in the same portfolio of securities. Institutional Class's and Fidelity Advantage Institutional Class's returns would differ from Investor Class's returns to the extent that the classes do not have the same expenses.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SALEM STREET TRUST

Prospectus Date

rr_ProspectusDate

Oct. 30, 2012

Retail | Fidelity Investment Grade Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary

Fund/Class:
Fidelity^® Investment Grade Bond Fund/Fidelity Investment Grade Bond Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks a high level of current income.

Expense [Heading]

rr_ExpenseHeading

Fee Table

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy, hold, or sell shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees
(fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual class operating expenses
(expenses that you pay each year as a % 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 rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 276% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

276.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Aggregate Bond Index.
• Allocating assets across different market sectors and maturities.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Potentially investing in lower-quality debt securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could 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 deposit of a bank 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 information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for updated return information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.fidelity.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) is not an indication of future performance.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Returns
Calendar Years

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	6.18%	September 30, 2009
Lowest Quarter Return	-3.41%	December 31, 2008
Year-to-Date Return	5.84%	September 30, 2012

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Returns

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Retail | Fidelity Investment Grade Bond Fund | Class: Fidelity Investment Grade Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Shareholder fees (fees paid directly from your investment)

rr_ShareholderFeeOther

none

Management fee

rr_ManagementFeesOverAssets

0.32%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.13%

Total annual operating expenses

rr_ExpensesOverAssets

0.45%

1 year

rr_ExpenseExampleYear01

46

3 years

rr_ExpenseExampleYear03

144

5 years

rr_ExpenseExampleYear05

252

10 years

rr_ExpenseExampleYear10

567

2002

rr_AnnualReturn2002

9.37%

2003

rr_AnnualReturn2003

4.67%

2004

rr_AnnualReturn2004

4.53%

2005

rr_AnnualReturn2005

2.73%

2006

rr_AnnualReturn2006

4.82%

2007

rr_AnnualReturn2007

2.59%

2008

rr_AnnualReturn2008

(7.12%)

2009

rr_AnnualReturn2009

16.02%

2010

rr_AnnualReturn2010

8.43%

2011

rr_AnnualReturn2011

7.91%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2012

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

5.84%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

6.18%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(3.41%)

Retail | Fidelity Investment Grade Bond Fund | Return Before Taxes | Class: Fidelity Investment Grade Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Investment Grade Bond Fund

Label

rr_AverageAnnualReturnLabel

Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

7.91%

Past 5 years

rr_AverageAnnualReturnYear05

5.29%

Past 10 years

rr_AverageAnnualReturnYear10

5.24%

Retail | Fidelity Investment Grade Bond Fund | Return After Taxes on Distributions | Class: Fidelity Investment Grade Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Investment Grade Bond Fund

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions

Past 1 year

rr_AverageAnnualReturnYear01

6.69%

Past 5 years

rr_AverageAnnualReturnYear05

3.74%

Past 10 years

rr_AverageAnnualReturnYear10

3.59%

Retail | Fidelity Investment Grade Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class: Fidelity Investment Grade Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Investment Grade Bond Fund

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions and Sale of Fund Shares

Past 1 year

rr_AverageAnnualReturnYear01

5.12%

Past 5 years

rr_AverageAnnualReturnYear05

3.58%

Past 10 years

rr_AverageAnnualReturnYear10

3.51%

Retail | Fidelity Investment Grade Bond Fund | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Barclays^® U.S. Aggregate Bond Index

Past 1 year

rr_AverageAnnualReturnYear01

7.84%

Past 5 years

rr_AverageAnnualReturnYear05

6.50%

Past 10 years

rr_AverageAnnualReturnYear10

5.78%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SALEM STREET TRUST

Prospectus Date

rr_ProspectusDate

Oct. 30, 2012

Inst | Fidelity Investment Grade Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary

Fund/Class:
Fidelity^® Investment Grade Bond Fund/Fidelity Advisor^® Investment Grade Bond Fund Institutional

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks a high level of current income.

Expense [Heading]

rr_ExpenseHeading

Fee Table

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy, hold, or sell shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees
(fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual class operating expenses
(expenses that you pay each year as a % 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 rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 276% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

276.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Aggregate Bond Index.
• Allocating assets across different market sectors and maturities.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Potentially investing in lower-quality debt securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could 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 deposit of a bank 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 information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.advisor.fidelity.com for updated return information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.advisor.fidelity.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) is not an indication of future performance.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Returns
Calendar Years

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	6.31%	September 30, 2009
Lowest Quarter Return	-3.42%	December 31, 2008
Year-to-Date Return	5.67%	September 30, 2012

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Returns

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Inst | Fidelity Investment Grade Bond Fund | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Shareholder fees (fees paid directly from your investment)

rr_ShareholderFeeOther

none

Management fee

rr_ManagementFeesOverAssets

0.32%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.18%

Total annual operating expenses

rr_ExpensesOverAssets

0.50%

1 year

rr_ExpenseExampleYear01

51

3 years

rr_ExpenseExampleYear03

160

5 years

rr_ExpenseExampleYear05

280

10 years

rr_ExpenseExampleYear10

628

2003

rr_AnnualReturn2003

4.88%

2004

rr_AnnualReturn2004

4.47%

2005

rr_AnnualReturn2005

2.71%

2006

rr_AnnualReturn2006

4.63%

2007

rr_AnnualReturn2007

2.70%

2008

rr_AnnualReturn2008

(7.16%)

2009

rr_AnnualReturn2009

15.76%

2010

rr_AnnualReturn2010

8.38%

2011

rr_AnnualReturn2011

8.00%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2012

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

5.67%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

6.31%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(3.42%)

Inst | Fidelity Investment Grade Bond Fund | Return Before Taxes | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Institutional Class

Label

rr_AverageAnnualReturnLabel

Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

8.00%

Past 5 years

rr_AverageAnnualReturnYear05

5.26%

Life of class

rr_AverageAnnualReturnSinceInception

5.05%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Aug. 27, 2002

Inst | Fidelity Investment Grade Bond Fund | Return After Taxes on Distributions | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Institutional Class

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions

Past 1 year

rr_AverageAnnualReturnYear01

6.80%

Past 5 years

rr_AverageAnnualReturnYear05

3.73%

Life of class

rr_AverageAnnualReturnSinceInception

3.42%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Aug. 27, 2002

Inst | Fidelity Investment Grade Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Institutional Class

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Institutional Class

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions and Sale of Fund Shares

Past 1 year

rr_AverageAnnualReturnYear01

5.17%

Past 5 years

rr_AverageAnnualReturnYear05

3.57%

Life of class

rr_AverageAnnualReturnSinceInception

3.36%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Aug. 27, 2002

Inst | Fidelity Investment Grade Bond Fund | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Barclays^® U.S. Aggregate Bond Index

Past 1 year

rr_AverageAnnualReturnYear01

7.84%

Past 5 years

rr_AverageAnnualReturnYear05

6.50%

Life of class

rr_AverageAnnualReturnSinceInception

5.50%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Aug. 27, 2002

[1] From August 27, 2002.

XML

Inst | Fidelity Investment Grade Bond Fund

Fund Summary

Fund/Class:
Fidelity^® Investment Grade Bond Fund/Fidelity Advisor^® Investment Grade Bond Fund Institutional

Investment Objective

The fund seeks a high level of current income.

Fee Table

The following table describes the fees and expenses that may be incurred when you buy, hold, or sell shares of the fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees (USD $)	Inst Fidelity Investment Grade Bond Fund Institutional Class
Shareholder fees (fees paid directly from your investment)	none

Annual class operating expenses
(expenses that you pay each year as a % of the value of your investment)

Annual Class Operating Expenses	Inst Fidelity Investment Grade Bond Fund Institutional Class
Management fee	0.32%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.18%
Total annual operating expenses	0.50%

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example (USD $)	Inst Fidelity Investment Grade Bond Fund Institutional Class
1 year	51
3 years	160
5 years	280
10 years	628

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 276% of the average value of its portfolio.

Principal Investment Strategies

• Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Aggregate Bond Index.
• Allocating assets across different market sectors and maturities.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Potentially investing in lower-quality debt securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Principal Investment Risks

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could lose money by investing in the fund.

Performance

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.advisor.fidelity.com for updated return information.

Year-by-Year Returns
Calendar Years

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	6.31%	September 30, 2009
Lowest Quarter Return	-3.42%	December 31, 2008
Year-to-Date Return	5.67%	September 30, 2012

Average Annual Returns

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Average Annual Total Returns Inst Fidelity Investment Grade Bond Fund	Past 1 year	Past 5 years	Life of class		Inception Date
Institutional Class Return Before Taxes	8.00%	5.26%	5.05%	[1]	Aug. 27, 2002
Institutional Class Return After Taxes on Distributions	6.80%	3.73%	3.42%	[1]	Aug. 27, 2002
Institutional Class Return After Taxes on Distributions and Sale of Fund Shares	5.17%	3.57%	3.36%	[1]	Aug. 27, 2002
Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)	7.84%	6.50%	5.50%	[1]	Aug. 27, 2002

[1] From August 27, 2002.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SALEM STREET TRUST

Prospectus Date

rr_ProspectusDate

Oct. 30, 2012

Retail | Fidelity Short-Term Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary

Fund/Class:
Fidelity^® Short-Term Bond Fund/Fidelity Short-Term Bond Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks to obtain a high level of current income consistent with preservation of capital.

Expense [Heading]

rr_ExpenseHeading

Fee Table

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees
(fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual class operating expenses
(expenses that you pay each year as a % 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 rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 71% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

71.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. 1-3 Year Government/Credit Bond Index.
• Normally maintaining a dollar-weighted average maturity of three years or less.
• Allocating assets across different market sectors and maturities.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could 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 deposit of a bank 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 information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for updated return information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.fidelity.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) is not an indication of future performance.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Returns
Calendar Years

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	2.95%	September 30, 2009
Lowest Quarter Return	-2.36%	December 31, 2008
Year-to-Date Return	2.13%	September 30, 2012

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Returns

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement. Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

For the periods ended
December 31, 2011

Retail | Fidelity Short-Term Bond Fund | Class: Fidelity Short-Term Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Shareholder fees (fees paid directly from your investment)

rr_ShareholderFeeOther

none

Management fee

rr_ManagementFeesOverAssets

0.32%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.13%

Total annual operating expenses

rr_ExpensesOverAssets

0.45%

1 year

rr_ExpenseExampleYear01

46

3 years

rr_ExpenseExampleYear03

144

5 years

rr_ExpenseExampleYear05

252

10 years

rr_ExpenseExampleYear10

567

2002

rr_AnnualReturn2002

6.71%

2003

rr_AnnualReturn2003

3.57%

2004

rr_AnnualReturn2004

1.86%

2005

rr_AnnualReturn2005

2.17%

2006

rr_AnnualReturn2006

4.58%

2007

rr_AnnualReturn2007

1.65%

2008

rr_AnnualReturn2008

(3.66%)

2009

rr_AnnualReturn2009

7.35%

2010

rr_AnnualReturn2010

3.79%

2011

rr_AnnualReturn2011

1.78%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2012

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

2.13%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

2.95%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(2.36%)

Retail | Fidelity Short-Term Bond Fund | Return Before Taxes | Class: Fidelity Short-Term Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Short-Term Bond Fund

Label

rr_AverageAnnualReturnLabel

Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

1.78%

Past 5 years

rr_AverageAnnualReturnYear05

2.12%

Past 10 years

rr_AverageAnnualReturnYear10

2.94%

Retail | Fidelity Short-Term Bond Fund | Return After Taxes on Distributions | Class: Fidelity Short-Term Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Short-Term Bond Fund

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions

Past 1 year

rr_AverageAnnualReturnYear01

1.28%

Past 5 years

rr_AverageAnnualReturnYear05

1.06%

Past 10 years

rr_AverageAnnualReturnYear10

1.76%

Retail | Fidelity Short-Term Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class: Fidelity Short-Term Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Short-Term Bond Fund

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions and Sale of Fund Shares

Past 1 year

rr_AverageAnnualReturnYear01

1.16%

Past 5 years

rr_AverageAnnualReturnYear05

1.18%

Past 10 years

rr_AverageAnnualReturnYear10

1.81%

Retail | Fidelity Short-Term Bond Fund | Barclays U.S. 1-3 Year Government/Credit Bond Index (reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Barclays^® U.S. 1-3 Year Government/Credit Bond Index

Past 1 year

rr_AverageAnnualReturnYear01

1.59%

Past 5 years

rr_AverageAnnualReturnYear05

3.99%

Past 10 years

rr_AverageAnnualReturnYear10

3.63%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SALEM STREET TRUST

Prospectus Date

rr_ProspectusDate

Oct. 30, 2012

Fidelity Intermediate Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary

Fund:
Fidelity^® Intermediate Bond Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks a high level of current income.

Expense [Heading]

rr_ExpenseHeading

Fee Table

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

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 % 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 rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 115% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

115.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Intermediate Government/Credit Bond Index.
• Normally maintaining a dollar-weighted average maturity between three and 10 years.
• Allocating assets across different market sectors and maturities.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could 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 deposit of a bank 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 information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for updated return information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.fidelity.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) is not an indication of future performance.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Returns
Calendar Years

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	7.00%	June 30, 2009
Lowest Quarter Return	-2.98%	September 30, 2008
Year-to-Date Return	4.42%	September 30, 2012

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Returns

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Fidelity Intermediate Bond Fund | Class: Fidelity Intermediate Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Shareholder fees (fees paid directly from your investment)

rr_ShareholderFeeOther

none

Management fee

rr_ManagementFeesOverAssets

0.32%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.13%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.45%

1 year

rr_ExpenseExampleYear01

46

3 years

rr_ExpenseExampleYear03

144

5 years

rr_ExpenseExampleYear05

252

10 years

rr_ExpenseExampleYear10

567

2002

rr_AnnualReturn2002

9.17%

2003

rr_AnnualReturn2003

4.96%

2004

rr_AnnualReturn2004

3.20%

2005

rr_AnnualReturn2005

1.75%

2006

rr_AnnualReturn2006

4.26%

2007

rr_AnnualReturn2007

3.96%

2008

rr_AnnualReturn2008

(5.84%)

2009

rr_AnnualReturn2009

17.13%

2010

rr_AnnualReturn2010

7.58%

2011

rr_AnnualReturn2011

6.15%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2012

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

4.42%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

7.00%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2008

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(2.98%)

Fidelity Intermediate Bond Fund | Return Before Taxes | Class: Fidelity Intermediate Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Intermediate Bond Fund

Label

rr_AverageAnnualReturnLabel

Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

6.15%

Past 5 years

rr_AverageAnnualReturnYear05

5.54%

Past 10 years

rr_AverageAnnualReturnYear10

5.09%

Fidelity Intermediate Bond Fund | Return After Taxes on Distributions | Class: Fidelity Intermediate Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Intermediate Bond Fund

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions

Past 1 year

rr_AverageAnnualReturnYear01

5.08%

Past 5 years

rr_AverageAnnualReturnYear05

3.99%

Past 10 years

rr_AverageAnnualReturnYear10

3.49%

Fidelity Intermediate Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class: Fidelity Intermediate Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Intermediate Bond Fund

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions and Sale of Fund Shares

Past 1 year

rr_AverageAnnualReturnYear01

3.98%

Past 5 years

rr_AverageAnnualReturnYear05

3.81%

Past 10 years

rr_AverageAnnualReturnYear10

3.41%

Fidelity Intermediate Bond Fund | Barclays U.S. Intermediate Government/Credit Bond Index (reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Intermediate Bond Fund

Label

rr_AverageAnnualReturnLabel

Barclays^® U.S. Intermediate Government/Credit Bond Index

Past 1 year

rr_AverageAnnualReturnYear01

5.80%

Past 5 years

rr_AverageAnnualReturnYear05

5.88%

Past 10 years

rr_AverageAnnualReturnYear10

5.20%

XML

Retail | Fidelity Conservative Income Bond Fund

Fund Summary

Fund/Class:
Fidelity^® Conservative Income Bond Fund/Fidelity Conservative Income Bond Fund

Investment Objective

The fund seeks to obtain a high level of current income consistent with preservation of capital.

Fee Table

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees (USD $)	Retail Fidelity Conservative Income Bond Fund Class: Fidelity Conservative Income Bond Fund
Shareholder fees (fees paid directly from your investment)	none

Annual class operating expenses
(expenses that you pay each year as a % of the value of your investment)

Annual Class Operating Expenses	Retail Fidelity Conservative Income Bond Fund Class: Fidelity Conservative Income Bond Fund
Management fee	0.30%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.10%
Total annual operating expenses	0.40%

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example (USD $)	Retail Fidelity Conservative Income Bond Fund Class: Fidelity Conservative Income Bond Fund
1 year	41
3 years	128
5 years	224
10 years	505

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 31% of the average value of its portfolio.

Principal Investment Strategies

• Normally investing at least 80% of assets in U.S. dollar-denominated money market and high quality investment-grade debt securities of all types, and repurchase agreements for those securities.
• Potentially entering into reverse repurchase agreements.
• Investing up to 5% of assets in lower quality investment-grade securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. 3-6 Month Treasury Bill Index.
• Normally maintaining a dollar-weighted average maturity of 0.75 years or less.
• Normally investing in fixed rate securities with a maximum maturity of two years or less and floating rate securities with a maximum maturity of three years or less.
• Allocating assets across different market sectors and maturities.
• Investing more than 25% of total assets in the financial services industries.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.

Principal Investment Risks

• Interest Rate Changes. Interest rate increases can cause the price of a debt or money market security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Financial Services Exposure. Changes in government regulation and interest rates and economic downturns can have a significant negative effect on issuers in the financial services sector, including the price of their securities or their ability to meet their payment obligations.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could lose money by investing in the fund.

Performance

Performance history will be available for the fund after the fund has been in operation for one calendar year.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	FIDELITY SALEM STREET TRUST
Prospectus Date	rr_ProspectusDate	Oct. 30, 2012
Retail | Fidelity Conservative Income Bond Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Summary Fund/Class: Fidelity® Conservative Income Bond Fund/Fidelity Conservative Income Bond Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The fund seeks to obtain a high level of current income consistent with preservation of capital.
Expense [Heading]	rr_ExpenseHeading	Fee Table
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual class operating expenses (expenses that you pay each year as a % 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 rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 31% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	31.00%
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds. Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Normally investing at least 80% of assets in U.S. dollar-denominated money market and high quality investment-grade debt securities of all types, and repurchase agreements for those securities. Potentially entering into reverse repurchase agreements. Investing up to 5% of assets in lower quality investment-grade securities. Managing the fund to have similar overall interest rate risk to the Barclays® U.S. 3-6 Month Treasury Bill Index. Normally maintaining a dollar-weighted average maturity of 0.75 years or less. Normally investing in fixed rate securities with a maximum maturity of two years or less and floating rate securities with a maximum maturity of three years or less. Allocating assets across different market sectors and maturities. Investing more than 25% of total assets in the financial services industries. Investing in domestic and foreign issuers. Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
Strategy Portfolio Concentration [Text]	rr_StrategyPortfolioConcentration	Investing more than 25% of total assets in the financial services industries.
Risk [Heading]	rr_RiskHeading	Principal Investment Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Interest Rate Changes. Interest rate increases can cause the price of a debt or money market security to decrease. Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market. Financial Services Exposure. Changes in government regulation and interest rates and economic downturns can have a significant negative effect on issuers in the financial services sector, including the price of their securities or their ability to meet their payment obligations. Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change. Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could 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 deposit of a bank 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 One Year or Less [Text]	rr_PerformanceOneYearOrLess	Performance history will be available for the fund after the fund has been in operation for one calendar year.
Retail | Fidelity Conservative Income Bond Fund | Class: Fidelity Conservative Income Bond Fund
Risk/Return:	rr_RiskReturnAbstract
Shareholder fees (fees paid directly from your investment)	rr_ShareholderFeeOther	none
Management fee	rr_ManagementFeesOverAssets	0.30%
Distribution and/or Service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.10%
Total annual operating expenses	rr_ExpensesOverAssets	0.40%
1 year	rr_ExpenseExampleYear01	41
3 years	rr_ExpenseExampleYear03	128
5 years	rr_ExpenseExampleYear05	224
10 years	rr_ExpenseExampleYear10	505

XML

F | Spartan U.S. Bond Index Fund

Fund Summary

Fund/Class:
Spartan^® U.S. Bond Index Fund/F

Investment Objective

The fund seeks to provide investment results that correspond to the aggregate price and interest performance of the debt securities in the Barclays^® U.S. Aggregate Bond Index.

Fee Table

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees (USD $)	F Spartan U.S. Bond Index Fund Class F
Shareholder fees (fees paid directly from your investment)	none

Annual class operating expenses
(expenses that you pay each year as a % of the value of your investment)

Annual Class Operating Expenses	F Spartan U.S. Bond Index Fund Class F
Management fee	0.05%
Distribution and/or Service (12b-1) fees	none
Other expenses	none
Total annual operating expenses	0.05%

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example (USD $)	F Spartan U.S. Bond Index Fund Class F
1 year	5
3 years	16
5 years	28
10 years	64

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 100% of the average value of its portfolio.

Principal Investment Strategies

• Normally investing at least 80% of the fund's assets in bonds included in the Barclays^® U.S. Aggregate Bond Index (the Index).
• Using statistical sampling techniques based on duration, maturity, interest rate sensitivity, security structure, and credit quality to attempt to replicate the returns of the Index using a smaller number of securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Principal Investment Risks

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Entities located in foreign countries can be affected by adverse political, regulatory, market, or economic developments in those countries.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease.
• Correlation to Index. The performance of the fund and its index may vary somewhat due to factors such as transaction costs, sample selection, and timing differences associated with additions to and deletions from its index.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could lose money by investing in the fund.

Performance

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.401k.com and log in for updated return information.

Year-by-Year Returns
Calendar Years

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	3.95%	September 30, 2011
Lowest Quarter Return	-1.37%	December 31, 2010
Year-to-Date Return	4.14%	September 30, 2012

Average Annual Returns

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Average Annual Total Returns F Spartan U.S. Bond Index Fund	Past 1 year	Life of class
Class F Return Before Taxes	7.85%	6.46%	[1]
Class F Return After Taxes on Distributions	6.56%	5.18%	[1]
Class F Return After Taxes on Distributions and Sale of Fund Shares	5.16%	4.79%	[1]
Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)	7.84%	6.50%	[1]

[1] From September 24, 2009.

XML

Inst | Fidelity Conservative Income Bond Fund

Fund Summary

Fund/Class:
Fidelity^® Conservative Income Bond Fund/Institutional

Investment Objective

The fund seeks to obtain a high level of current income consistent with preservation of capital.

Fee Table

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees (USD $)	Inst Fidelity Conservative Income Bond Fund Institutional Class
Shareholder fees (fees paid directly from your investment)	none

Annual class operating expenses
(expenses that you pay each year as a % of the value of your investment)

Annual Class Operating Expenses		Inst Fidelity Conservative Income Bond Fund Institutional Class
Management fee		0.30%
Distribution and/or Service (12b-1) fees		none
Other expenses		0.05%
Total annual operating expenses		0.35%
Fee waiver and/or expense reimbursement		0.05%
Total annual operating expenses after fee waiver and/or expense reimbursement	[1]	0.30%

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example (USD $)	Inst Fidelity Conservative Income Bond Fund Institutional Class
1 year	31
3 years	97
5 years	169
10 years	381

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 31% of the average value of its portfolio.

Principal Investment Strategies

• Normally investing at least 80% of assets in U.S. dollar-denominated money market and high quality investment-grade debt securities of all types, and repurchase agreements for those securities.
• Potentially entering into reverse repurchase agreements.
• Investing up to 5% of assets in lower quality investment-grade securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. 3-6 Month Treasury Bill Index.
• Normally maintaining a dollar-weighted average maturity of 0.75 years or less.
• Normally investing in fixed rate securities with a maximum maturity of two years or less and floating rate securities with a maximum maturity of three years or less.
• Allocating assets across different market sectors and maturities.
• Investing more than 25% of total assets in the financial services industries.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.

Principal Investment Risks

• Interest Rate Changes. Interest rate increases can cause the price of a debt or money market security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Financial Services Exposure. Changes in government regulation and interest rates and economic downturns can have a significant negative effect on issuers in the financial services sector, including the price of their securities or their ability to meet their payment obligations.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could lose money by investing in the fund.

Performance

Performance history will be available for the fund after the fund has been in operation for one calendar year.

[1] Fidelity Management & Research Company (FMR) has contractually agreed to reimburse Institutional Class of the fund to the extent that total operating expenses (excluding interest, taxes, certain securities lending costs, brokerage commissions, extraordinary expenses, and acquired fund fees and expenses, if any), as a percentage of its average net assets, exceed 0.30%. This arrangement will remain in effect for at least one year from the effective date of the prospectus. FMR may not discontinue or modify this arrangement without the approval of the Board of Trustees.

XML

Inv Adv | Spartan U.S. Bond Index Fund

Fund Summary

Fund/Class:
Spartan^® U.S. Bond Index Fund/Investor, Fidelity Advantage^®

Investment Objective

The fund seeks to provide investment results that correspond to the aggregate price and interest performance of the debt securities in the Barclays^® U.S. Aggregate Bond Index.

Fee Table

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees Inv Adv Spartan U.S. Bond Index Fund (USD $)	Investor Class	Fidelity Advantage Class
Annual index fund fee (for fund balances under $10,000)	10.00	10.00

Annual class operating expenses
(expenses that you pay each year as a % of the value of your investment)

Annual Class Operating Expenses Inv Adv Spartan U.S. Bond Index Fund		Investor Class	Fidelity Advantage Class
Management fee		0.05%	0.05%
Distribution and/or Service (12b-1) fees		none	none
Other expenses		0.17%	0.12%
Total annual operating expenses		0.22%	0.17%
Fee waiver and/or expense reimbursement	[1]		0.06%
Total annual operating expenses after fee waiver and/or expense reimbursement			0.11%

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example Inv Adv Spartan U.S. Bond Index Fund (USD $)	Investor Class	Fidelity Advantage Class
1 year	23	11
3 years	71	48
5 years	124	89
10 years	280	210

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 100% of the average value of its portfolio.

Principal Investment Strategies

• Normally investing at least 80% of the fund's assets in bonds included in the Barclays^® U.S. Aggregate Bond Index (the Index).
• Using statistical sampling techniques based on duration, maturity, interest rate sensitivity, security structure, and credit quality to attempt to replicate the returns of the Index using a smaller number of securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Principal Investment Risks

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease
• Foreign Exposure. Entities located in foreign countries can be affected by adverse political, regulatory, market, or economic developments in those countries.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease.
• Correlation to Index. The performance of the fund and its index may vary somewhat due to factors such as transaction costs, sample selection, and timing differences associated with additions to and deletions from its index.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could lose money by investing in the fund.

Performance

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for updated return information.

Performance history will be available for Fidelity Advantage Class after Fidelity Advantage Class has been in operation for one calendar year.

Year-by-Year Returns
Calendar Years

During the periods shown in the chart for Investor Class:	Returns	Quarter ended
Highest Quarter Return	4.35%	September 30, 2002
Lowest Quarter Return	-2.56%	June 30, 2004
Year-to-Date Return	4.01%	September 30, 2012

Average Annual Returns

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. After-tax returns for Investor Class are shown in the table below and after-tax returns for other classes will vary. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Average Annual Total Returns Inv Adv Spartan U.S. Bond Index Fund	Past 1 year	Past 5 years	Past 10 years
Investor Class Return Before Taxes	7.67%	5.91%	5.54%
Investor Class Return After Taxes on Distributions	6.45%	4.44%	3.92%
Investor Class Return After Taxes on Distributions and Sale of Fund Shares	5.04%	4.20%	3.80%
Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)	7.84%	6.50%	5.78%

[1] Fidelity Management & Research Company (FMR) has contractually agreed to reimburse Fidelity Advantage Class of the fund to the extent that total operating expenses (excluding interest, taxes, certain securities lending costs, brokerage commissions, extraordinary expenses, and acquired fund fees and expenses, if any), as a percentage of its respective average net assets, exceed 0.11%. This arrangement will remain in effect through October 31, 2013. FMR may not discontinue or modify this arrangement without the approval of the Board of Trustees.

XML

Document and Entity Information	12 Months Ended
	Oct. 30, 2012
Risk/Return:
Document Type	485BPOS
Document Period End Date	Aug. 31, 2012
Registrant Name	FIDELITY SALEM STREET TRUST
Central Index Key	0000035315
Amendment Flag	false
Document Creation Date	Oct. 29, 2012
Document Effective Date	Oct. 30, 2012
Prospectus Date	Oct. 30, 2012

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SALEM STREET TRUST

Prospectus Date

rr_ProspectusDate

Oct. 30, 2012

Retail | Fidelity Corporate Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary

Fund/Class:
Fidelity^® Corporate Bond Fund/Fidelity Corporate Bond Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks a high level of current income.

Expense [Heading]

rr_ExpenseHeading

Fee Table

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy, hold, or sell shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees
(fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual class operating expenses
(expenses that you pay each year as a % 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 rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 103% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

103.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of assets in investment-grade corporate bonds and other corporate debt securities and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Credit Bond Index.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Potentially investing in lower-quality debt securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could 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 deposit of a bank 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 information is intended to help you understand the risks of investing in the fund. The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for updated return information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.fidelity.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) is not an indication of future performance.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Returns
Calendar Year

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the period shown in the chart:	Returns	Quarter ended
Highest Quarter Return	4.00%	September 30, 2011
Lowest Quarter Return	1.68%	March 31, 2011
Year-to-Date Return	8.84%	September 30, 2012

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Returns

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Retail | Fidelity Corporate Bond Fund | Class: Fidelity Corporate Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Shareholder fees (fees paid directly from your investment)

rr_ShareholderFeeOther

none

Management fee

rr_ManagementFeesOverAssets

0.35%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.10%

Total annual operating expenses

rr_ExpensesOverAssets

0.45%

1 year

rr_ExpenseExampleYear01

46

3 years

rr_ExpenseExampleYear03

144

5 years

rr_ExpenseExampleYear05

252

10 years

rr_ExpenseExampleYear10

567

2011

rr_AnnualReturn2011

11.09%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2012

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

8.84%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2011

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

4.00%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Mar. 31, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

1.68%

Retail | Fidelity Corporate Bond Fund | Return Before Taxes | Class: Fidelity Corporate Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Corporate Bond Fund

Label

rr_AverageAnnualReturnLabel

Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

11.09%

Life of class

rr_AverageAnnualReturnSinceInception

10.09%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 04, 2010

Retail | Fidelity Corporate Bond Fund | Return After Taxes on Distributions | Class: Fidelity Corporate Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Corporate Bond Fund

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions

Past 1 year

rr_AverageAnnualReturnYear01

9.38%

Life of class

rr_AverageAnnualReturnSinceInception

8.09%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 04, 2010

Retail | Fidelity Corporate Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class: Fidelity Corporate Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Corporate Bond Fund

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions and Sale of Fund Shares

Past 1 year

rr_AverageAnnualReturnYear01

7.21%

Life of class

rr_AverageAnnualReturnSinceInception

7.39%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 04, 2010

Retail | Fidelity Corporate Bond Fund | Barclays U.S. Credit Bond Index (reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Barclays^® U.S. Credit Bond Index

Past 1 year

rr_AverageAnnualReturnYear01

8.35%

Life of class

rr_AverageAnnualReturnSinceInception

7.53%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 04, 2010

[1] From May 4, 2010.

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SALEM STREET TRUST

Prospectus Date

rr_ProspectusDate

Oct. 30, 2012

F | Fidelity Short-Term Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary

Fund/Class:
Fidelity^® Short-Term Bond Fund/F

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks to obtain a high level of current income consistent with preservation of capital.

Expense [Heading]

rr_ExpenseHeading

Fee Table

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees
(fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual class operating expenses
(expenses that you pay each year as a % 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 rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 71% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

71.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. 1-3 Year Government/Credit Bond Index.
• Normally maintaining a dollar-weighted average maturity of three years or less.
• Allocating assets across different market sectors and maturities.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could 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 deposit of a bank 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 information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.401k.com and log in for updated return information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.401k.com and log in for updated return information

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) is not an indication of future performance.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Returns
Calendar Years

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	1.38%	March 31, 2010
Lowest Quarter Return	-0.01%	December 31, 2010
Year-to-Date Return	2.09%	September 30, 2012

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Returns

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

F | Fidelity Short-Term Bond Fund | Class F

Risk/Return:

rr_RiskReturnAbstract

Shareholder fees (fees paid directly from your investment)

rr_ShareholderFeeOther

none

Management fee

rr_ManagementFeesOverAssets

0.32%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.03%

Total annual operating expenses

rr_ExpensesOverAssets

0.35%

1 year

rr_ExpenseExampleYear01

36

3 years

rr_ExpenseExampleYear03

113

5 years

rr_ExpenseExampleYear05

197

10 years

rr_ExpenseExampleYear10

443

2010

rr_AnnualReturn2010

4.02%

2011

rr_AnnualReturn2011

1.88%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2012

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

2.09%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2010

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

1.38%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2010

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(0.01%)

F | Fidelity Short-Term Bond Fund | Return Before Taxes | Class F

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Class F

Label

rr_AverageAnnualReturnLabel

Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

1.88%

Life of class

rr_AverageAnnualReturnSinceInception

3.94%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 26, 2009

F | Fidelity Short-Term Bond Fund | Return After Taxes on Distributions | Class F

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Class F

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions

Past 1 year

rr_AverageAnnualReturnYear01

1.35%

Life of class

rr_AverageAnnualReturnSinceInception

3.21%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 26, 2009

F | Fidelity Short-Term Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class F

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Class F

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions and Sale of Fund Shares

Past 1 year

rr_AverageAnnualReturnYear01

1.22%

Life of class

rr_AverageAnnualReturnSinceInception

2.94%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 26, 2009

F | Fidelity Short-Term Bond Fund | Barclays U.S. 1-3 Year Government/Credit Bond Index (reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Barclays^® U.S. 1-3 Year Government/Credit Bond Index

Past 1 year

rr_AverageAnnualReturnYear01

1.59%

Life of class

rr_AverageAnnualReturnSinceInception

2.47%

^[1]

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 26, 2009

[1] From June 26, 2009.

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Retail | Fidelity Corporate Bond Fund

Fund Summary

Fund/Class:
Fidelity^® Corporate Bond Fund/Fidelity Corporate Bond Fund

Investment Objective

The fund seeks a high level of current income.

Fee Table

The following table describes the fees and expenses that may be incurred when you buy, hold, or sell shares of the fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees (USD $)	Retail Fidelity Corporate Bond Fund Class: Fidelity Corporate Bond Fund
Shareholder fees (fees paid directly from your investment)	none

Annual class operating expenses
(expenses that you pay each year as a % of the value of your investment)

Annual Class Operating Expenses	Retail Fidelity Corporate Bond Fund Class: Fidelity Corporate Bond Fund
Management fee	0.35%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.10%
Total annual operating expenses	0.45%

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example (USD $)	Retail Fidelity Corporate Bond Fund Class: Fidelity Corporate Bond Fund
1 year	46
3 years	144
5 years	252
10 years	567

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 103% of the average value of its portfolio.

Principal Investment Strategies

• Normally investing at least 80% of assets in investment-grade corporate bonds and other corporate debt securities and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Credit Bond Index.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Potentially investing in lower-quality debt securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Principal Investment Risks

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could lose money by investing in the fund.

Performance

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for updated return information.

Year-by-Year Returns
Calendar Year

During the period shown in the chart:	Returns	Quarter ended
Highest Quarter Return	4.00%	September 30, 2011
Lowest Quarter Return	1.68%	March 31, 2011
Year-to-Date Return	8.84%	September 30, 2012

Average Annual Returns

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Average Annual Total Returns Retail Fidelity Corporate Bond Fund	Past 1 year	Life of class		Inception Date
Class: Fidelity Corporate Bond Fund Return Before Taxes	11.09%	10.09%	[1]	May 04, 2010
Class: Fidelity Corporate Bond Fund Return After Taxes on Distributions	9.38%	8.09%	[1]	May 04, 2010
Class: Fidelity Corporate Bond Fund Return After Taxes on Distributions and Sale of Fund Shares	7.21%	7.39%	[1]	May 04, 2010
Barclays U.S. Credit Bond Index (reflects no deduction for fees, expenses, or taxes)	8.35%	7.53%	[1]	May 04, 2010

[1] From May 4, 2010.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	FIDELITY SALEM STREET TRUST
Prospectus Date	rr_ProspectusDate	Oct. 30, 2012
Inst | Fidelity Conservative Income Bond Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Summary Fund/Class: Fidelity® Conservative Income Bond Fund/Institutional
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The fund seeks to obtain a high level of current income consistent with preservation of capital.
Expense [Heading]	rr_ExpenseHeading	Fee Table
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual class operating expenses (expenses that you pay each year as a % of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	at least one year from the effective date of the prospectus
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 rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 31% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	31.00%
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds. Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Normally investing at least 80% of assets in U.S. dollar-denominated money market and high quality investment-grade debt securities of all types, and repurchase agreements for those securities. Potentially entering into reverse repurchase agreements. Investing up to 5% of assets in lower quality investment-grade securities. Managing the fund to have similar overall interest rate risk to the Barclays® U.S. 3-6 Month Treasury Bill Index. Normally maintaining a dollar-weighted average maturity of 0.75 years or less. Normally investing in fixed rate securities with a maximum maturity of two years or less and floating rate securities with a maximum maturity of three years or less. Allocating assets across different market sectors and maturities. Investing more than 25% of total assets in the financial services industries. Investing in domestic and foreign issuers. Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
Strategy Portfolio Concentration [Text]	rr_StrategyPortfolioConcentration	Investing more than 25% of total assets in the financial services industries.
Risk [Heading]	rr_RiskHeading	Principal Investment Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Interest Rate Changes. Interest rate increases can cause the price of a debt or money market security to decrease. Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market. Financial Services Exposure. Changes in government regulation and interest rates and economic downturns can have a significant negative effect on issuers in the financial services sector, including the price of their securities or their ability to meet their payment obligations. Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change. Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could 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 deposit of a bank 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 One Year or Less [Text]	rr_PerformanceOneYearOrLess	Performance history will be available for the fund after the fund has been in operation for one calendar year.
Inst | Fidelity Conservative Income Bond Fund | Institutional Class
Risk/Return:	rr_RiskReturnAbstract
Shareholder fees (fees paid directly from your investment)	rr_ShareholderFeeOther	none
Management fee	rr_ManagementFeesOverAssets	0.30%
Distribution and/or Service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.05%
Total annual operating expenses	rr_ExpensesOverAssets	0.35%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.05%
Total annual operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.30%	[1]
1 year	rr_ExpenseExampleYear01	31
3 years	rr_ExpenseExampleYear03	97
5 years	rr_ExpenseExampleYear05	169
10 years	rr_ExpenseExampleYear10	381

[1] Fidelity Management & Research Company (FMR) has contractually agreed to reimburse Institutional Class of the fund to the extent that total operating expenses (excluding interest, taxes, certain securities lending costs, brokerage commissions, extraordinary expenses, and acquired fund fees and expenses, if any), as a percentage of its average net assets, exceed 0.30%. This arrangement will remain in effect for at least one year from the effective date of the prospectus. FMR may not discontinue or modify this arrangement without the approval of the Board of Trustees.

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A T C | Fidelity Corporate Bond Fund

Fund Summary

Fund/Class:
Fidelity^® Corporate Bond Fund/Fidelity Advisor^® Corporate Bond Fund A, T, C

Investment Objective

The fund seeks a high level of current income.

Fee Table

The following table describes the fees and expenses that may be incurred when you buy, hold, or sell shares of the fund.

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or certain other Fidelity funds. More information about these and other discounts is available from your investment professional and in the Fund Distribution section beginning on page (Click Here) of the prospectus.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees A T C Fidelity Corporate Bond Fund	Class A		Class T		Class C
Maximum sales charge (load) on purchases (as a % of offering price)	4.00%		4.00%		none
Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)	none	[1]	none	[1]	1.00%	[2]

Annual class operating expenses
(expenses that you pay each year as a % of the value of your investment)

Annual Class Operating Expenses A T C Fidelity Corporate Bond Fund	Class A	Class T	Class C
Management fee	0.35%	0.35%	0.35%
Distribution and/or Service (12b-1) fees	0.25%	0.25%	1.00%
Other expenses	0.16%	0.19%	0.16%
Total annual operating expenses	0.76%	0.79%	1.51%

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated and if you hold your shares:

Sell All Shares

Expense Example A T C Fidelity Corporate Bond Fund (USD $)	Class A	Class T	Class C
1 year	475	477	254
3 years	633	642	477
5 years	805	821	824
10 years	1,305	1,339	1,802

Hold Shares

Expense Example, No Redemption A T C Fidelity Corporate Bond Fund (USD $)	Class A	Class T	Class C
1 year	475	477	154
3 years	633	642	477
5 years	805	821	824
10 years	1,305	1,339	1,802

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 103% of the average value of its portfolio.

Principal Investment Strategies

• Normally investing at least 80% of assets in investment-grade corporate bonds and other corporate debt securities and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Credit Bond Index.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Potentially investing in lower-quality debt securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Principal Investment Risks

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could lose money by investing in the fund.

Performance

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.advisor.fidelity.com for updated return information.

Year-by-Year Returns

The returns in the bar chart do not reflect any applicable sales charges; if sales charges were reflected, returns would be lower than those shown.

Calendar Year

During the period shown in the chart for Class A:	Returns	Quarter ended
Highest Quarter Return	3.92%	September 30, 2011
Lowest Quarter Return	1.48%	March 31, 2011
Year-to-Date Return	8.59%	September 30, 2012

Average Annual Returns

Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges. After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Average Annual Total Returns A T C Fidelity Corporate Bond Fund	Past 1 year	Life of class		Inception Date
Class A Return Before Taxes	6.19%	7.08%	[1]	May 04, 2010
Class A Return After Taxes on Distributions	4.68%	5.26%	[1]	May 04, 2010
Class A Return After Taxes on Distributions and Sale of Fund Shares	4.04%	4.93%	[1]	May 04, 2010
Class T Return Before Taxes	6.27%	7.08%	[1]	May 04, 2010
Class C Return Before Taxes	8.90%	8.93%	[1]	May 04, 2010
Barclays U.S. Credit Bond Index (reflects no deduction for fees, expenses, or taxes)	8.35%	7.53%	[1]	May 04, 2010

[1] Class A and Class T purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class T purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 0.75% or 0.25%, respectively.

[2] On Class C shares redeemed less than one year after purchase.

[1] From May 4, 2010.

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F | Fidelity Short-Term Bond Fund

Fund Summary

Fund/Class:
Fidelity^® Short-Term Bond Fund/F

Investment Objective

The fund seeks to obtain a high level of current income consistent with preservation of capital.

Fee Table

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees (USD $)	F Fidelity Short-Term Bond Fund Class F
Shareholder fees (fees paid directly from your investment)	none

Annual class operating expenses
(expenses that you pay each year as a % of the value of your investment)

Annual Class Operating Expenses	F Fidelity Short-Term Bond Fund Class F
Management fee	0.32%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.03%
Total annual operating expenses	0.35%

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example (USD $)	F Fidelity Short-Term Bond Fund Class F
1 year	36
3 years	113
5 years	197
10 years	443

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 71% of the average value of its portfolio.

Principal Investment Strategies

• Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. 1-3 Year Government/Credit Bond Index.
• Normally maintaining a dollar-weighted average maturity of three years or less.
• Allocating assets across different market sectors and maturities.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Principal Investment Risks

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could lose money by investing in the fund.

Performance

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.401k.com and log in for updated return information.

Year-by-Year Returns
Calendar Years

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	1.38%	March 31, 2010
Lowest Quarter Return	-0.01%	December 31, 2010
Year-to-Date Return	2.09%	September 30, 2012

Average Annual Returns

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Average Annual Total Returns F Fidelity Short-Term Bond Fund	Past 1 year	Life of class		Inception Date
Class F Return Before Taxes	1.88%	3.94%	[1]	Jun. 26, 2009
Class F Return After Taxes on Distributions	1.35%	3.21%	[1]	Jun. 26, 2009
Class F Return After Taxes on Distributions and Sale of Fund Shares	1.22%	2.94%	[1]	Jun. 26, 2009
Barclays U.S. 1-3 Year Government/Credit Bond Index (reflects no deduction for fees, expenses, or taxes)	1.59%	2.47%	[1]	Jun. 26, 2009

[1] From June 26, 2009.

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Series | Fidelity Series Investment Grade Bond Fund

Fund Summary

Fund/Class:
Fidelity^® Series Investment Grade Bond Fund/Fidelity Series Investment Grade Bond Fund

Investment Objective

The fund seeks a high level of current income.

Fee Table

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees (USD $)	Series Fidelity Series Investment Grade Bond Fund Class: Fidelity Series Investment Grade Bond Fund
Shareholder fees (fees paid directly from your investment)	none

Annual class operating expenses
(expenses that you pay each year as a % of the value of your investment)

Annual Class Operating Expenses		Series Fidelity Series Investment Grade Bond Fund Class: Fidelity Series Investment Grade Bond Fund
Management fee		0.35%
Distribution and/or Service (12b-1) fees		none
Other expenses		0.11%
Total annual operating expenses		0.46%
Fee waiver and/or expense reimbursement	[1]	0.01%
Total annual operating expenses after fee waiver and/or expense reimbursement		0.45%

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example (USD $)	Series Fidelity Series Investment Grade Bond Fund Class: Fidelity Series Investment Grade Bond Fund
1 year	47
3 years	148
5 years	258
10 years	579

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 158% of the average value of its portfolio.

Principal Investment Strategies

• Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Aggregate Bond Index.
• Allocating assets across different market sectors and maturities.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Potentially investing in lower-quality debt securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Principal Investment Risks

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could lose money by investing in the fund.

Performance

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for updated return information.

Year-by-Year Returns
Calendar Years

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	5.40%	September 30, 2009
Lowest Quarter Return	-0.97%	December 31, 2010
Year-to-Date Return	5.19%	September 30, 2012

Average Annual Returns

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Average Annual Total Returns Series Fidelity Series Investment Grade Bond Fund	Past 1 year	Life of class		Inception Date
Class: Fidelity Series Investment Grade Bond Fund Return Before Taxes	7.75%	10.58%	[1]	Oct. 08, 2008
Class: Fidelity Series Investment Grade Bond Fund Return After Taxes on Distributions	6.08%	8.72%	[1]	Oct. 08, 2008
Class: Fidelity Series Investment Grade Bond Fund Return After Taxes on Distributions and Sale of Fund Shares	5.21%	8.06%	[1]	Oct. 08, 2008
Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)	7.84%	7.76%	[1]	Oct. 08, 2008

[1] Fidelity Management & Research Company (FMR) has contractually agreed to reimburse the class of shares of the fund to the extent that total operating expenses (excluding interest, taxes, certain securities lending costs, brokerage commissions, extraordinary expenses, and acquired fund fees and expenses, if any), as a percentage of its average net assets, exceed 0.45%. This arrangement will remain in effect for at least one year from the effective date of the prospectus. FMR may not discontinue or modify this arrangement without the approval of the Board of Trustees.

[1] From October 8, 2008.

XML

Fidelity Intermediate Bond Fund

Fund Summary

Fund:
Fidelity^® Intermediate Bond Fund

Investment Objective

The fund seeks a high level of current income.

Fee Table

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees (USD $)	Fidelity Intermediate Bond Fund Class: Fidelity Intermediate Bond Fund
Shareholder fees (fees paid directly from your investment)	none

Annual fund operating expenses
(expenses that you pay each year as a % of the value of your investment)

Annual Fund Operating Expenses	Fidelity Intermediate Bond Fund Class: Fidelity Intermediate Bond Fund
Management fee	0.32%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.13%
Total annual fund operating expenses	0.45%

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example (USD $)	Fidelity Intermediate Bond Fund Class: Fidelity Intermediate Bond Fund
1 year	46
3 years	144
5 years	252
10 years	567

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 115% of the average value of its portfolio.

Principal Investment Strategies

• Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Intermediate Government/Credit Bond Index.
• Normally maintaining a dollar-weighted average maturity between three and 10 years.
• Allocating assets across different market sectors and maturities.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Principal Investment Risks

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could lose money by investing in the fund.

Performance

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for updated return information.

Year-by-Year Returns
Calendar Years

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	7.00%	June 30, 2009
Lowest Quarter Return	-2.98%	September 30, 2008
Year-to-Date Return	4.42%	September 30, 2012

Average Annual Returns

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Average Annual Total Returns Fidelity Intermediate Bond Fund	Past 1 year	Past 5 years	Past 10 years
Class: Fidelity Intermediate Bond Fund Return Before Taxes	6.15%	5.54%	5.09%
Class: Fidelity Intermediate Bond Fund Return After Taxes on Distributions	5.08%	3.99%	3.49%
Class: Fidelity Intermediate Bond Fund Return After Taxes on Distributions and Sale of Fund Shares	3.98%	3.81%	3.41%
Barclays U.S. Intermediate Government/Credit Bond Index (reflects no deduction for fees, expenses, or taxes)	5.80%	5.88%	5.20%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SALEM STREET TRUST

Prospectus Date

rr_ProspectusDate

Oct. 30, 2012

A T C | Fidelity Corporate Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary

Fund/Class:
Fidelity^® Corporate Bond Fund/Fidelity Advisor^® Corporate Bond Fund A, T, C

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks a high level of current income.

Expense [Heading]

rr_ExpenseHeading

Fee Table

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy, hold, or sell shares of the fund.

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or certain other Fidelity funds. More information about these and other discounts is available from your investment professional and in the Fund Distribution section beginning on page (Click Here) of the prospectus.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees
(fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual class operating expenses
(expenses that you pay each year as a % 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 rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 103% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

103.00%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or certain other Fidelity funds.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

50,000

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated and if you hold your shares:

Expense Example by, Year, Caption [Text]

rr_ExpenseExampleByYearCaption

Sell All Shares

Expense Example, No Redemption, By Year, Caption [Text]

rr_ExpenseExampleNoRedemptionByYearCaption

Hold Shares

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of assets in investment-grade corporate bonds and other corporate debt securities and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Credit Bond Index.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Potentially investing in lower-quality debt securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could 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 deposit of a bank 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 information is intended to help you understand the risks of investing in the fund. The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.advisor.fidelity.com for updated return information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.advisor.fidelity.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) is not an indication of future performance.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Returns

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

The returns in the bar chart do not reflect any applicable sales charges; if sales charges were reflected, returns would be lower than those shown.

Calendar Year

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the period shown in the chart for Class A:	Returns	Quarter ended
Highest Quarter Return	3.92%	September 30, 2011
Lowest Quarter Return	1.48%	March 31, 2011
Year-to-Date Return	8.59%	September 30, 2012

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Returns

Performance Table Does Reflect Sales Loads

rr_PerformanceTableDoesReflectSalesLoads

Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges. After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

A T C | Fidelity Corporate Bond Fund | Class A

Risk/Return:

rr_RiskReturnAbstract

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

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

4.00%

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

^[1]

Management fee

rr_ManagementFeesOverAssets

0.35%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.16%

Total annual operating expenses

rr_ExpensesOverAssets

0.76%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Class A and Class T purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class T purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 0.75% or 0.25%, respectively.

1 year

rr_ExpenseExampleYear01

475

3 years

rr_ExpenseExampleYear03

633

5 years

rr_ExpenseExampleYear05

805

10 years

rr_ExpenseExampleYear10

1,305

1 year

rr_ExpenseExampleNoRedemptionYear01

475

3 years

rr_ExpenseExampleNoRedemptionYear03

633

5 years

rr_ExpenseExampleNoRedemptionYear05

805

10 years

rr_ExpenseExampleNoRedemptionYear10

1,305

2011

rr_AnnualReturn2011

10.62%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2012

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

8.59%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2011

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

3.92%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Mar. 31, 2011

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

1.48%

A T C | Fidelity Corporate Bond Fund | Class T

Risk/Return:

rr_RiskReturnAbstract

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

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

4.00%

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

none

^[1]

Management fee

rr_ManagementFeesOverAssets

0.35%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.19%

Total annual operating expenses

rr_ExpensesOverAssets

0.79%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Class A and Class T purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class T purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 0.75% or 0.25%, respectively.

1 year

rr_ExpenseExampleYear01

477

3 years

rr_ExpenseExampleYear03

642

5 years

rr_ExpenseExampleYear05

821

10 years

rr_ExpenseExampleYear10

1,339

1 year

rr_ExpenseExampleNoRedemptionYear01

477

3 years

rr_ExpenseExampleNoRedemptionYear03

642

5 years

rr_ExpenseExampleNoRedemptionYear05

821

10 years

rr_ExpenseExampleNoRedemptionYear10

1,339

A T C | Fidelity Corporate Bond Fund | Class C

Risk/Return:

rr_RiskReturnAbstract

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

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)

rr_MaximumDeferredSalesChargeOverOther

1.00%

^[2]

Management fee

rr_ManagementFeesOverAssets

0.35%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.16%

Total annual operating expenses

rr_ExpensesOverAssets

1.51%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

On Class C shares redeemed less than one year after purchase.

1 year

rr_ExpenseExampleYear01

254

3 years

rr_ExpenseExampleYear03

477

5 years

rr_ExpenseExampleYear05

824

10 years

rr_ExpenseExampleYear10

1,802

1 year

rr_ExpenseExampleNoRedemptionYear01

154

3 years

rr_ExpenseExampleNoRedemptionYear03

477

5 years

rr_ExpenseExampleNoRedemptionYear05

824

10 years

rr_ExpenseExampleNoRedemptionYear10

1,802

A T C | Fidelity Corporate Bond Fund | Return Before Taxes | Class A

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Class A - Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

6.19%

Life of class

rr_AverageAnnualReturnSinceInception

7.08%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 04, 2010

A T C | Fidelity Corporate Bond Fund | Return Before Taxes | Class T

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Class T - Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

6.27%

Life of class

rr_AverageAnnualReturnSinceInception

7.08%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 04, 2010

A T C | Fidelity Corporate Bond Fund | Return Before Taxes | Class C

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Class C - Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

8.90%

Life of class

rr_AverageAnnualReturnSinceInception

8.93%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 04, 2010

A T C | Fidelity Corporate Bond Fund | Return After Taxes on Distributions | Class A

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Class A - Return After Taxes on Distributions

Past 1 year

rr_AverageAnnualReturnYear01

4.68%

Life of class

rr_AverageAnnualReturnSinceInception

5.26%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 04, 2010

A T C | Fidelity Corporate Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class A

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Class A - Return After Taxes on Distributions and Sale of Fund Shares

Past 1 year

rr_AverageAnnualReturnYear01

4.04%

Life of class

rr_AverageAnnualReturnSinceInception

4.93%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 04, 2010

A T C | Fidelity Corporate Bond Fund | Barclays U.S. Credit Bond Index (reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Barclays^® U.S. Credit Bond Index

Past 1 year

rr_AverageAnnualReturnYear01

8.35%

Life of class

rr_AverageAnnualReturnSinceInception

7.53%

^[3]

Inception Date

rr_AverageAnnualReturnInceptionDate

May 04, 2010

[1] Class A and Class T purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class T purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 0.75% or 0.25%, respectively.

[2] On Class C shares redeemed less than one year after purchase.

[3] From May 4, 2010.

XML

Inst Adv Inst | Spartan U.S. Bond Index Fund

Fund Summary

Fund/Class:
Spartan^® U.S. Bond Index Fund/Institutional, Fidelity Advantage^® Institutional

Investment Objective

The fund seeks to provide investment results that correspond to the aggregate price and interest performance of the debt securities in the Barclays^® U.S. Aggregate Bond Index.

Fee Table

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees Inst Adv Inst Spartan U.S. Bond Index Fund (USD $)	Institutional Class	Fidelity Advantage Institutional Class
Shareholder fees (fees paid directly from your investment)	none	none

Annual class operating expenses
(expenses that you pay each year as a % of the value of your investment)

Annual Class Operating Expenses Inst Adv Inst Spartan U.S. Bond Index Fund	Institutional Class	Fidelity Advantage Institutional Class
Management fee	0.05%	0.05%
Distribution and/or Service (12b-1) fees	none	none
Other expenses	0.02%	none
Total annual operating expenses	0.07%	0.05%

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example Inst Adv Inst Spartan U.S. Bond Index Fund (USD $)	Institutional Class	Fidelity Advantage Institutional Class
1 year	7	5
3 years	23	16
5 years	40	28
10 years	90	64

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 100% of the average value of its portfolio.

Principal Investment Strategies

• Normally investing at least 80% of the fund's assets in bonds included in the Barclays^® U.S. Aggregate Bond Index (the Index).
• Using statistical sampling techniques based on duration, maturity, interest rate sensitivity, security structure, and credit quality to attempt to replicate the returns of the Index using a smaller number of securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Principal Investment Risks

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Entities located in foreign countries can be affected by adverse political, regulatory, market, or economic developments in those countries.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease.
• Correlation to Index. The performance of the fund and its index may vary somewhat due to factors such as transaction costs, sample selection, and timing differences associated with additions to and deletions from its index.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could lose money by investing in the fund.

Performance

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance is not an indication of future performance.

Visit www.401k.com and log in for updated return information.

Performance history will be available for Institutional Class and Fidelity Advantage Institutional Class after Institutional Class and Fidelity Advantage Institutional Class have been in operation for one calendar year.

Year-by-Year Returns
Calendar Years

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	4.35%	September 30, 2002
Lowest Quarter Return	-2.56%	June 30, 2004
Year-to-Date Return	4.01%	September 30, 2012

Average Annual Returns

For the periods ended
December 31, 2011

Average Annual Total Returns Inst Adv Inst Spartan U.S. Bond Index Fund		Past 1 year	Past 5 years	Past 10 years
Investor Class	[1]	7.67%	5.91%	5.54%
Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)		7.84%	6.50%	5.78%

[1] The returns shown above are for Investor Class, which is not offered through this prospectus. Institutional Class and Fidelity Advantage Institutional Class would have substantially similar annual returns to Investor Class because the classes are invested in the same portfolio of securities. Institutional Class's and Fidelity Advantage Institutional Class's returns would differ from Investor Class's returns to the extent that the classes do not have the same expenses.

[1] The returns shown above are for Investor Class, which is not offered through this prospectus. Institutional Class and Fidelity Advantage Institutional Class would have substantially similar annual returns to Investor Class because the classes are invested in the same portfolio of securities. Institutional Class's and Fidelity Advantage Institutional Class's returns would differ from Investor Class's returns to the extent that the classes do not have the same expenses.

XML

Retail | Fidelity Investment Grade Bond Fund

Fund Summary

Fund/Class:
Fidelity^® Investment Grade Bond Fund/Fidelity Investment Grade Bond Fund

Investment Objective

The fund seeks a high level of current income.

Fee Table

The following table describes the fees and expenses that may be incurred when you buy, hold, or sell shares of the fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees (USD $)	Retail Fidelity Investment Grade Bond Fund Class: Fidelity Investment Grade Bond Fund
Shareholder fees (fees paid directly from your investment)	none

Annual class operating expenses
(expenses that you pay each year as a % of the value of your investment)

Annual Class Operating Expenses	Retail Fidelity Investment Grade Bond Fund Class: Fidelity Investment Grade Bond Fund
Management fee	0.32%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.13%
Total annual operating expenses	0.45%

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example (USD $)	Retail Fidelity Investment Grade Bond Fund Class: Fidelity Investment Grade Bond Fund
1 year	46
3 years	144
5 years	252
10 years	567

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 276% of the average value of its portfolio.

Principal Investment Strategies

• Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Aggregate Bond Index.
• Allocating assets across different market sectors and maturities.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Potentially investing in lower-quality debt securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Principal Investment Risks

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could lose money by investing in the fund.

Performance

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for updated return information.

Year-by-Year Returns
Calendar Years

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	6.18%	September 30, 2009
Lowest Quarter Return	-3.41%	December 31, 2008
Year-to-Date Return	5.84%	September 30, 2012

Average Annual Returns

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Average Annual Total Returns Retail Fidelity Investment Grade Bond Fund	Past 1 year	Past 5 years	Past 10 years
Class: Fidelity Investment Grade Bond Fund Return Before Taxes	7.91%	5.29%	5.24%
Class: Fidelity Investment Grade Bond Fund Return After Taxes on Distributions	6.69%	3.74%	3.59%
Class: Fidelity Investment Grade Bond Fund Return After Taxes on Distributions and Sale of Fund Shares	5.12%	3.58%	3.51%
Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)	7.84%	6.50%	5.78%

XML

Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FIDELITY SALEM STREET TRUST

Prospectus Date

rr_ProspectusDate

Oct. 30, 2012

Series | Fidelity Series Investment Grade Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary

Fund/Class:
Fidelity^® Series Investment Grade Bond Fund/Fidelity Series Investment Grade Bond Fund

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks a high level of current income.

Expense [Heading]

rr_ExpenseHeading

Fee Table

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder fees
(fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual class operating expenses
(expenses that you pay each year as a % of the value of your investment)

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

at least one year from the effective date of the prospectus

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 rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 158% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

158.00%

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

• Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Aggregate Bond Index.
• Allocating assets across different market sectors and maturities.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Potentially investing in lower-quality debt securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could 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 deposit of a bank 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 information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.fidelity.com for updated return information.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.fidelity.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

Past performance (before and after taxes) is not an indication of future performance.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Returns
Calendar Years

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

During the periods shown in the chart:	Returns	Quarter ended
Highest Quarter Return	5.40%	September 30, 2009
Lowest Quarter Return	-0.97%	December 31, 2010
Year-to-Date Return	5.19%	September 30, 2012

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Returns

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Series | Fidelity Series Investment Grade Bond Fund | Class: Fidelity Series Investment Grade Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Shareholder fees (fees paid directly from your investment)

rr_ShareholderFeeOther

none

Management fee

rr_ManagementFeesOverAssets

0.35%

Distribution and/or Service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.11%

Total annual operating expenses

rr_ExpensesOverAssets

0.46%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.01%

^[1]

Total annual operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.45%

1 year

rr_ExpenseExampleYear01

47

3 years

rr_ExpenseExampleYear03

148

5 years

rr_ExpenseExampleYear05

258

10 years

rr_ExpenseExampleYear10

579

2009

rr_AnnualReturn2009

11.33%

2010

rr_AnnualReturn2010

7.38%

2011

rr_AnnualReturn2011

7.75%

Year to Date Return, Label

rr_YearToDateReturnLabel

Year-to-Date Return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Sep. 30, 2012

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

5.19%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarter Return

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

5.40%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarter Return

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2010

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(0.97%)

Series | Fidelity Series Investment Grade Bond Fund | Return Before Taxes | Class: Fidelity Series Investment Grade Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Series Investment Grade Bond Fund

Label

rr_AverageAnnualReturnLabel

Return Before Taxes

Past 1 year

rr_AverageAnnualReturnYear01

7.75%

Life of class

rr_AverageAnnualReturnSinceInception

10.58%

^[2]

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 08, 2008

Series | Fidelity Series Investment Grade Bond Fund | Return After Taxes on Distributions | Class: Fidelity Series Investment Grade Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Series Investment Grade Bond Fund

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions

Past 1 year

rr_AverageAnnualReturnYear01

6.08%

Life of class

rr_AverageAnnualReturnSinceInception

8.72%

^[2]

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 08, 2008

Series | Fidelity Series Investment Grade Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class: Fidelity Series Investment Grade Bond Fund

Risk/Return:

rr_RiskReturnAbstract

Column

rr_AverageAnnualReturnColumnName

Fidelity Series Investment Grade Bond Fund

Label

rr_AverageAnnualReturnLabel

Return After Taxes on Distributions and Sale of Fund Shares

Past 1 year

rr_AverageAnnualReturnYear01

5.21%

Life of class

rr_AverageAnnualReturnSinceInception

8.06%

^[2]

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 08, 2008

Series | Fidelity Series Investment Grade Bond Fund | Barclays U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)

Risk/Return:

rr_RiskReturnAbstract

Label

rr_AverageAnnualReturnLabel

Barclays^® U.S. Aggregate Bond Index

Past 1 year

rr_AverageAnnualReturnYear01

7.84%

Life of class

rr_AverageAnnualReturnSinceInception

7.76%

^[2]

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 08, 2008

[1] Fidelity Management & Research Company (FMR) has contractually agreed to reimburse the class of shares of the fund to the extent that total operating expenses (excluding interest, taxes, certain securities lending costs, brokerage commissions, extraordinary expenses, and acquired fund fees and expenses, if any), as a percentage of its average net assets, exceed 0.45%. This arrangement will remain in effect for at least one year from the effective date of the prospectus. FMR may not discontinue or modify this arrangement without the approval of the Board of Trustees.

[2] From October 8, 2008.

XML

Inst | Fidelity Corporate Bond Fund

Fund Summary

Fund/Class:
Fidelity^® Corporate Bond Fund/Fidelity Advisor^® Corporate Bond Fund Institutional

Investment Objective

The fund seeks a high level of current income.

Fee Table

The following table describes the fees and expenses that may be incurred when you buy, hold, or sell shares of the fund.

Shareholder fees
(fees paid directly from your investment)

Shareholder Fees (USD $)	Inst Fidelity Corporate Bond Fund Institutional Class
Shareholder fees (fees paid directly from your investment)	none

Annual class operating expenses
(expenses that you pay each year as a % of the value of your investment)

Annual Class Operating Expenses	Inst Fidelity Corporate Bond Fund Institutional Class
Management fee	0.35%
Distribution and/or Service (12b-1) fees	none
Other expenses	0.14%
Total annual operating expenses	0.49%

This example helps compare the cost of investing in the fund with the cost of investing in other mutual funds.

Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

Expense Example (USD $)	Inst Fidelity Corporate Bond Fund Institutional Class
1 year	50
3 years	157
5 years	274
10 years	616

Portfolio Turnover

The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 103% of the average value of its portfolio.

Principal Investment Strategies

• Normally investing at least 80% of assets in investment-grade corporate bonds and other corporate debt securities and repurchase agreements for those securities.
• Managing the fund to have similar overall interest rate risk to the Barclays^® U.S. Credit Bond Index.
• Investing in domestic and foreign issuers.
• Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
• Potentially investing in lower-quality debt securities.
• Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
• Investing in Fidelity's central funds (specialized investment vehicles used by Fidelity funds to invest in particular security types or investment disciplines).

Principal Investment Risks

• Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
• Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
• Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
• Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support or a maturity-shortening structure for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
• Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Unlike individual debt securities, which typically pay principal at maturity, the value of an investment in the fund will fluctuate. You could lose money by investing in the fund.

Performance

The following information is intended to help you understand the risks of investing in the fund. The information illustrates the performance of the fund's shares over the past year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the Additional Information about the Index section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

Visit www.advisor.fidelity.com for updated return information.

Year-by-Year Returns
Calendar Year

During the period shown in the chart:	Returns	Quarter ended
Highest Quarter Return	3.98%	September 30, 2011
Lowest Quarter Return	1.68%	March 31, 2011
Year-to-Date Return	8.81%	September 30, 2012

Average Annual Returns

After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.

For the periods ended
December 31, 2011

Average Annual Total Returns Inst Fidelity Corporate Bond Fund	Past 1 year	Life of class		Inception Date
Institutional Class Return Before Taxes	11.06%	10.09%	[1]	May 04, 2010
Institutional Class Return After Taxes on Distributions	9.36%	8.09%	[1]	May 04, 2010
Institutional Class Return After Taxes on Distributions and Sale of Fund Shares	7.20%	7.39%	[1]	May 04, 2010
Barclays U.S. Credit Bond Index (reflects no deduction for fees, expenses, or taxes)	8.35%	7.53%	[1]	May 04, 2010

[1] From May 4, 2010.