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Risk/Return:rr_RiskReturnAbstract 
Document Typedei_DocumentType485BPOS
Document Period End Datedei_DocumentPeriodEndDateAug. 31, 2011
Registrant Namedei_EntityRegistrantNameFIDELITY SALEM STREET TRUST
Central Index Keydei_EntityCentralIndexKey0000035315
Amendment Flagdei_AmendmentFlagfalse
Document Creation Datedei_DocumentCreationDateOct. 27, 2011
Document Effective Datedei_DocumentEffectiveDateOct. 29, 2011
Prospectus Daterr_ProspectusDateOct. 29, 2011
Fidelity Intermediate Bond Fund
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeading
Fund Summary
Fund:
Fidelity® Intermediate Bond Fund
Objective [Heading]rr_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks a high level of current income.
Fee Tablefsst35315_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFee Table
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThe following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionShareholder fees (fees paid directly from your investment)
Annual class operating expensesrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionAnnual fund operating expenses (expenses that you pay each year as a % of the value of your investment)
Expense Examplerr_ExpenseExampleAbstract 
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:

Portfolio Turnoverfsst35315_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 102% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate102.00%
Strategy [Heading]rr_StrategyHeadingPrincipal 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 Capital® 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) 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_RiskHeadingPrincipal 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 Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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.
Risk Lose Money [Text]rr_RiskLoseMoneyYou could lose money by investing in the fund.
Performancefsst35315_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPerformance
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_PerformanceInformationIllustratesVariabilityOfReturnsThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFuturePast performance (before and after taxes) is not an indication of future performance.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddresswww.fidelity.com
Annual Total Returnsrr_BarChartTableAbstract 
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 Return7.00%June 30, 2009
Lowest Quarter Return-2.98%September 30, 2008
Year-to-Date Return 5.17%September 30, 2011
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Performance Table Headingrr_PerformanceTableHeadingAverage Annual Returns
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-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, 2010
Performance Table Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredThe after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.
Fidelity Intermediate Bond Fund | Class: Fidelity Intermediate Bond Fund
 
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder fees (fees paid directly from your investment)rr_ShareholderFeeOther none
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.32%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets none
Other expensesrr_OtherExpensesOverAssets0.13%
Total annual operating expensesrr_ExpensesOverAssets0.45%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear0146
3 yearsrr_ExpenseExampleYear03144
5 yearsrr_ExpenseExampleYear05252
10 yearsrr_ExpenseExampleYear10567
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20018.83%
2002rr_AnnualReturn20029.17%
2003rr_AnnualReturn20034.96%
2004rr_AnnualReturn20043.20%
2005rr_AnnualReturn20051.75%
2006rr_AnnualReturn20064.26%
2007rr_AnnualReturn20073.96%
2008rr_AnnualReturn2008(5.84%)
2009rr_AnnualReturn200917.13%
2010rr_AnnualReturn20107.58%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn7.00%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(2.98%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateSep. 30, 2008
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn5.17%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Fidelity Intermediate Bond Fund | Return Before Taxes | Class: Fidelity Intermediate Bond Fund
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameFidelity Intermediate Bond Fund
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
Past 1 yearrr_AverageAnnualReturnYear017.58%
Past 5 yearsrr_AverageAnnualReturnYear055.16%
Past 10 yearsrr_AverageAnnualReturnYear105.35%
Fidelity Intermediate Bond Fund | Return After Taxes on Distributions | Class: Fidelity Intermediate Bond Fund
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameFidelity Intermediate Bond Fund
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
Past 1 yearrr_AverageAnnualReturnYear016.30%
Past 5 yearsrr_AverageAnnualReturnYear053.51%
Past 10 yearsrr_AverageAnnualReturnYear103.62%
Fidelity Intermediate Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class: Fidelity Intermediate Bond Fund
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameFidelity Intermediate Bond Fund
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares
Past 1 yearrr_AverageAnnualReturnYear014.92%
Past 5 yearsrr_AverageAnnualReturnYear053.42%
Past 10 yearsrr_AverageAnnualReturnYear103.55%
Fidelity Intermediate Bond Fund | Barclays Capital® U.S. Intermediate Government/Credit Bond Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital® U.S. Intermediate Government/Credit Bond Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for fees, expenses, or taxes)
Past 1 yearrr_AverageAnnualReturnYear015.89%
Past 5 yearsrr_AverageAnnualReturnYear055.53%
Past 10 yearsrr_AverageAnnualReturnYear105.51%
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_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks a high level of current income.
Fee Tablefsst35315_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFee Table
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThe following table describes the fees and expenses that may be incurred when you buy, hold, or sell shares of the fund.
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionShareholder fees (fees paid directly from your investment)
Annual class operating expensesrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionAnnual class operating expenses (expenses that you pay each year as a % of the value of your investment)
Expense Examplerr_ExpenseExampleAbstract 
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:

Portfolio Turnoverfsst35315_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio 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 242% of the average value of its portfolio.

Portfolio Turnover, Raterr_PortfolioTurnoverRate242.00%
Strategy [Heading]rr_StrategyHeadingPrincipal 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 Capital® 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) 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_RiskHeadingPrincipal 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) 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 Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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.
Risk Lose Money [Text]rr_RiskLoseMoneyYou could lose money by investing in the fund.
Performancefsst35315_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPerformance
Performance One Year or Less [Text]rr_PerformanceOneYearOrLessPerformance history will be available for the fund after the fund has been in operation for one calendar year.
Retail | Fidelity Corporate Bond Fund | Class: Fidelity Corporate Bond Fund
 
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder fees (fees paid directly from your investment)rr_ShareholderFeeOther none
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.35%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets none
Other expensesrr_OtherExpensesOverAssets0.10%
Total annual operating expensesrr_ExpensesOverAssets0.45%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear0146
3 yearsrr_ExpenseExampleYear03144
5 yearsrr_ExpenseExampleYear05252
10 yearsrr_ExpenseExampleYear10567
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_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks to obtain a high level of current income consistent with preservation of capital.
Fee Tablefsst35315_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFee Table
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThe following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionShareholder fees (fees paid directly from your investment)
Annual class operating expensesrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionAnnual class operating expenses (expenses that you pay each year as a % of the value of your investment)
Expense Examplerr_ExpenseExampleAbstract 
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:

Portfolio Turnoverfsst35315_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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. For the period from March 3, 2011 to August 31, 2011, the fund's portfolio turnover rate was 18% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate18.00%
Strategy [Heading]rr_StrategyHeadingPrincipal 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 Capital 3-6 Month U.S. 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_RiskHeadingPrincipal 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 Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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.
Risk Lose Money [Text]rr_RiskLoseMoneyYou could lose money by investing in the fund.
Performancefsst35315_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPerformance
Performance One Year or Less [Text]rr_PerformanceOneYearOrLessPerformance 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
 
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder fees (fees paid directly from your investment)rr_ShareholderFeeOther none
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.30%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets none
Other expensesrr_OtherExpensesOverAssets0.10%
Total annual operating expensesrr_ExpensesOverAssets0.40%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear0141
3 yearsrr_ExpenseExampleYear03128
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_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks a high level of current income.
Fee Tablefsst35315_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFee Table
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThe following table describes the fees and expenses that may be incurred when you buy, hold, or sell shares of the fund.
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionShareholder fees (fees paid directly from your investment)
Annual class operating expensesrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionAnnual class operating expenses (expenses that you pay each year as a % of the value of your investment)
Expense Examplerr_ExpenseExampleAbstract 
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:

Portfolio Turnoverfsst35315_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 275% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate275.00%
Strategy [Heading]rr_StrategyHeadingPrincipal 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 Capital® 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) 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_RiskHeadingPrincipal 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) 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 Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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.
Risk Lose Money [Text]rr_RiskLoseMoneyYou could lose money by investing in the fund.
Performancefsst35315_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPerformance
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_PerformanceInformationIllustratesVariabilityOfReturnsThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFuturePast performance (before and after taxes) is not an indication of future performance.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddresswww.fidelity.com
Annual Total Returnsrr_BarChartTableAbstract 
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 Return6.18%September 30, 2009
Lowest Quarter Return-3.41%December 31, 2008
Year-to-Date Return 6.62%September 30, 2011
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Performance Table Headingrr_PerformanceTableHeadingAverage Annual Returns
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-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, 2010
Performance Table Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredThe after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.
Retail | Fidelity Investment Grade Bond Fund | Class: Fidelity Investment Grade Bond Fund
 
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder fees (fees paid directly from your investment)rr_ShareholderFeeOther none
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.32%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets none
Other expensesrr_OtherExpensesOverAssets0.13%
Total annual operating expensesrr_ExpensesOverAssets0.45%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear0146
3 yearsrr_ExpenseExampleYear03144
5 yearsrr_ExpenseExampleYear05252
10 yearsrr_ExpenseExampleYear10567
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20018.54%
2002rr_AnnualReturn20029.37%
2003rr_AnnualReturn20034.67%
2004rr_AnnualReturn20044.53%
2005rr_AnnualReturn20052.73%
2006rr_AnnualReturn20064.82%
2007rr_AnnualReturn20072.59%
2008rr_AnnualReturn2008(7.12%)
2009rr_AnnualReturn200916.02%
2010rr_AnnualReturn20108.43%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn6.18%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateSep. 30, 2009
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(3.41%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn6.62%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Retail | Fidelity Investment Grade Bond Fund | Return Before Taxes | Class: Fidelity Investment Grade Bond Fund
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameFidelity Investment Grade Bond Fund
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
Past 1 yearrr_AverageAnnualReturnYear018.43%
Past 5 yearsrr_AverageAnnualReturnYear054.68%
Past 10 yearsrr_AverageAnnualReturnYear105.31%
Retail | Fidelity Investment Grade Bond Fund | Return After Taxes on Distributions | Class: Fidelity Investment Grade Bond Fund
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameFidelity Investment Grade Bond Fund
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
Past 1 yearrr_AverageAnnualReturnYear017.21%
Past 5 yearsrr_AverageAnnualReturnYear053.04%
Past 10 yearsrr_AverageAnnualReturnYear103.53%
Retail | Fidelity Investment Grade Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class: Fidelity Investment Grade Bond Fund
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameFidelity Investment Grade Bond Fund
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares
Past 1 yearrr_AverageAnnualReturnYear015.46%
Past 5 yearsrr_AverageAnnualReturnYear053.01%
Past 10 yearsrr_AverageAnnualReturnYear103.49%
Retail | Fidelity Investment Grade Bond Fund | Barclays Capital® U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital® U.S. Aggregate Bond Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for fees, expenses, or taxes)
Past 1 yearrr_AverageAnnualReturnYear016.54%
Past 5 yearsrr_AverageAnnualReturnYear055.80%
Past 10 yearsrr_AverageAnnualReturnYear105.84%
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_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks to obtain a high level of current income consistent with preservation of capital.
Fee Tablefsst35315_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFee Table
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThe following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionShareholder fees (fees paid directly from your investment)
Annual class operating expensesrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionAnnual class operating expenses (expenses that you pay each year as a % of the value of your investment)
Expense Examplerr_ExpenseExampleAbstract 
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:

Portfolio Turnoverfsst35315_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 223% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate223.00%
Strategy [Heading]rr_StrategyHeadingPrincipal 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 Capital® 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) 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_RiskHeadingPrincipal 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 Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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.
Risk Lose Money [Text]rr_RiskLoseMoneyYou could lose money by investing in the fund.
Performancefsst35315_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPerformance
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_PerformanceInformationIllustratesVariabilityOfReturnsThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFuturePast performance (before and after taxes) is not an indication of future performance.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddresswww.fidelity.com
Annual Total Returnsrr_BarChartTableAbstract 
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 Return3.10%September 30, 2001
Lowest Quarter Return-2.36%December 31, 2008
Year-to-Date Return 1.55%September 30, 2011
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Performance Table Headingrr_PerformanceTableHeadingAverage Annual Returns
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-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, 2010
Performance Table Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredThe 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 Higherrr_PerformanceTableExplanationAfterTaxHigherReturn 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.
Retail | Fidelity Short-Term Bond Fund | Class: Fidelity Short-Term Bond Fund
 
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder fees (fees paid directly from your investment)rr_ShareholderFeeOther none
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.32%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets none
Other expensesrr_OtherExpensesOverAssets0.13%
Total annual operating expensesrr_ExpensesOverAssets0.45%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear0146
3 yearsrr_ExpenseExampleYear03144
5 yearsrr_ExpenseExampleYear05252
10 yearsrr_ExpenseExampleYear10567
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20017.63%
2002rr_AnnualReturn20026.71%
2003rr_AnnualReturn20033.57%
2004rr_AnnualReturn20041.86%
2005rr_AnnualReturn20052.17%
2006rr_AnnualReturn20064.58%
2007rr_AnnualReturn20071.65%
2008rr_AnnualReturn2008(3.66%)
2009rr_AnnualReturn20097.35%
2010rr_AnnualReturn20103.79%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn3.10%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateSep. 30, 2001
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(2.36%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn1.55%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Retail | Fidelity Short-Term Bond Fund | Return Before Taxes | Class: Fidelity Short-Term Bond Fund
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameFidelity Short-Term Bond Fund
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
Past 1 yearrr_AverageAnnualReturnYear013.79%
Past 5 yearsrr_AverageAnnualReturnYear052.67%
Past 10 yearsrr_AverageAnnualReturnYear103.51%
Retail | Fidelity Short-Term Bond Fund | Return After Taxes on Distributions | Class: Fidelity Short-Term Bond Fund
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameFidelity Short-Term Bond Fund
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
Past 1 yearrr_AverageAnnualReturnYear013.09%
Past 5 yearsrr_AverageAnnualReturnYear051.40%
Past 10 yearsrr_AverageAnnualReturnYear102.17%
Retail | Fidelity Short-Term Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class: Fidelity Short-Term Bond Fund
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameFidelity Short-Term Bond Fund
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares
Past 1 yearrr_AverageAnnualReturnYear012.46%
Past 5 yearsrr_AverageAnnualReturnYear051.53%
Past 10 yearsrr_AverageAnnualReturnYear102.20%
Retail | Fidelity Short-Term Bond Fund | Barclays Capital® U.S. 1-3 Year Government/Credit Bond Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital® U.S. 1-3 Year Government/Credit Bond Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for fees, expenses, or taxes)
Past 1 yearrr_AverageAnnualReturnYear012.80%
Past 5 yearsrr_AverageAnnualReturnYear054.53%
Past 10 yearsrr_AverageAnnualReturnYear104.34%
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_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks a high level of current income.
Fee Tablefsst35315_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFee 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.

Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsYou 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_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionShareholder fees (fees paid directly from your investment)
Annual class operating expensesrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionAnnual class operating expenses (expenses that you pay each year as a % of the value of your investment)
Expense Examplerr_ExpenseExampleAbstract 
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_ExpenseExampleByYearCaptionSell All Shares
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionHold Shares
Portfolio Turnoverfsst35315_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 242% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate242.00%
Strategy [Heading]rr_StrategyHeadingPrincipal 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 Capital® 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) 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_RiskHeadingPrincipal 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) 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 Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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.
Risk Lose Money [Text]rr_RiskLoseMoneyYou could lose money by investing in the fund.
Performancefsst35315_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPerformance
Performance One Year or Less [Text]rr_PerformanceOneYearOrLessPerformance history will be available for the fund after the fund has been in operation for one calendar year.
A T C | Fidelity Corporate Bond Fund | Fidelity Corporate Bond Fund - Class A
 
Shareholder feesrr_ShareholderFeesAbstract 
Maximum sales charge (load) on purchases (as a % of offering price)rr_MaximumCumulativeSalesChargeOverOfferingPrice4.00%
Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none [1]
Expenses Deferred Charges [Text Block]rr_ExpensesDeferredChargesTextBlockClass 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.
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.35%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other expensesrr_OtherExpensesOverAssets0.15%
Total annual operating expensesrr_ExpensesOverAssets0.75%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01474
3 yearsrr_ExpenseExampleYear03630
5 yearsrr_ExpenseExampleYear05800
10 yearsrr_ExpenseExampleYear101,293
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01474
3 yearsrr_ExpenseExampleNoRedemptionYear03630
5 yearsrr_ExpenseExampleNoRedemptionYear05800
10 yearsrr_ExpenseExampleNoRedemptionYear101,293
A T C | Fidelity Corporate Bond Fund | Fidelity Corporate Bond Fund - Class T
 
Shareholder feesrr_ShareholderFeesAbstract 
Maximum sales charge (load) on purchases (as a % of offering price)rr_MaximumCumulativeSalesChargeOverOfferingPrice4.00%
Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none [1]
Expenses Deferred Charges [Text Block]rr_ExpensesDeferredChargesTextBlockClass 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.
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.35%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other expensesrr_OtherExpensesOverAssets0.15%
Total annual operating expensesrr_ExpensesOverAssets0.75%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01474
3 yearsrr_ExpenseExampleYear03630
5 yearsrr_ExpenseExampleYear05800
10 yearsrr_ExpenseExampleYear101,293
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01474
3 yearsrr_ExpenseExampleNoRedemptionYear03630
5 yearsrr_ExpenseExampleNoRedemptionYear05800
10 yearsrr_ExpenseExampleNoRedemptionYear101,293
A T C | Fidelity Corporate Bond Fund | Fidelity Corporate Bond Fund - Class C
 
Shareholder feesrr_ShareholderFeesAbstract 
Maximum sales charge (load) on purchases (as a % of offering price)rr_MaximumCumulativeSalesChargeOverOfferingPrice none
Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther1.00%[2]
Expenses Deferred Charges [Text Block]rr_ExpensesDeferredChargesTextBlockOn Class C shares redeemed less than one year after purchase.
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.35%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other expensesrr_OtherExpensesOverAssets0.12%
Total annual operating expensesrr_ExpensesOverAssets1.47%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01250
3 yearsrr_ExpenseExampleYear03465
5 yearsrr_ExpenseExampleYear05803
10 yearsrr_ExpenseExampleYear101,757
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01150
3 yearsrr_ExpenseExampleNoRedemptionYear03465
5 yearsrr_ExpenseExampleNoRedemptionYear05803
10 yearsrr_ExpenseExampleNoRedemptionYear101,757
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_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks a high level of current income.
Fee Tablefsst35315_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFee Table
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThe following table describes the fees and expenses that may be incurred when you buy, hold, or sell shares of the fund.
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionShareholder fees (fees paid directly from your investment)
Annual class operating expensesrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionAnnual class operating expenses (expenses that you pay each year as a % of the value of your investment)
Expense Examplerr_ExpenseExampleAbstract 
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:

Portfolio Turnoverfsst35315_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 242% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate242.00%
Strategy [Heading]rr_StrategyHeadingPrincipal 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 Capital® 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) 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_RiskHeadingPrincipal 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) 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 Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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.
Risk Lose Money [Text]rr_RiskLoseMoneyYou could lose money by investing in the fund.
Performancefsst35315_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPerformance
Performance One Year or Less [Text]rr_PerformanceOneYearOrLessPerformance history will be available for the fund after the fund has been in operation for one calendar year.
Inst | Fidelity Corporate Bond Fund | Fidelity Corporate Bond Fund - Institutional Class
 
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder fees (fees paid directly from your investment)rr_ShareholderFeeOther none
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.35%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets none
Other expensesrr_OtherExpensesOverAssets0.08%
Total annual operating expensesrr_ExpensesOverAssets0.43%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear0144
3 yearsrr_ExpenseExampleYear03138
5 yearsrr_ExpenseExampleYear05241
10 yearsrr_ExpenseExampleYear10542
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_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks to obtain a high level of current income consistent with preservation of capital.
Fee Tablefsst35315_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFee Table
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThe following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionShareholder fees (fees paid directly from your investment)
Annual class operating expensesrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionAnnual 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationat least one year from the effective date of the prospectus
Expense Examplerr_ExpenseExampleAbstract 
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:

Portfolio Turnoverfsst35315_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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. For the period from March 3, 2011 to August 31, 2011, the fund's portfolio turnover rate was 18% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate18.00%
Strategy [Heading]rr_StrategyHeadingPrincipal 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 Capital 3-6 Month U.S. 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_RiskHeadingPrincipal 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 Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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.
Risk Lose Money [Text]rr_RiskLoseMoneyYou could lose money by investing in the fund.
Performancefsst35315_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPerformance
Performance One Year or Less [Text]rr_PerformanceOneYearOrLessPerformance history will be available for the fund after the fund has been in operation for one calendar year.
Inst | Fidelity Conservative Income Bond Fund | Fidelity Conservative Income Bond Fund - Institutional Class
 
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder fees (fees paid directly from your investment)rr_ShareholderFeeOther none
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.30%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets none
Other expensesrr_OtherExpensesOverAssets0.05%
Total annual operating expensesrr_ExpensesOverAssets0.35%
Fee waiver and/or expense reimbursementrr_FeeWaiverOrReimbursementOverAssets0.05%
Total annual operating expenses after fee waiver and/or expense reimbursementrr_NetExpensesOverAssets0.30%[3]
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear0131
3 yearsrr_ExpenseExampleYear0397
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_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks a high level of current income.
Fee Tablefsst35315_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFee Table
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThe following table describes the fees and expenses that may be incurred when you buy, hold, or sell shares of the fund.
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionShareholder fees (fees paid directly from your investment)
Annual class operating expensesrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionAnnual class operating expenses (expenses that you pay each year as a % of the value of your investment)
Expense Examplerr_ExpenseExampleAbstract 
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:

Portfolio Turnoverfsst35315_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 275% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate275.00%
Strategy [Heading]rr_StrategyHeadingPrincipal 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 Capital® 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) 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_RiskHeadingPrincipal 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) 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 Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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.
Risk Lose Money [Text]rr_RiskLoseMoneyYou could lose money by investing in the fund.
Performancefsst35315_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPerformance
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_PerformanceInformationIllustratesVariabilityOfReturnsThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFuturePast performance (before and after taxes) is not an indication of future performance.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddresswww.advisor.fidelity.com
Annual Total Returnsrr_BarChartTableAbstract 
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 Return6.31%September 30, 2009
Lowest Quarter Return-3.42%December 31, 2008
Year-to-Date Return 6.58% September 30, 2011
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Performance Table Headingrr_PerformanceTableHeadingAverage Annual Returns
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-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, 2010
Performance Table Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredThe 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 Higherrr_PerformanceTableExplanationAfterTaxHigherReturn 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.
Inst | Fidelity Investment Grade Bond Fund | Fidelity Investment Grade Bond Fund - Institutional Class
 
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder fees (fees paid directly from your investment)rr_ShareholderFeeOther none
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.32%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets none
Other expensesrr_OtherExpensesOverAssets0.16%
Total annual operating expensesrr_ExpensesOverAssets0.48%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear0149
3 yearsrr_ExpenseExampleYear03154
5 yearsrr_ExpenseExampleYear05269
10 yearsrr_ExpenseExampleYear10604
Annual Total Returnsrr_BarChartTableAbstract 
2003rr_AnnualReturn20034.88%
2004rr_AnnualReturn20044.47%
2005rr_AnnualReturn20052.71%
2006rr_AnnualReturn20064.63%
2007rr_AnnualReturn20072.70%
2008rr_AnnualReturn2008(7.16%)
2009rr_AnnualReturn200915.76%
2010rr_AnnualReturn20108.38%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn6.31%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateSep. 30, 2009
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(3.42%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn6.58%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Inst | Fidelity Investment Grade Bond Fund | Return Before Taxes | Fidelity Investment Grade Bond Fund - Institutional Class
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameInstitutional Class
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
Past 1 yearrr_AverageAnnualReturnYear018.38%
Past 5 yearsrr_AverageAnnualReturnYear054.59%
Life of classrr_AverageAnnualReturnSinceInception4.70%[4]
Inception Daterr_AverageAnnualReturnInceptionDateAug. 27, 2002
Inst | Fidelity Investment Grade Bond Fund | Return After Taxes on Distributions | Fidelity Investment Grade Bond Fund - Institutional Class
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameInstitutional Class
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
Past 1 yearrr_AverageAnnualReturnYear017.18%
Past 5 yearsrr_AverageAnnualReturnYear052.97%
Life of classrr_AverageAnnualReturnSinceInception3.02%[4]
Inception Daterr_AverageAnnualReturnInceptionDateAug. 27, 2002
Inst | Fidelity Investment Grade Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Fidelity Investment Grade Bond Fund - Institutional Class
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameInstitutional Class
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares
Past 1 yearrr_AverageAnnualReturnYear015.43%
Past 5 yearsrr_AverageAnnualReturnYear052.95%
Life of classrr_AverageAnnualReturnSinceInception3.03%[4]
Inception Daterr_AverageAnnualReturnInceptionDateAug. 27, 2002
Inst | Fidelity Investment Grade Bond Fund | Barclays Capital® U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital® U.S. Aggregate Bond Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for fees, expenses, or taxes)
Past 1 yearrr_AverageAnnualReturnYear016.54%
Past 5 yearsrr_AverageAnnualReturnYear055.80%
Life of classrr_AverageAnnualReturnSinceInception5.23%[4]
Inception Daterr_AverageAnnualReturnInceptionDateAug. 27, 2002
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_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks a high level of current income.
Fee Tablefsst35315_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFee Table
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThe following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionShareholder fees (fees paid directly from your investment)
Annual class operating expensesrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionAnnual 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 Terminationrr_FeeWaiverOrReimbursementOverAssetsDateOfTerminationat least one year from the effective date of the prospectus
Expense Examplerr_ExpenseExampleAbstract 
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:

Portfolio Turnoverfsst35315_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 213% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate213.00%
Strategy [Heading]rr_StrategyHeadingPrincipal 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 Capital® 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) 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_RiskHeadingPrincipal 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) 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 Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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.
Risk Lose Money [Text]rr_RiskLoseMoneyYou could lose money by investing in the fund.
Performancefsst35315_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPerformance
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_PerformanceInformationIllustratesVariabilityOfReturnsThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFuturePast performance (before and after taxes) is not an indication of future performance.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddresswww.fidelity.com
Annual Total Returnsrr_BarChartTableAbstract 
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 Return5.40%September 30, 2009
Lowest Quarter Return-0.97%December 31, 2010
Year-to-Date Return 6.48%September 30, 2011
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Performance Table Headingrr_PerformanceTableHeadingAverage Annual Returns
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-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, 2010
Performance Table Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredThe after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.
Series | Fidelity Series Investment Grade Bond Fund | Class: Fidelity Series Investment Grade Bond Fund
 
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder fees (fees paid directly from your investment)rr_ShareholderFeeOther none
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.35%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets none
Other expensesrr_OtherExpensesOverAssets0.12%
Total annual operating expensesrr_ExpensesOverAssets0.47%
Fee waiver and/or expense reimbursementrr_FeeWaiverOrReimbursementOverAssets0.02%[5]
Total annual operating expenses after fee waiver and/or expense reimbursementrr_NetExpensesOverAssets0.45%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear0146
3 yearsrr_ExpenseExampleYear03144
5 yearsrr_ExpenseExampleYear05252
10 yearsrr_ExpenseExampleYear10567
Annual Total Returnsrr_BarChartTableAbstract 
2009rr_AnnualReturn200911.33%
2010rr_AnnualReturn20107.38%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn5.40%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateSep. 30, 2009
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(0.97%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2010
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn6.48%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Series | Fidelity Series Investment Grade Bond Fund | Return Before Taxes | Class: Fidelity Series Investment Grade Bond Fund
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameFidelity Series Investment Grade Bond Fund
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
Past 1 yearrr_AverageAnnualReturnYear017.38%
Life of classrr_AverageAnnualReturnSinceInception11.88%[6]
Inception Daterr_AverageAnnualReturnInceptionDateOct. 08, 2008
Series | Fidelity Series Investment Grade Bond Fund | Return After Taxes on Distributions | Class: Fidelity Series Investment Grade Bond Fund
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameFidelity Series Investment Grade Bond Fund
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
Past 1 yearrr_AverageAnnualReturnYear015.35%
Life of classrr_AverageAnnualReturnSinceInception9.93%[6]
Inception Daterr_AverageAnnualReturnInceptionDateOct. 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
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameFidelity Series Investment Grade Bond Fund
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares
Past 1 yearrr_AverageAnnualReturnYear015.04%
Life of classrr_AverageAnnualReturnSinceInception9.09%[6]
Inception Daterr_AverageAnnualReturnInceptionDateOct. 08, 2008
Series | Fidelity Series Investment Grade Bond Fund | Barclays Capital® U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital® U.S. Aggregate Bond Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for fees, expenses, or taxes)
Past 1 yearrr_AverageAnnualReturnYear016.54%
Life of classrr_AverageAnnualReturnSinceInception7.72%[6]
Inception Daterr_AverageAnnualReturnInceptionDateOct. 08, 2008
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_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks to obtain a high level of current income consistent with preservation of capital.
Fee Tablefsst35315_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFee Table
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThe following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionShareholder fees (fees paid directly from your investment)
Annual class operating expensesrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionAnnual class operating expenses (expenses that you pay each year as a % of the value of your investment)
Expense Examplerr_ExpenseExampleAbstract 
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:

Portfolio Turnoverfsst35315_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 223% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate223.00%
Strategy [Heading]rr_StrategyHeadingPrincipal 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 Capital® 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) 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_RiskHeadingPrincipal 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 Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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.
Risk Lose Money [Text]rr_RiskLoseMoneyYou could lose money by investing in the fund.
Performancefsst35315_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPerformance
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.401k.com and log in for updated return information.

Performance Information Illustrates Variability of Returns [Text]rr_PerformanceInformationIllustratesVariabilityOfReturnsThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFuturePast performance (before and after taxes) is not an indication of future performance.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddresswww.401k.com and log in for updated return information
Annual Total Returnsrr_BarChartTableAbstract 
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 Return1.38%March 31, 2010
Lowest Quarter Return-0.01%December 31, 2010
Year-to-Date Return 1.50%September 30, 2011
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Performance Table Headingrr_PerformanceTableHeadingAverage Annual Returns
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-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, 2010
Performance Table Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredThe after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.
F | Fidelity Short-Term Bond Fund | Fidelity Short-Term Bond Fund - Class F
 
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder fees (fees paid directly from your investment)rr_ShareholderFeeOther none
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.32%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets none
Other expensesrr_OtherExpensesOverAssets0.03%
Total annual operating expensesrr_ExpensesOverAssets0.35%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear0136
3 yearsrr_ExpenseExampleYear03113
5 yearsrr_ExpenseExampleYear05197
10 yearsrr_ExpenseExampleYear10443
Annual Total Returnsrr_BarChartTableAbstract 
2010rr_AnnualReturn20104.02%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn1.38%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateMar. 31, 2010
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(0.01%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2010
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn1.50%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
F | Fidelity Short-Term Bond Fund | Return Before Taxes | Fidelity Short-Term Bond Fund - Class F
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass F
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
Past 1 yearrr_AverageAnnualReturnYear014.02%
Life of classrr_AverageAnnualReturnSinceInception5.32%[7]
Inception Daterr_AverageAnnualReturnInceptionDateJun. 26, 2009
F | Fidelity Short-Term Bond Fund | Return After Taxes on Distributions | Fidelity Short-Term Bond Fund - Class F
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass F
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
Past 1 yearrr_AverageAnnualReturnYear013.28%
Life of classrr_AverageAnnualReturnSinceInception4.46%[7]
Inception Daterr_AverageAnnualReturnInceptionDateJun. 26, 2009
F | Fidelity Short-Term Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Fidelity Short-Term Bond Fund - Class F
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass F
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares
Past 1 yearrr_AverageAnnualReturnYear012.61%
Life of classrr_AverageAnnualReturnSinceInception4.03%[7]
Inception Daterr_AverageAnnualReturnInceptionDateJun. 26, 2009
F | Fidelity Short-Term Bond Fund | Barclays Capital® U.S. 1-3 Year Government/Credit Bond Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital® U.S. 1-3 Year Government/Credit Bond Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for fees, expenses, or taxes)
Past 1 yearrr_AverageAnnualReturnYear012.80%
Life of classrr_AverageAnnualReturnSinceInception3.05%[7]
Inception Daterr_AverageAnnualReturnInceptionDateJun. 26, 2009
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_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks a high level of current income.
Fee Tablefsst35315_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFee Table
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThe following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionShareholder fees (fees paid directly from your investment)
Annual class operating expensesrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionAnnual class operating expenses (expenses that you pay each year as a % of the value of your investment)
Expense Examplerr_ExpenseExampleAbstract 
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:

Portfolio Turnoverfsst35315_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 213% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate213.00%
Strategy [Heading]rr_StrategyHeadingPrincipal 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 Capital® 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) 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_RiskHeadingPrincipal 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) 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 Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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.
Risk Lose Money [Text]rr_RiskLoseMoneyYou could lose money by investing in the fund.
Performancefsst35315_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPerformance
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.401k.com and log in for updated return information.

Performance Information Illustrates Variability of Returns [Text]rr_PerformanceInformationIllustratesVariabilityOfReturnsThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFuturePast performance (before and after taxes) is not an indication of future performance.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddresswww.401k.com and log in for updated return information
Annual Total Returnsrr_BarChartTableAbstract 
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 Return3.29%June 30, 2010
Lowest Quarter Return-0.94%December 31, 2010
Year-to-Date Return 6.56%September 30, 2011
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Performance Table Headingrr_PerformanceTableHeadingAverage Annual Returns
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-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, 2010
Performance Table Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredThe after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.
F | Fidelity Series Investment Grade Bond Fund | Fidelity Series Investment Grade Bond Fund - Class F
 
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder fees (fees paid directly from your investment)rr_ShareholderFeeOther none
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.35%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets none
Other expensesrr_OtherExpensesOverAssets none
Total annual operating expensesrr_ExpensesOverAssets0.35%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear0136
3 yearsrr_ExpenseExampleYear03113
5 yearsrr_ExpenseExampleYear05197
10 yearsrr_ExpenseExampleYear10443
Annual Total Returnsrr_BarChartTableAbstract 
2010rr_AnnualReturn20107.48%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn3.29%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2010
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(0.94%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2010
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn6.56%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
F | Fidelity Series Investment Grade Bond Fund | Return Before Taxes | Fidelity Series Investment Grade Bond Fund - Class F
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass F
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
Past 1 yearrr_AverageAnnualReturnYear017.48%
Life of classrr_AverageAnnualReturnSinceInception9.39%[7]
Inception Daterr_AverageAnnualReturnInceptionDateJun. 26, 2009
F | Fidelity Series Investment Grade Bond Fund | Return After Taxes on Distributions | Fidelity Series Investment Grade Bond Fund - Class F
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass F
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
Past 1 yearrr_AverageAnnualReturnYear015.42%
Life of classrr_AverageAnnualReturnSinceInception7.16%[7]
Inception Daterr_AverageAnnualReturnInceptionDateJun. 26, 2009
F | Fidelity Series Investment Grade Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Fidelity Series Investment Grade Bond Fund - Class F
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass F
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares
Past 1 yearrr_AverageAnnualReturnYear015.11%
Life of classrr_AverageAnnualReturnSinceInception6.78%[7]
Inception Daterr_AverageAnnualReturnInceptionDateJun. 26, 2009
F | Fidelity Series Investment Grade Bond Fund | Barclays Capital® U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital® U.S. Aggregate Bond Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for fees, expenses, or taxes)
Past 1 yearrr_AverageAnnualReturnYear016.54%
Life of classrr_AverageAnnualReturnSinceInception6.98%[7]
Inception Daterr_AverageAnnualReturnInceptionDateJun. 26, 2009
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_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks to provide investment results that correspond to the aggregate price and interest performance of the debt securities in the Barclays Capital® U.S. Aggregate Bond Index.
Fee Tablefsst35315_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFee Table
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThe following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionShareholder fees (fees paid directly from your investment)
Annual class operating expensesrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionAnnual class operating expenses (expenses that you pay each year as a % of the value of your investment)
Expense Examplerr_ExpenseExampleAbstract 
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:

Portfolio Turnoverfsst35315_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 106% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate106.00%
Strategy [Heading]rr_StrategyHeadingPrincipal Investment Strategies
Strategy Narrative [Text Block]rr_StrategyNarrativeTextBlock
  • Normally investing at least 80% of the fund's assets in bonds included in the Barclays Capital® 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) 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_RiskHeadingPrincipal 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.
  • Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.
  • 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.

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 Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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.
Risk Lose Money [Text]rr_RiskLoseMoneyYou could lose money by investing in the fund.
Performancefsst35315_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPerformance
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.401k.com and log in for updated return information.

Performance Information Illustrates Variability of Returns [Text]rr_PerformanceInformationIllustratesVariabilityOfReturnsThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFuturePast performance (before and after taxes) is not an indication of future performance.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddresswww.401k.com and log in for updated return information
Annual Total Returnsrr_BarChartTableAbstract 
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 Return3.66%June 30, 2010
Lowest Quarter Return-1.37%December 31, 2010
Year-to-Date Return6.74%September 30, 2011
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Performance Table Headingrr_PerformanceTableHeadingAverage Annual Returns
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-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, 2010
Performance Table Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 Deferredrr_PerformanceTableNotRelevantToTaxDeferredThe after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.
F | Spartan U.S. Bond Index Fund | Spartan U.S. Bond Index Fund - Class F
 
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder fees (fees paid directly from your investment)rr_ShareholderFeeOther none
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.05%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets none
Other expensesrr_OtherExpensesOverAssets none
Total annual operating expensesrr_ExpensesOverAssets0.05%[8]
Expenses Restated to Reflect Current [Text]rr_ExpensesRestatedToReflectCurrentBased on historical expenses, adjusted to reflect current fees.
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear015
3 yearsrr_ExpenseExampleYear0316
5 yearsrr_ExpenseExampleYear0528
10 yearsrr_ExpenseExampleYear1064
Annual Total Returnsrr_BarChartTableAbstract 
2010rr_AnnualReturn20106.49%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn3.66%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2010
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(1.37%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2010
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn6.74%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
F | Spartan U.S. Bond Index Fund | Return Before Taxes | Spartan U.S. Bond Index Fund - Class F
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass F
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
Past 1 yearrr_AverageAnnualReturnYear016.49%
Life of classrr_AverageAnnualReturnSinceInception5.37%[9]
Inception Daterr_AverageAnnualReturnInceptionDateSep. 24, 2009
F | Spartan U.S. Bond Index Fund | Return After Taxes on Distributions | Spartan U.S. Bond Index Fund - Class F
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass F
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
Past 1 yearrr_AverageAnnualReturnYear015.23%
Life of classrr_AverageAnnualReturnSinceInception4.10%[9]
Inception Daterr_AverageAnnualReturnInceptionDateSep. 24, 2009
F | Spartan U.S. Bond Index Fund | Return After Taxes on Distributions and Sale of Fund Shares | Spartan U.S. Bond Index Fund - Class F
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameClass F
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares
Past 1 yearrr_AverageAnnualReturnYear014.35%
Life of classrr_AverageAnnualReturnSinceInception3.88%[9]
Inception Daterr_AverageAnnualReturnInceptionDateSep. 24, 2009
F | Spartan U.S. Bond Index Fund | Barclays Capital® U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital U.S. Aggregate Bond Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for fees, expenses, or taxes)
Past 1 yearrr_AverageAnnualReturnYear016.54%
Life of classrr_AverageAnnualReturnSinceInception5.45%[9]
Inception Daterr_AverageAnnualReturnInceptionDateSep. 24, 2009
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_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks a high level of current income.
Fee Tablefsst35315_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFee 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.

Expense Breakpoint Discounts [Text]rr_ExpenseBreakpointDiscountsYou 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_ExpenseBreakpointMinimumInvestmentRequiredAmount50,000
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionShareholder fees (fees paid directly from your investment)
Annual class operating expensesrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionAnnual class operating expenses (expenses that you pay each year as a % of the value of your investment)
Expense Examplerr_ExpenseExampleAbstract 
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_ExpenseExampleByYearCaptionSell All Shares
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
Expense Example, No Redemption, By Year, Caption [Text]rr_ExpenseExampleNoRedemptionByYearCaptionHold Shares
Portfolio Turnoverfsst35315_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 275% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate275.00%
Strategy [Heading]rr_StrategyHeadingPrincipal 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 Capital® 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) 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_RiskHeadingPrincipal 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) 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 Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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.
Risk Lose Money [Text]rr_RiskLoseMoneyYou could lose money by investing in the fund.
Performancefsst35315_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPerformance
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_PerformanceInformationIllustratesVariabilityOfReturnsThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFuturePast performance (before and after taxes) is not an indication of future performance.

Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddresswww.advisor.fidelity.com
Annual Total Returnsrr_BarChartTableAbstract 
Bar Chart [Heading]rr_BarChartHeadingYear-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 Return6.25%September 30, 2009
Lowest Quarter Return-3.49%December 31, 2008
Year-to-Date Return 6.37%September 30, 2011
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Performance Table Headingrr_PerformanceTableHeadingAverage Annual Returns
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockUnlike 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. 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, 2010
Performance Table Does Reflect Sales Loadsrr_PerformanceTableDoesReflectSalesLoadsUnlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges.
Performance Table Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 One Class of after Tax Shown [Text]rr_PerformanceTableOneClassOfAfterTaxShownAfter-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary.
Performance Table Not Relevant to Tax Deferredrr_PerformanceTableNotRelevantToTaxDeferredThe 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 Higherrr_PerformanceTableExplanationAfterTaxHigherReturn 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.
A T B C | Fidelity Investment Grade Bond Fund | Fidelity Investment Grade Bond Fund - Class A
 
Shareholder feesrr_ShareholderFeesAbstract 
Maximum sales charge (load) on purchases (as a % of offering price)rr_MaximumCumulativeSalesChargeOverOfferingPrice4.00%
Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none [1]
Expenses Deferred Charges [Text Block]rr_ExpensesDeferredChargesTextBlockClass 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.
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.32%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other expensesrr_OtherExpensesOverAssets0.21%
Total annual operating expensesrr_ExpensesOverAssets0.78%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01476
3 yearsrr_ExpenseExampleYear03639
5 yearsrr_ExpenseExampleYear05816
10 yearsrr_ExpenseExampleYear101,327
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01476
3 yearsrr_ExpenseExampleNoRedemptionYear03639
5 yearsrr_ExpenseExampleNoRedemptionYear05816
10 yearsrr_ExpenseExampleNoRedemptionYear101,327
Annual Total Returnsrr_BarChartTableAbstract 
2003rr_AnnualReturn20034.48%
2004rr_AnnualReturn20044.30%
2005rr_AnnualReturn20052.49%
2006rr_AnnualReturn20064.42%
2007rr_AnnualReturn20072.40%
2008rr_AnnualReturn2008(7.44%)
2009rr_AnnualReturn200915.49%
2010rr_AnnualReturn20108.10%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn6.25%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateSep. 30, 2009
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(3.49%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn6.37%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
A T B C | Fidelity Investment Grade Bond Fund | Fidelity Investment Grade Bond Fund - Class T
 
Shareholder feesrr_ShareholderFeesAbstract 
Maximum sales charge (load) on purchases (as a % of offering price)rr_MaximumCumulativeSalesChargeOverOfferingPrice4.00%
Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none [1]
Expenses Deferred Charges [Text Block]rr_ExpensesDeferredChargesTextBlockClass 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.
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.32%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other expensesrr_OtherExpensesOverAssets0.24%
Total annual operating expensesrr_ExpensesOverAssets0.81%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01479
3 yearsrr_ExpenseExampleYear03648
5 yearsrr_ExpenseExampleYear05832
10 yearsrr_ExpenseExampleYear101,362
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01479
3 yearsrr_ExpenseExampleNoRedemptionYear03648
5 yearsrr_ExpenseExampleNoRedemptionYear05832
10 yearsrr_ExpenseExampleNoRedemptionYear101,362
A T B C | Fidelity Investment Grade Bond Fund | Fidelity Investment Grade Bond Fund - Class B
 
Shareholder feesrr_ShareholderFeesAbstract 
Maximum sales charge (load) on purchases (as a % of offering price)rr_MaximumCumulativeSalesChargeOverOfferingPrice none
Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther5.00%[10]
Expenses Deferred Charges [Text Block]rr_ExpensesDeferredChargesTextBlockDeclines over 6 years from 5.00% to 0%.
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.32%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets0.90%
Other expensesrr_OtherExpensesOverAssets0.29%
Total annual operating expensesrr_ExpensesOverAssets1.51%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01654
3 yearsrr_ExpenseExampleYear03777
5 yearsrr_ExpenseExampleYear051,024
10 yearsrr_ExpenseExampleYear101,512
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01154
3 yearsrr_ExpenseExampleNoRedemptionYear03477
5 yearsrr_ExpenseExampleNoRedemptionYear05824
10 yearsrr_ExpenseExampleNoRedemptionYear101,512
A T B C | Fidelity Investment Grade Bond Fund | Fidelity Investment Grade Bond Fund - Class C
 
Shareholder feesrr_ShareholderFeesAbstract 
Maximum sales charge (load) on purchases (as a % of offering price)rr_MaximumCumulativeSalesChargeOverOfferingPrice none
Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther1.00%[2]
Expenses Deferred Charges [Text Block]rr_ExpensesDeferredChargesTextBlockOn Class C shares redeemed less than one year after purchase.
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.32%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets1.00%
Other expensesrr_OtherExpensesOverAssets0.21%
Total annual operating expensesrr_ExpensesOverAssets1.53%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01256
3 yearsrr_ExpenseExampleYear03483
5 yearsrr_ExpenseExampleYear05834
10 yearsrr_ExpenseExampleYear101,824
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01156
3 yearsrr_ExpenseExampleNoRedemptionYear03483
5 yearsrr_ExpenseExampleNoRedemptionYear05834
10 yearsrr_ExpenseExampleNoRedemptionYear101,824
A T B C | Fidelity Investment Grade Bond Fund | Return Before Taxes | Fidelity Investment Grade Bond Fund - Class A
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass A - Return Before Taxes
Past 1 yearrr_AverageAnnualReturnYear013.77%
Past 5 yearsrr_AverageAnnualReturnYear053.47%
Life of classrr_AverageAnnualReturnSinceInception3.93%[4]
Inception Daterr_AverageAnnualReturnInceptionDateAug. 27, 2002
A T B C | Fidelity Investment Grade Bond Fund | Return Before Taxes | Fidelity Investment Grade Bond Fund - Class T
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass T - Return Before Taxes
Past 1 yearrr_AverageAnnualReturnYear013.73%
Past 5 yearsrr_AverageAnnualReturnYear053.46%
Life of classrr_AverageAnnualReturnSinceInception3.87%[4]
Inception Daterr_AverageAnnualReturnInceptionDateAug. 27, 2002
A T B C | Fidelity Investment Grade Bond Fund | Return Before Taxes | Fidelity Investment Grade Bond Fund - Class B
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass B - Return Before Taxes
Past 1 yearrr_AverageAnnualReturnYear012.29%
Past 5 yearsrr_AverageAnnualReturnYear053.23%
Life of classrr_AverageAnnualReturnSinceInception3.79%[4]
Inception Daterr_AverageAnnualReturnInceptionDateAug. 27, 2002
A T B C | Fidelity Investment Grade Bond Fund | Return Before Taxes | Fidelity Investment Grade Bond Fund - Class C
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass C - Return Before Taxes
Past 1 yearrr_AverageAnnualReturnYear016.28%
Past 5 yearsrr_AverageAnnualReturnYear053.53%
Life of classrr_AverageAnnualReturnSinceInception3.61%[4]
Inception Daterr_AverageAnnualReturnInceptionDateAug. 27, 2002
A T B C | Fidelity Investment Grade Bond Fund | Return After Taxes on Distributions | Fidelity Investment Grade Bond Fund - Class A
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass A - Return After Taxes on Distributions
Past 1 yearrr_AverageAnnualReturnYear012.72%
Past 5 yearsrr_AverageAnnualReturnYear051.96%
Life of classrr_AverageAnnualReturnSinceInception2.35%[4]
Inception Daterr_AverageAnnualReturnInceptionDateAug. 27, 2002
A T B C | Fidelity Investment Grade Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Fidelity Investment Grade Bond Fund - Class A
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass A - Return After Taxes on Distributions and Sale of Fund Shares
Past 1 yearrr_AverageAnnualReturnYear012.44%
Past 5 yearsrr_AverageAnnualReturnYear052.05%
Life of classrr_AverageAnnualReturnSinceInception2.42%[4]
Inception Daterr_AverageAnnualReturnInceptionDateAug. 27, 2002
A T B C | Fidelity Investment Grade Bond Fund | Barclays Capital® U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital® U.S. Aggregate Bond Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for fees, expenses, or taxes)
Past 1 yearrr_AverageAnnualReturnYear016.54%
Past 5 yearsrr_AverageAnnualReturnYear055.80%
Life of classrr_AverageAnnualReturnSinceInception5.23%[4]
Inception Daterr_AverageAnnualReturnInceptionDateAug. 27, 2002
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_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks to provide investment results that correspond to the aggregate price and interest performance of the debt securities in the Barclays Capital® U.S. Aggregate Bond Index.
Fee Tablefsst35315_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFee Table
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThe following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionShareholder fees (fees paid directly from your investment)
Annual class operating expensesrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionAnnual class operating expenses (expenses that you pay each year as a % of the value of your investment)
Expense Examplerr_ExpenseExampleAbstract 
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:

Portfolio Turnoverfsst35315_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 106% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate106.00%
Strategy [Heading]rr_StrategyHeadingPrincipal Investment Strategies
Strategy Narrative [Text Block]rr_StrategyNarrativeTextBlock
  • Normally investing at least 80% of the fund's assets in bonds included in the Barclays Capital® 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) 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_RiskHeadingPrincipal 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.
  • Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.
  • 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.

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 Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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.
Risk Lose Money [Text]rr_RiskLoseMoneyYou could lose money by investing in the fund.
Performancefsst35315_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPerformance
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_PerformanceInformationIllustratesVariabilityOfReturnsThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFuturePast performance (before and after taxes) is not an indication of future performance.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddresswww.fidelity.com
Annual Total Returnsrr_BarChartTableAbstract 
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 Return4.86%September 30, 2001
Lowest Quarter Return-2.56%June 30, 2004
Year-to-Date Return 6.61% September 30, 2011
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Performance Table Headingrr_PerformanceTableHeadingAverage Annual Returns
Performance Table Narrativerr_PerformanceTableNarrativeTextBlockAfter-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, 2010
Performance Table Uses Highest Federal Raterr_PerformanceTableUsesHighestFederalRateAfter-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 One Class of after Tax Shown [Text]rr_PerformanceTableOneClassOfAfterTaxShownAfter-tax returns for Investor Class are shown in the table below and after-tax returns for other classes will vary.
Performance Table Not Relevant to Tax Deferredrr_PerformanceTableNotRelevantToTaxDeferredThe after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement.
Inv Adv | Spartan U.S. Bond Index Fund | Spartan U.S. Bond Index Fund - Investor Class
 
Shareholder feesrr_ShareholderFeesAbstract 
Annual index fund fee (for fund balances under $10,000)rr_MaximumAccountFee10.00
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.05%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets none
Other expensesrr_OtherExpensesOverAssets0.17%
Total annual operating expensesrr_ExpensesOverAssets0.22%[8]
Expenses Restated to Reflect Current [Text]rr_ExpensesRestatedToReflectCurrentBased on historical expenses, adjusted to reflect current fees.
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear0123
3 yearsrr_ExpenseExampleYear0371
5 yearsrr_ExpenseExampleYear05124
10 yearsrr_ExpenseExampleYear10280
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20018.08%
2002rr_AnnualReturn200210.22%
2003rr_AnnualReturn20034.91%
2004rr_AnnualReturn20044.36%
2005rr_AnnualReturn20052.26%
2006rr_AnnualReturn20064.33%
2007rr_AnnualReturn20075.40%
2008rr_AnnualReturn20083.76%
2009rr_AnnualReturn20096.45%
2010rr_AnnualReturn20106.29%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn4.86%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateSep. 30, 2001
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(2.56%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateJun. 30, 2004
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn6.61%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Inv Adv | Spartan U.S. Bond Index Fund | Spartan U.S. Bond Index Fund - Fidelity Advantage Class
 
Shareholder feesrr_ShareholderFeesAbstract 
Annual index fund fee (for fund balances under $10,000)rr_MaximumAccountFee10.00
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.05%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets none
Other expensesrr_OtherExpensesOverAssets0.12%
Total annual operating expensesrr_ExpensesOverAssets0.17%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear0117
3 yearsrr_ExpenseExampleYear0355
5 yearsrr_ExpenseExampleYear0596
10 yearsrr_ExpenseExampleYear10217
Performancefsst35315_FundPastPerformanceAbstract 
Performance One Year or Less [Text]rr_PerformanceOneYearOrLessPerformance 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 | Spartan U.S. Bond Index Fund - Investor Class
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelInvestor Class - Return Before Taxes
Past 1 yearrr_AverageAnnualReturnYear016.29%
Past 5 yearsrr_AverageAnnualReturnYear055.24%
Past 10 yearsrr_AverageAnnualReturnYear105.58%
Inv Adv | Spartan U.S. Bond Index Fund | Return After Taxes on Distributions | Spartan U.S. Bond Index Fund - Investor Class
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelInvestor Class - Return After Taxes on Distributions
Past 1 yearrr_AverageAnnualReturnYear015.06%
Past 5 yearsrr_AverageAnnualReturnYear053.68%
Past 10 yearsrr_AverageAnnualReturnYear103.85%
Inv Adv | Spartan U.S. Bond Index Fund | Return After Taxes on Distributions and Sale of Fund Shares | Spartan U.S. Bond Index Fund - Investor Class
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelInvestor Class - Return After Taxes on Distributions and Sale of Fund Shares
Past 1 yearrr_AverageAnnualReturnYear014.22%
Past 5 yearsrr_AverageAnnualReturnYear053.57%
Past 10 yearsrr_AverageAnnualReturnYear103.76%
Inv Adv | Spartan U.S. Bond Index Fund | Barclays Capital® U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital U.S. Aggregate Bond Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for fees, expenses, or taxes)
Past 1 yearrr_AverageAnnualReturnYear016.54%
Past 5 yearsrr_AverageAnnualReturnYear055.80%
Past 10 yearsrr_AverageAnnualReturnYear105.84%
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_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks to provide investment results that correspond to the aggregate price and interest performance of the debt securities in the Barclays Capital® U.S. Aggregate Bond Index.
Fee Tablefsst35315_FundFeesAndExpensesAbstract 
Expense [Heading]rr_ExpenseHeadingFee Table
Expense Narrative [Text Block]rr_ExpenseNarrativeTextBlockThe following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder Fees Caption [Text]rr_ShareholderFeesCaptionShareholder fees (fees paid directly from your investment)
Annual class operating expensesrr_OperatingExpensesAbstract 
Operating Expenses Caption [Text]rr_OperatingExpensesCaptionAnnual class operating expenses (expenses that you pay each year as a % of the value of your investment)
Expense Examplerr_ExpenseExampleAbstract 
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:

Portfolio Turnoverfsst35315_PortfolioTurnoverAltAbstract 
Portfolio Turnover [Heading]rr_PortfolioTurnoverHeadingPortfolio Turnover
Portfolio Turnover [Text Block]rr_PortfolioTurnoverTextBlockThe 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 106% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate106.00%
Strategy [Heading]rr_StrategyHeadingPrincipal Investment Strategies
Strategy Narrative [Text Block]rr_StrategyNarrativeTextBlock
  • Normally investing at least 80% of the fund's assets in bonds included in the Barclays Capital® 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) 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_RiskHeadingPrincipal 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.
  • Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.
  • 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.

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 Not Insured Depository Institution [Text]rr_RiskNotInsuredDepositoryInstitutionAn 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.
Risk Lose Money [Text]rr_RiskLoseMoneyYou could lose money by investing in the fund.
Performancefsst35315_FundPastPerformanceAbstract 
Bar Chart and Performance Table [Heading]rr_BarChartAndPerformanceTableHeadingPerformance
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_PerformanceInformationIllustratesVariabilityOfReturnsThe 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 Past Does Not Indicate Future [Text]rr_PerformancePastDoesNotIndicateFuturePast performance is not an indication of future performance.
Performance Availability Website Address [Text]rr_PerformanceAvailabilityWebSiteAddresswww.401k.com and log in for updated return information
Annual Total Returnsrr_BarChartTableAbstract 
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 Return4.86%September 30, 2001
Lowest Quarter Return-2.56%June 30, 2004
Year-to-Date Return6.61%September 30, 2011
Bar Chart, Returns for Class Not Offered in Prospectus [Text]rr_BarChartReturnsForClassNotOfferedInProspectusThe 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.
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Performance Table Headingrr_PerformanceTableHeading

Average Annual Returns

For the periods ended
December 31, 2010
Inst Adv Inst | Spartan U.S. Bond Index Fund | Spartan U.S. Bond Index Fund - Institutional Class
 
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder fees (fees paid directly from your investment)rr_ShareholderFeeOther none
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.05%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets none
Other expensesrr_OtherExpensesOverAssets0.02%
Total annual operating expensesrr_ExpensesOverAssets0.07%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear017
3 yearsrr_ExpenseExampleYear0323
5 yearsrr_ExpenseExampleYear0540
10 yearsrr_ExpenseExampleYear1090
Performancefsst35315_FundPastPerformanceAbstract 
Performance One Year or Less [Text]rr_PerformanceOneYearOrLessPerformance 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 | Spartan U.S. Bond Index Fund - Investor Class
 
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20018.08%[11]
2002rr_AnnualReturn200210.22%[11]
2003rr_AnnualReturn20034.91%[11]
2004rr_AnnualReturn20044.36%[11]
2005rr_AnnualReturn20052.26%[11]
2006rr_AnnualReturn20064.33%[11]
2007rr_AnnualReturn20075.40%[11]
2008rr_AnnualReturn20083.76%[11]
2009rr_AnnualReturn20096.45%[11]
2010rr_AnnualReturn20106.29%[11]
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn4.86%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateSep. 30, 2001
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(2.56%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateJun. 30, 2004
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn6.61%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelSpartan® U.S. Bond Index Fund - Investor Class
Past 1 yearrr_AverageAnnualReturnYear016.29%[11]
Past 5 yearsrr_AverageAnnualReturnYear055.24%[11]
Past 10 yearsrr_AverageAnnualReturnYear105.58%[11]
Inst Adv Inst | Spartan U.S. Bond Index Fund | Spartan U.S. Bond Index Fund - Fidelity Advantage Institutional Class
 
Shareholder feesrr_ShareholderFeesAbstract 
Shareholder fees (fees paid directly from your investment)rr_ShareholderFeeOther none
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.05%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets none
Other expensesrr_OtherExpensesOverAssets none
Total annual operating expensesrr_ExpensesOverAssets0.05%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear015
3 yearsrr_ExpenseExampleYear0316
5 yearsrr_ExpenseExampleYear0528
10 yearsrr_ExpenseExampleYear10 64
Performancefsst35315_FundPastPerformanceAbstract 
Performance One Year or Less [Text]rr_PerformanceOneYearOrLessPerformance 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 Capital® U.S. Aggregate Bond Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital U.S. Aggregate Bond Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for fees, expenses, or taxes)
Past 1 yearrr_AverageAnnualReturnYear016.54%
Past 5 yearsrr_AverageAnnualReturnYear055.80%
Past 10 yearsrr_AverageAnnualReturnYear105.84%
[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]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, unless terminated or modified earlier with the approval of the Board of Trustees. FMR may not discontinue or modify this arrangement without the approval of the Board of Trustees.
[4]From August 27, 2002.
[5]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, unless terminated or modified earlier with the approval of the Board of Trustees. FMR may not discontinue or modify this arrangement without the approval of the Board of Trustees.
[6]From October 8, 2008.
[7]From June 26, 2009.
[8]Based on historical expenses, adjusted to reflect current fees.
[9]From September 24, 2009.
[10]Declines over 6 years from 5.00% to 0%.
[11]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.