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Risk/Return:rr_RiskReturnAbstract 
Document Typedei_DocumentType485BPOS
Document Period End Datedei_DocumentPeriodEndDateAug. 31, 2011
Registrant Namedei_EntityRegistrantNameFIDELITY ADVISOR SERIES II
Central Index Keydei_EntityCentralIndexKey0000795422
Amendment Flagdei_AmendmentFlagfalse
Document Creation Datedei_DocumentCreationDateOct. 27, 2011
Document Effective Datedei_DocumentEffectiveDateOct. 29, 2011
Prospectus Daterr_ProspectusDateOct. 29, 2011
A T B C | Fidelity Advisor Intermediate Bond Fund
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeading
Fund Summary
Fund/Class:
Fidelity Advisor® Intermediate Bond Fund/A, T, B, C
Objective [Heading]rr_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks to provide a high rate of income.
Fee Tablefas795422_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_ExpenseBreakpointMinimumInvestmentRequiredAmount 50,000
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 Turnoverfas795422_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 108% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate108.00%
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.
Performancefas795422_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 Return6.93%June 30, 2009
Lowest Quarter Return-3.66%December 31, 2008
Year-to-Date Return4.95%September 30, 2011
Average Annual Total 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.
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.
A T B C | Fidelity Advisor Intermediate Bond Fund | Fidelity Advisor Intermediate Bond Fund - Class A
 
Shareholder feesrr_ShareholderFeesAbstract 
Maximum sales charge (load) on purchases (as a % of offering price)rr_MaximumCumulativeSalesChargeOverOfferingPrice2.75%
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_ExpensesDeferredChargesTextBlockPurchases of $250,000 or more will not be subject to a front-end sales charge, but may be subject to a 0.50% contingent deferred sales charge (CDSC) if the intermediary has elected an upfront finder's fee at the time the shares are purchased, or a 0.75% CDSC if the shares purchased are recordkept in a Fidelity Advisor 401(k) Retirement Plan.
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.32%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other expensesrr_OtherExpensesOverAssets0.26%
Total annual operating expensesrr_ExpensesOverAssets0.83%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01357
3 yearsrr_ExpenseExampleYear03533
5 yearsrr_ExpenseExampleYear05723
10 yearsrr_ExpenseExampleYear101,272
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01357
3 yearsrr_ExpenseExampleNoRedemptionYear03533
5 yearsrr_ExpenseExampleNoRedemptionYear05723
10 yearsrr_ExpenseExampleNoRedemptionYear101,272
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20017.92%
2002rr_AnnualReturn200210.06%
2003rr_AnnualReturn20034.63%
2004rr_AnnualReturn20043.43%
2005rr_AnnualReturn20051.51%
2006rr_AnnualReturn20064.05%
2007rr_AnnualReturn20073.18%
2008rr_AnnualReturn2008(7.31%)
2009rr_AnnualReturn200917.26%
2010rr_AnnualReturn20107.73%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn6.93%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(3.66%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn4.95%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
A T B C | Fidelity Advisor Intermediate Bond Fund | Fidelity Advisor Intermediate Bond Fund - Class T
 
Shareholder feesrr_ShareholderFeesAbstract 
Maximum sales charge (load) on purchases (as a % of offering price)rr_MaximumCumulativeSalesChargeOverOfferingPrice2.75%
Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none [2]
Expenses Deferred Charges [Text Block]rr_ExpensesDeferredChargesTextBlockPurchases of $250,000 or more will not be subject to a front-end sales charge but may be subject to a 0.25% CDSC if a finder's fee is paid at the time the shares are purchased.
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.32%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets0.25%
Other expensesrr_OtherExpensesOverAssets0.23%
Total annual operating expensesrr_ExpensesOverAssets0.80%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01354
3 yearsrr_ExpenseExampleYear03523
5 yearsrr_ExpenseExampleYear05707
10 yearsrr_ExpenseExampleYear101,238
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01354
3 yearsrr_ExpenseExampleNoRedemptionYear03523
5 yearsrr_ExpenseExampleNoRedemptionYear05707
10 yearsrr_ExpenseExampleNoRedemptionYear101,238
A T B C | Fidelity Advisor Intermediate Bond Fund | Fidelity Advisor Intermediate 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_MaximumDeferredSalesChargeOverOther3.00%[3]
Expenses Deferred Charges [Text Block]rr_ExpensesDeferredChargesTextBlockDeclines over 3 years from 3.00% to 0%.
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.32%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets0.90%
Other expensesrr_OtherExpensesOverAssets0.33%
Total annual operating expensesrr_ExpensesOverAssets1.55%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01458
3 yearsrr_ExpenseExampleYear03590
5 yearsrr_ExpenseExampleYear05761
10 yearsrr_ExpenseExampleYear101,311
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01158
3 yearsrr_ExpenseExampleNoRedemptionYear03490
5 yearsrr_ExpenseExampleNoRedemptionYear05761
10 yearsrr_ExpenseExampleNoRedemptionYear101,311
A T B C | Fidelity Advisor Intermediate Bond Fund | Fidelity Advisor Intermediate 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%[4]
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_OtherExpensesOverAssets0.24%
Total annual operating expensesrr_ExpensesOverAssets1.56%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01259
3 yearsrr_ExpenseExampleYear03493
5 yearsrr_ExpenseExampleYear05850
10 yearsrr_ExpenseExampleYear101,856
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01159
3 yearsrr_ExpenseExampleNoRedemptionYear03493
5 yearsrr_ExpenseExampleNoRedemptionYear05850
10 yearsrr_ExpenseExampleNoRedemptionYear101,856
A T B C | Fidelity Advisor Intermediate Bond Fund | Return Before Taxes | Fidelity Advisor Intermediate Bond Fund - Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass A - Return Before Taxes
Past 1 yearrr_AverageAnnualReturnYear014.77%
Past 5 yearsrr_AverageAnnualReturnYear054.10%
Past 10 yearsrr_AverageAnnualReturnYear104.78%
A T B C | Fidelity Advisor Intermediate Bond Fund | Return Before Taxes | Fidelity Advisor Intermediate Bond Fund - Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass T - Return Before Taxes
Past 1 yearrr_AverageAnnualReturnYear014.70%
Past 5 yearsrr_AverageAnnualReturnYear054.08%
Past 10 yearsrr_AverageAnnualReturnYear104.72%
A T B C | Fidelity Advisor Intermediate Bond Fund | Return Before Taxes | Fidelity Advisor Intermediate Bond Fund - Class B
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass B - Return Before Taxes
Past 1 yearrr_AverageAnnualReturnYear013.88%
Past 5 yearsrr_AverageAnnualReturnYear054.09%
Past 10 yearsrr_AverageAnnualReturnYear104.74%
A T B C | Fidelity Advisor Intermediate Bond Fund | Return Before Taxes | Fidelity Advisor Intermediate Bond Fund - Class C
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass C - Return Before Taxes
Past 1 yearrr_AverageAnnualReturnYear015.88%
Past 5 yearsrr_AverageAnnualReturnYear053.88%
Past 10 yearsrr_AverageAnnualReturnYear104.22%
A T B C | Fidelity Advisor Intermediate Bond Fund | Return After Taxes on Distributions | Fidelity Advisor Intermediate Bond Fund - Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass A - Return After Taxes on Distributions
Past 1 yearrr_AverageAnnualReturnYear013.60%
Past 5 yearsrr_AverageAnnualReturnYear052.62%
Past 10 yearsrr_AverageAnnualReturnYear103.18%
A T B C | Fidelity Advisor Intermediate Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Fidelity Advisor Intermediate Bond Fund - Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass A - Return After Taxes on Distributions and Sale of Fund Shares
Past 1 yearrr_AverageAnnualReturnYear013.09%
Past 5 yearsrr_AverageAnnualReturnYear052.61%
Past 10 yearsrr_AverageAnnualReturnYear103.14%
A T B C | Fidelity Advisor Intermediate Bond Fund | Barclays Capital® U.S. Intermediate Government/Credit Bond Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Total 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%
A T B C | Fidelity Advisor Mortgage Securities Fund
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeading
Fund Summary
Fund/Class:
Fidelity Advisor® Mortgage Securities Fund/A, T, B, C
Objective [Heading]rr_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks a high level of current income, consistent with prudent investment risk. In seeking current income, the fund may also consider the potential for capital gain.
Fee Tablefas795422_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 Turnoverfas795422_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 490% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate490.00%
Strategy [Heading]rr_StrategyHeadingPrincipal Investment Strategies
Strategy Narrative [Text Block]rr_StrategyNarrativeTextBlock
  • Normally investing at least 80% of assets in investment-grade mortgage-related securities (those of medium and high quality) and repurchase agreements for those securities.
  • Investing in U.S. Government securities and instruments related to U.S. Government securities.
  • Investing in U.S. Government securities issued by entities that are chartered or sponsored by Congress but whose securities are neither issued nor guaranteed by the U.S. Treasury.
  • Managing the fund to have similar overall interest rate risk to the Barclays Capital® U.S. MBS Index.
  • Allocating assets across different market sectors and maturities.
  • 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.
  • 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.
Performancefas795422_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 Return3.98%September 30, 2001
Lowest Quarter Return-1.56%June 30, 2007
Year-to-Date Return5.21%September 30, 2011
Average Annual Total 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 Advisor Mortgage Securities Fund | Fidelity Advisor Mortgage Securities 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 [5]
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_OtherExpensesOverAssets0.25%
Total annual operating expensesrr_ExpensesOverAssets0.82%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01480
3 yearsrr_ExpenseExampleYear03651
5 yearsrr_ExpenseExampleYear05837
10 yearsrr_ExpenseExampleYear101,373
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01480
3 yearsrr_ExpenseExampleNoRedemptionYear03651
5 yearsrr_ExpenseExampleNoRedemptionYear05837
10 yearsrr_ExpenseExampleNoRedemptionYear101,373
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20017.37%
2002rr_AnnualReturn20028.81%
2003rr_AnnualReturn20033.34%
2004rr_AnnualReturn20044.21%
2005rr_AnnualReturn20052.21%
2006rr_AnnualReturn20064.55%
2007rr_AnnualReturn2007(0.76%)
2008rr_AnnualReturn20080.90%
2009rr_AnnualReturn20099.17%
2010rr_AnnualReturn20106.88%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn3.98%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2001
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(1.56%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateJun. 30, 2007
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn5.21%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
A T B C | Fidelity Advisor Mortgage Securities Fund | Fidelity Advisor Mortgage Securities 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 [5]
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_OtherExpensesOverAssets0.22%
Total annual operating expensesrr_ExpensesOverAssets0.79%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01477
3 yearsrr_ExpenseExampleYear03642
5 yearsrr_ExpenseExampleYear05821
10 yearsrr_ExpenseExampleYear101,339
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01477
3 yearsrr_ExpenseExampleNoRedemptionYear03642
5 yearsrr_ExpenseExampleNoRedemptionYear05821
10 yearsrr_ExpenseExampleNoRedemptionYear101,339
A T B C | Fidelity Advisor Mortgage Securities Fund | Fidelity Advisor Mortgage Securities 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%[6]
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_OtherExpensesOverAssets0.28%
Total annual operating expensesrr_ExpensesOverAssets1.50%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01653
3 yearsrr_ExpenseExampleYear03774
5 yearsrr_ExpenseExampleYear051,018
10 yearsrr_ExpenseExampleYear101,520
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01153
3 yearsrr_ExpenseExampleNoRedemptionYear03474
5 yearsrr_ExpenseExampleNoRedemptionYear05818
10 yearsrr_ExpenseExampleNoRedemptionYear101,520
A T B C | Fidelity Advisor Mortgage Securities Fund | Fidelity Advisor Mortgage Securities 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%[4]
Expenses Deferred Charges [Text Block]rr_ExpensesDeferredChargesTextBlock On 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 Advisor Mortgage Securities Fund | Return Before Taxes | Fidelity Advisor Mortgage Securities Fund - Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass A - Return Before Taxes
Past 1 yearrr_AverageAnnualReturnYear012.60%
Past 5 yearsrr_AverageAnnualReturnYear053.23%
Past 10 yearsrr_AverageAnnualReturnYear104.19%
A T B C | Fidelity Advisor Mortgage Securities Fund | Return Before Taxes | Fidelity Advisor Mortgage Securities Fund - Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass T - Return Before Taxes
Past 1 yearrr_AverageAnnualReturnYear012.71%
Past 5 yearsrr_AverageAnnualReturnYear053.22%
Past 10 yearsrr_AverageAnnualReturnYear104.14%
A T B C | Fidelity Advisor Mortgage Securities Fund | Return Before Taxes | Fidelity Advisor Mortgage Securities Fund - Class B
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass B - Return Before Taxes
Past 1 yearrr_AverageAnnualReturnYear011.26%
Past 5 yearsrr_AverageAnnualReturnYear053.03%
Past 10 yearsrr_AverageAnnualReturnYear104.07%
A T B C | Fidelity Advisor Mortgage Securities Fund | Return Before Taxes | Fidelity Advisor Mortgage Securities Fund - Class C
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass C - Return Before Taxes
Past 1 yearrr_AverageAnnualReturnYear015.24%
Past 5 yearsrr_AverageAnnualReturnYear053.31%
Life of classrr_AverageAnnualReturnSinceInception3.57%[7]
Inception Daterr_AverageAnnualReturnInceptionDateAug. 16, 2001
A T B C | Fidelity Advisor Mortgage Securities Fund | Return After Taxes on Distributions | Fidelity Advisor Mortgage Securities Fund - Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass A - Return After Taxes on Distributions
Past 1 yearrr_AverageAnnualReturnYear011.44%
Past 5 yearsrr_AverageAnnualReturnYear051.65%
Past 10 yearsrr_AverageAnnualReturnYear102.55%
A T B C | Fidelity Advisor Mortgage Securities Fund | Return After Taxes on Distributions and Sale of Fund Shares | Fidelity Advisor Mortgage Securities Fund - Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass A - Return After Taxes on Distributions and Sale of Fund Shares
Past 1 yearrr_AverageAnnualReturnYear011.68%
Past 5 yearsrr_AverageAnnualReturnYear051.81%
Past 10 yearsrr_AverageAnnualReturnYear102.59%
A T B C | Fidelity Advisor Mortgage Securities Fund | Barclays Capital® U.S. MBS Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital® U.S. MBS Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for fees , expenses, or taxes)
Past 1 yearrr_AverageAnnualReturnYear015.37%
Past 5 yearsrr_AverageAnnualReturnYear056.34%
Past 10 yearsrr_AverageAnnualReturnYear105.89%
A T B C | Fidelity Advisor Short Fixed-Income Fund
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeading
Fund Summary
Fund/Class:
Fidelity Advisor® Short Fixed-Income Fund/A, T, B, C
Objective [Heading]rr_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks to obtain a high level of current income consistent with the preservation of capital.
Fee Tablefas795422_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 $250,000 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 $250,000 in the fund or certain other Fidelity funds.
Expense Breakpoint, Minimum Investment Required [Amount]rr_ExpenseBreakpointMinimumInvestmentRequiredAmount250,000
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 Turnoverfas795422_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 204% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate204.00%
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.
Performancefas795422_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 Return3.00%September 30, 2001
Lowest Quarter Return-1.37%December 31, 2008
Year-to-Date Return1.56%September 30, 2011
Average Annual Total 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 Advisor Short Fixed-Income Fund | Fidelity Advisor Short Fixed-Income Fund - Class A
 
Shareholder feesrr_ShareholderFeesAbstract 
Maximum sales charge (load) on purchases (as a % of offering price)rr_MaximumCumulativeSalesChargeOverOfferingPrice1.50%
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_ExpensesDeferredChargesTextBlockPurchases of $250,000 or more will not be subject to a front-end sales charge, but may be subject to a 0.50% contingent deferred sales charge (CDSC) if the intermediary has elected an upfront finder's fee at the time the shares are purchased, or a 0.75% CDSC if the shares purchased are recordkept in a Fidelity Advisor 401(k) Retirement Plan.
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.32%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets0.15%
Other expensesrr_OtherExpensesOverAssets0.23%
Total annual operating expensesrr_ExpensesOverAssets0.70%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01220
3 yearsrr_ExpenseExampleYear03371
5 yearsrr_ExpenseExampleYear05534
10 yearsrr_ExpenseExampleYear101,007
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01220
3 yearsrr_ExpenseExampleNoRedemptionYear03371
5 yearsrr_ExpenseExampleNoRedemptionYear05534
10 yearsrr_ExpenseExampleNoRedemptionYear101,007
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20016.89%
2002rr_AnnualReturn20026.29%
2003rr_AnnualReturn20033.27%
2004rr_AnnualReturn20041.62%
2005rr_AnnualReturn20051.73%
2006rr_AnnualReturn20064.33%
2007rr_AnnualReturn20072.49%
2008rr_AnnualReturn2008(2.73%)
2009rr_AnnualReturn20096.74%
2010rr_AnnualReturn20103.54%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn3.00%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateSep. 30, 2001
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(1.37%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn1.56%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
A T B C | Fidelity Advisor Short Fixed-Income Fund | Fidelity Advisor Short Fixed-Income Fund - Class T
 
Shareholder feesrr_ShareholderFeesAbstract 
Maximum sales charge (load) on purchases (as a % of offering price)rr_MaximumCumulativeSalesChargeOverOfferingPrice1.50%
Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)rr_MaximumDeferredSalesChargeOverOther none [2]
Expenses Deferred Charges [Text Block]rr_ExpensesDeferredChargesTextBlockPurchases of $250,000 or more will not be subject to a front-end sales charge but may be subject to a 0.25% CDSC if a finder's fee is paid at the time the shares are purchased.
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.32%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets0.15%
Other expensesrr_OtherExpensesOverAssets0.23%
Total annual operating expensesrr_ExpensesOverAssets0.70%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01220
3 yearsrr_ExpenseExampleYear03371
5 yearsrr_ExpenseExampleYear05534
10 yearsrr_ExpenseExampleYear101,007
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01220
3 yearsrr_ExpenseExampleNoRedemptionYear03371
5 yearsrr_ExpenseExampleNoRedemptionYear05534
10 yearsrr_ExpenseExampleNoRedemptionYear101,007
A T B C | Fidelity Advisor Short Fixed-Income Fund | Fidelity Advisor Short Fixed-Income 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_MaximumDeferredSalesChargeOverOther3.00%[3]
Expenses Deferred Charges [Text Block]rr_ExpensesDeferredChargesTextBlockDeclines over 3 years from 3.00% to 0%.
Annual class operating expensesrr_OperatingExpensesAbstract 
Management feerr_ManagementFeesOverAssets0.32%
Distribution and/or Service (12b-1) feesrr_DistributionAndService12b1FeesOverAssets0.90%
Other expensesrr_OtherExpensesOverAssets0.30%
Total annual operating expensesrr_ExpensesOverAssets1.52%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01455
3 yearsrr_ExpenseExampleYear03580
5 yearsrr_ExpenseExampleYear05734
10 yearsrr_ExpenseExampleYear101,200
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01155
3 yearsrr_ExpenseExampleNoRedemptionYear03480
5 yearsrr_ExpenseExampleNoRedemptionYear05734
10 yearsrr_ExpenseExampleNoRedemptionYear101,200
A T B C | Fidelity Advisor Short Fixed-Income Fund | Fidelity Advisor Short Fixed-Income 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%[4]
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_OtherExpensesOverAssets0.22%
Total annual operating expensesrr_ExpensesOverAssets1.54%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear01257
3 yearsrr_ExpenseExampleYear03486
5 yearsrr_ExpenseExampleYear05839
10 yearsrr_ExpenseExampleYear101,834
Expense Example, No Redemptionrr_ExpenseExampleNoRedemptionAbstract 
1 yearrr_ExpenseExampleNoRedemptionYear01157
3 yearsrr_ExpenseExampleNoRedemptionYear03486
5 yearsrr_ExpenseExampleNoRedemptionYear05839
10 yearsrr_ExpenseExampleNoRedemptionYear101,834
A T B C | Fidelity Advisor Short Fixed-Income Fund | Return Before Taxes | Fidelity Advisor Short Fixed-Income Fund - Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass A - Return Before Taxes
Past 1 yearrr_AverageAnnualReturnYear011.99%
Past 5 yearsrr_AverageAnnualReturnYear052.51%
Past 10 yearsrr_AverageAnnualReturnYear103.22%
A T B C | Fidelity Advisor Short Fixed-Income Fund | Return Before Taxes | Fidelity Advisor Short Fixed-Income Fund - Class T
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass T - Return Before Taxes
Past 1 yearrr_AverageAnnualReturnYear011.99%
Past 5 yearsrr_AverageAnnualReturnYear052.55%
Past 10 yearsrr_AverageAnnualReturnYear103.24%
A T B C | Fidelity Advisor Short Fixed-Income Fund | Return Before Taxes | Fidelity Advisor Short Fixed-Income Fund - Class B
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass B - Return Before Taxes
Past 1 yearrr_AverageAnnualReturnYear01(0.18%)
Past 5 yearsrr_AverageAnnualReturnYear052.19%
Life of classrr_AverageAnnualReturnSinceInception2.39%[8]
Inception Daterr_AverageAnnualReturnInceptionDateOct. 09, 2002
A T B C | Fidelity Advisor Short Fixed-Income Fund | Return Before Taxes | Fidelity Advisor Short Fixed-Income Fund - Class C
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass C - Return Before Taxes
Past 1 yearrr_AverageAnnualReturnYear011.68%
Past 5 yearsrr_AverageAnnualReturnYear051.99%
Past 10 yearsrr_AverageAnnualReturnYear102.55%
A T B C | Fidelity Advisor Short Fixed-Income Fund | Return After Taxes on Distributions | Fidelity Advisor Short Fixed-Income Fund - Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass A - Return After Taxes on Distributions
Past 1 yearrr_AverageAnnualReturnYear011.34%
Past 5 yearsrr_AverageAnnualReturnYear051.38%
Past 10 yearsrr_AverageAnnualReturnYear101.98%
A T B C | Fidelity Advisor Short Fixed-Income Fund | Return After Taxes on Distributions and Sale of Fund Shares | Fidelity Advisor Short Fixed-Income Fund - Class A
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelClass A - Return After Taxes on Distributions and Sale of Fund Shares
Past 1 yearrr_AverageAnnualReturnYear011.29%
Past 5 yearsrr_AverageAnnualReturnYear051.47%
Past 10 yearsrr_AverageAnnualReturnYear102.01%
A T B C | Fidelity Advisor Short Fixed-Income Fund | Barclays Capital® U.S. 1-3 Year Government/Credit Bond Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Total 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%
Inst | Fidelity Advisor Intermediate Bond Fund
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeading
Fund Summary
Fund/Class:
Fidelity Advisor® Intermediate Bond Fund/Institutional
Objective [Heading]rr_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks to provide a high rate of income.
Fee Tablefas795422_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 Turnoverfas795422_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 108% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate108.00%
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.
Performancefas795422_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 Return7.02%June 30, 2009
Lowest Quarter Return-3.57%December 31, 2008
Year-to-Date Return5.23%September 30, 2011
Average Annual Total 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.
Inst | Fidelity Advisor Intermediate Bond Fund | Fidelity Advisor Intermediate 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_OtherExpensesOverAssets0.26%
Total annual operating expensesrr_ExpensesOverAssets0.58%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear0159
3 yearsrr_ExpenseExampleYear03186
5 yearsrr_ExpenseExampleYear05324
10 yearsrr_ExpenseExampleYear10726
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20018.08%
2002rr_AnnualReturn200210.31%
2003rr_AnnualReturn20034.77%
2004rr_AnnualReturn20043.58%
2005rr_AnnualReturn20051.68%
2006rr_AnnualReturn20064.22%
2007rr_AnnualReturn20073.44%
2008rr_AnnualReturn2008(6.98%)
2009rr_AnnualReturn200917.71%
2010rr_AnnualReturn20107.90%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn7.02%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateJun. 30, 2009
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(3.57%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn5.23%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Inst | Fidelity Advisor Intermediate Bond Fund | Return Before Taxes | Fidelity Advisor Intermediate Bond Fund - Institutional Class
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameInstitutional Class
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
Past 1 yearrr_AverageAnnualReturnYear017.90%
Past 5 yearsrr_AverageAnnualReturnYear054.96%
Past 10 yearsrr_AverageAnnualReturnYear105.30%
Inst | Fidelity Advisor Intermediate Bond Fund | Return After Taxes on Distributions | Fidelity Advisor Intermediate Bond Fund - Institutional Class
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameInstitutional Class
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
Past 1 yearrr_AverageAnnualReturnYear016.60%
Past 5 yearsrr_AverageAnnualReturnYear053.37%
Past 10 yearsrr_AverageAnnualReturnYear103.62%
Inst | Fidelity Advisor Intermediate Bond Fund | Return After Taxes on Distributions and Sale of Fund Shares | Fidelity Advisor Intermediate Bond Fund - Institutional Class
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameInstitutional Class
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares
Past 1 yearrr_AverageAnnualReturnYear015.12%
Past 5 yearsrr_AverageAnnualReturnYear053.28%
Past 10 yearsrr_AverageAnnualReturnYear103.54%
Inst | Fidelity Advisor Intermediate Bond Fund | Barclays Capital® U.S. Intermediate Government/Credit Bond Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Total 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%
Inst | Fidelity Advisor Mortgage Securities Fund
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeading
Fund Summary
Fund/Class:
Fidelity Advisor® Mortgage Securities Fund/Institutional
Objective [Heading]rr_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks a high level of current income, consistent with prudent investment risk. In seeking current income, the fund may also consider the potential for capital gain.
Fee Tablefas795422_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 Turnoverfas795422_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 490% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate490.00%
Strategy [Heading]rr_StrategyHeadingPrincipal Investment Strategies
Strategy Narrative [Text Block]rr_StrategyNarrativeTextBlock
  • Normally investing at least 80% of assets in investment-grade mortgage-related securities (those of medium and high quality) and repurchase agreements for those securities.
  • Investing in U.S. Government securities and instruments related to U.S. Government securities.
  • Investing in U.S. Government securities issued by entities that are chartered or sponsored by Congress but whose securities are neither issued nor guaranteed by the U.S. Treasury.
  • Managing the fund to have similar overall interest rate risk to the Barclays Capital® U.S. MBS Index.
  • Allocating assets across different market sectors and maturities.
  • 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.
  • 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.
Performancefas795422_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 Return4.00%September 30, 2001
Lowest Quarter Return-1.49%June 30, 2007
Year-to-Date Return5.45%September 30, 2001
Average Annual Total 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 Advisor Mortgage Securities Fund | Fidelity Advisor Mortgage Securities 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_OtherExpensesOverAssets0.21%
Total annual operating expensesrr_ExpensesOverAssets0.53%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear0154
3 yearsrr_ExpenseExampleYear03170
5 yearsrr_ExpenseExampleYear05296
10 yearsrr_ExpenseExampleYear10665
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20017.48%
2002rr_AnnualReturn20028.92%
2003rr_AnnualReturn20033.54%
2004rr_AnnualReturn20044.43%
2005rr_AnnualReturn20052.44%
2006rr_AnnualReturn20064.77%
2007rr_AnnualReturn2007(0.48%)
2008rr_AnnualReturn20081.21%
2009rr_AnnualReturn20099.53%
2010rr_AnnualReturn20107.21%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn4.00%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateSep. 30, 2001
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(1.49%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateJun. 30, 2007
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn5.45%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2001
Inst | Fidelity Advisor Mortgage Securities Fund | Return Before Taxes | Fidelity Advisor Mortgage Securities Fund - Institutional Class
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameInstitutional Class
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
Past 1 yearrr_AverageAnnualReturnYear017.21%
Past 5 yearsrr_AverageAnnualReturnYear054.38%
Past 10 yearsrr_AverageAnnualReturnYear104.86%
Inst | Fidelity Advisor Mortgage Securities Fund | Return After Taxes on Distributions | Fidelity Advisor Mortgage Securities Fund - Institutional Class
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameInstitutional Class
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
Past 1 yearrr_AverageAnnualReturnYear015.88%
Past 5 yearsrr_AverageAnnualReturnYear052.68%
Past 10 yearsrr_AverageAnnualReturnYear103.12%
Inst | Fidelity Advisor Mortgage Securities Fund | Return After Taxes on Distributions and Sale of Fund Shares | Fidelity Advisor Mortgage Securities Fund - Institutional Class
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameInstitutional Class
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares
Past 1 yearrr_AverageAnnualReturnYear014.67%
Past 5 yearsrr_AverageAnnualReturnYear052.72%
Past 10 yearsrr_AverageAnnualReturnYear103.11%
Inst | Fidelity Advisor Mortgage Securities Fund | Barclays Capital® U.S. MBS Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital® U.S. MBS Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for fees, expenses, or taxes)
Past 1 yearrr_AverageAnnualReturnYear015.37%
Past 5 yearsrr_AverageAnnualReturnYear056.34%
Past 10 yearsrr_AverageAnnualReturnYear105.89%
Inst | Fidelity Advisor Short Fixed-Income Fund
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeading
Fund Summary
Fund/Class:
Fidelity Advisor® Short Fixed-Income 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 the preservation of capital.
Fee Tablefas795422_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 Turnoverfas795422_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 204% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate204.00%
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.
Performancefas795422_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 Return2.94%September 30, 2001
Lowest Quarter Return-1.42%December 31, 2008
Year-to-Date Return1.58%September 30, 2011
Average Annual Total 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 Advisor Short Fixed-Income Fund | Fidelity Advisor Short Fixed-Income 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_OtherExpensesOverAssets0.21%
Total annual operating expensesrr_ExpensesOverAssets0.53%
Expense Examplerr_ExpenseExampleAbstract 
1 yearrr_ExpenseExampleYear0154
3 yearsrr_ExpenseExampleYear03170
5 yearsrr_ExpenseExampleYear05296
10 yearsrr_ExpenseExampleYear10665
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20017.20%
2002rr_AnnualReturn20026.47%
2003rr_AnnualReturn20033.35%
2004rr_AnnualReturn20041.96%
2005rr_AnnualReturn20051.83%
2006rr_AnnualReturn20064.54%
2007rr_AnnualReturn20072.72%
2008rr_AnnualReturn2008(2.49%)
2009rr_AnnualReturn20097.04%
2010rr_AnnualReturn20103.72%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn2.94%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateSep. 30, 2001
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(1.42%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateDec. 31, 2008
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn1.58%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Inst | Fidelity Advisor Short Fixed-Income Fund | Return Before Taxes | Fidelity Advisor Short Fixed-Income Fund - Institutional Class
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameInstitutional Class
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
Past 1 yearrr_AverageAnnualReturnYear013.72%
Past 5 yearsrr_AverageAnnualReturnYear053.06%
Past 10 yearsrr_AverageAnnualReturnYear103.60%
Inst | Fidelity Advisor Short Fixed-Income Fund | Return After Taxes on Distributions | Fidelity Advisor Short Fixed-Income Fund - Institutional Class
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameInstitutional Class
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
Past 1 yearrr_AverageAnnualReturnYear012.99%
Past 5 yearsrr_AverageAnnualReturnYear051.84%
Past 10 yearsrr_AverageAnnualReturnYear102.28%
Inst | Fidelity Advisor Short Fixed-Income Fund | Return After Taxes on Distributions and Sale of Fund Shares | Fidelity Advisor Short Fixed-Income Fund - Institutional Class
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameInstitutional Class
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares
Past 1 yearrr_AverageAnnualReturnYear012.41%
Past 5 yearsrr_AverageAnnualReturnYear051.89%
Past 10 yearsrr_AverageAnnualReturnYear102.28%
Inst | Fidelity Advisor Short Fixed-Income Fund | Barclays Capital® U.S. 1-3 Year Government/Credit Bond Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Total 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%
Retail | Fidelity Advisor Mortgage Securities Fund
 
Risk/Return:rr_RiskReturnAbstract 
Risk/Return [Heading]rr_RiskReturnHeading
Fund Summary
Fund/Class:
Fidelity Advisor® Mortgage Securities Fund/Fidelity® Mortgage Securities Fund
Objective [Heading]rr_ObjectiveHeadingInvestment Objective
Objective, Primary [Text Block]rr_ObjectivePrimaryTextBlockThe fund seeks a high level of current income, consistent with prudent investment risk. In seeking current income, the fund may also consider the potential for capital gain.
Fee Tablefas795422_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 Turnoverfas795422_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 490% of the average value of its portfolio.
Portfolio Turnover, Raterr_PortfolioTurnoverRate490.00%
Strategy [Heading]rr_StrategyHeadingPrincipal Investment Strategies
Strategy Narrative [Text Block]rr_StrategyNarrativeTextBlock
  • Normally investing at least 80% of assets in investment-grade mortgage-related securities (those of medium and high quality) and repurchase agreements for those securities.
  • Investing in U.S. Government securities and instruments related to U.S. Government securities.
  • Investing in U.S. Government securities issued by entities that are chartered or sponsored by Congress but whose securities are neither issued nor guaranteed by the U.S. Treasury.
  • Managing the fund to have similar overall interest rate risk to the Barclays Capital® U.S. MBS Index.
  • Allocating assets across different market sectors and maturities.
  • 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.
  • 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.
Performancefas795422_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 Return4.02%September 30, 2001
Lowest Quarter Return-1.46%June 30, 2007
Year-to-Date Return5.58%September 30, 2011
Average Annual Total 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 Advisor Mortgage Securities Fund | Class: Fidelity Advisor Mortgage Securities 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_ExpenseExampleYear10 567
Annual Total Returnsrr_BarChartTableAbstract 
2001rr_AnnualReturn20017.56%
2002rr_AnnualReturn20029.12%
2003rr_AnnualReturn20033.55%
2004rr_AnnualReturn20044.45%
2005rr_AnnualReturn20052.48%
2006rr_AnnualReturn20064.84%
2007rr_AnnualReturn2007(0.39%)
2008rr_AnnualReturn20081.29%
2009rr_AnnualReturn20099.57%
2010rr_AnnualReturn20107.26%
Highest Quarterly Return, Labelrr_HighestQuarterlyReturnLabelHighest Quarter Return
Highest Quarterly Returnrr_BarChartHighestQuarterlyReturn4.02%
Highest Quarterly Return, Daterr_BarChartHighestQuarterlyReturnDateSep. 30, 2001
Lowest Quarterly Return, Labelrr_LowestQuarterlyReturnLabelLowest Quarter Return
Lowest Quarterly Returnrr_BarChartLowestQuarterlyReturn(1.46%)
Lowest Quarterly Return, Daterr_BarChartLowestQuarterlyReturnDateJun. 30, 2007
Year to Date Return, Labelrr_YearToDateReturnLabelYear-to-Date Return
Bar Chart, Year to Date Returnrr_BarChartYearToDateReturn5.58%
Bar Chart, Year to Date Return, Daterr_BarChartYearToDateReturnDateSep. 30, 2011
Retail | Fidelity Advisor Mortgage Securities Fund | Return Before Taxes | Class: Fidelity Advisor Mortgage Securities Fund
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameFidelity Mortgage Securities Fund
Labelrr_AverageAnnualReturnLabelReturn Before Taxes
Past 1 yearrr_AverageAnnualReturnYear017.26%
Past 5 yearsrr_AverageAnnualReturnYear054.45%
Past 10 yearsrr_AverageAnnualReturnYear104.92%
Retail | Fidelity Advisor Mortgage Securities Fund | Return After Taxes on Distributions | Class: Fidelity Advisor Mortgage Securities Fund
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameFidelity Mortgage Securities Fund
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions
Past 1 yearrr_AverageAnnualReturnYear015.91%
Past 5 yearsrr_AverageAnnualReturnYear052.72%
Past 10 yearsrr_AverageAnnualReturnYear103.17%
Retail | Fidelity Advisor Mortgage Securities Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class: Fidelity Advisor Mortgage Securities Fund
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Columnrr_AverageAnnualReturnColumnNameFidelity Mortgage Securities Fund
Labelrr_AverageAnnualReturnLabelReturn After Taxes on Distributions and Sale of Fund Shares
Past 1 yearrr_AverageAnnualReturnYear014.70%
Past 5 yearsrr_AverageAnnualReturnYear052.77%
Past 10 yearsrr_AverageAnnualReturnYear103.16%
Retail | Fidelity Advisor Mortgage Securities Fund | Barclays Capital® U.S. MBS Index (reflects no deduction for fees, expenses, or taxes)
 
Average Annual Total Returnsrr_AverageAnnualReturnAbstract 
Labelrr_AverageAnnualReturnLabelBarclays Capital® U.S. MBS Index
Index No Deduction for Fees, Expenses, Taxes [Text]rr_IndexNoDeductionForFeesExpensesTaxes(reflects no deduction for fees, expenses, or taxes)
Past 1 yearrr_AverageAnnualReturnYear015.37%
Past 5 yearsrr_AverageAnnualReturnYear056.34%
Past 10 yearsrr_AverageAnnualReturnYear105.89%
[1]Purchases of $250,000 or more will not be subject to a front-end sales charge, but may be subject to a 0.50% contingent deferred sales charge (CDSC) if the intermediary has elected an upfront finder's fee at the time the shares are purchased, or a 0.75% CDSC if the shares purchased are recordkept in a Fidelity Advisor 401(k) Retirement Plan.
[2]Purchases of $250,000 or more will not be subject to a front-end sales charge but may be subject to a 0.25% CDSC if a finder's fee is paid at the time the shares are purchased.
[3]Declines over 3 years from 3.00% to 0%.
[4]On Class C shares redeemed less than one year after purchase.
[5]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.
[6]Declines over 6 years from 5.00% to 0%.
[7]From August 16, 2001.
[8]From October 9, 2002.