110002 - Disclosure - S000001469 [Member] Investment Objectives and Goals link:presentationLink link:definitionLink link:calculationLink 110003 - Disclosure - S000001469 [Member] Fees and Expenses link:presentationLink link:definitionLink link:calculationLink 110004 - Disclosure - S000001469 [Member] Investment Strategy link:presentationLink link:definitionLink link:calculationLink 110005 - Disclosure - S000001469 [Member] Investment Risks link:presentationLink link:definitionLink link:calculationLink 110006 - Disclosure - S000001469 [Member] Performance Management link:presentationLink link:definitionLink link:calculationLink 120010 - Disclosure - S000001469 [Member] Shareholder Fees link:presentationLink link:definitionLink link:calculationLink 120020 - Disclosure - S000001469 [Member] Annual Fund Operating Expenses link:presentationLink link:definitionLink link:calculationLink 120030 - Disclosure - S000001469 [Member] Expense Example link:presentationLink link:definitionLink link:calculationLink 120040 - Disclosure - S000001469 [Member] Expense Example, No Redemption link:presentationLink link:definitionLink link:calculationLink 120045 - Disclosure - S000001469 [Member] Risks Data link:presentationLink link:definitionLink link:calculationLink 120050 - Disclosure - S000001469 [Member] Annual Total Returns link:presentationLink link:definitionLink link:calculationLink 120060 - Disclosure - S000001469 [Member] Average Annual Total Returns link:presentationLink link:definitionLink link:calculationLink 120070 - Disclosure - S000001469 [Member] Market Index Performance link:presentationLink link:definitionLink link:calculationLink 110000 - Disclosure - S000001469 [Member] N-1A Cover link:presentationLink link:definitionLink link:calculationLink 110001 - Disclosure - S000001469 [Member] N-1A Supplement link:presentationLink link:definitionLink link:calculationLink 210002 - Disclosure - S000046220 [Member] Investment Objectives and Goals link:presentationLink link:definitionLink link:calculationLink 210003 - Disclosure - S000046220 [Member] Fees and Expenses link:presentationLink link:definitionLink link:calculationLink 210004 - Disclosure - S000046220 [Member] Investment Strategy link:presentationLink link:definitionLink link:calculationLink 210005 - Disclosure - S000046220 [Member] Investment Risks link:presentationLink link:definitionLink link:calculationLink 210006 - Disclosure - S000046220 [Member] Performance Management link:presentationLink link:definitionLink link:calculationLink 220010 - Disclosure - S000046220 [Member] Shareholder Fees link:presentationLink link:definitionLink link:calculationLink 220020 - Disclosure - S000046220 [Member] Annual Fund Operating Expenses link:presentationLink link:definitionLink link:calculationLink 220030 - Disclosure - S000046220 [Member] Expense Example link:presentationLink link:definitionLink link:calculationLink 220040 - Disclosure - S000046220 [Member] Expense Example, No Redemption link:presentationLink link:definitionLink link:calculationLink 220045 - Disclosure - S000046220 [Member] Risks Data link:presentationLink link:definitionLink link:calculationLink 220050 - Disclosure - S000046220 [Member] Annual Total Returns link:presentationLink link:definitionLink link:calculationLink 220060 - Disclosure - S000046220 [Member] Average Annual Total Returns link:presentationLink link:definitionLink link:calculationLink 220070 - Disclosure - S000046220 [Member] Market Index Performance link:presentationLink link:definitionLink link:calculationLink 210000 - Disclosure - S000046220 [Member] N-1A Cover link:presentationLink link:definitionLink link:calculationLink 210001 - Disclosure - S000046220 [Member] N-1A Supplement link:presentationLink link:definitionLink link:calculationLink 310002 - Disclosure - S000001470 [Member] Investment Objectives and Goals link:presentationLink link:definitionLink link:calculationLink 310003 - Disclosure - S000001470 [Member] Fees and Expenses link:presentationLink link:definitionLink link:calculationLink 310004 - Disclosure - S000001470 [Member] Investment Strategy link:presentationLink link:definitionLink link:calculationLink 310005 - Disclosure - S000001470 [Member] Investment Risks link:presentationLink link:definitionLink link:calculationLink 310006 - Disclosure - S000001470 [Member] Performance Management link:presentationLink link:definitionLink link:calculationLink 320010 - Disclosure - S000001470 [Member] Shareholder Fees link:presentationLink link:definitionLink link:calculationLink 320020 - Disclosure - S000001470 [Member] Annual Fund Operating Expenses link:presentationLink link:definitionLink link:calculationLink 320030 - Disclosure - S000001470 [Member] Expense Example link:presentationLink link:definitionLink link:calculationLink 320040 - Disclosure - S000001470 [Member] Expense Example, No Redemption link:presentationLink link:definitionLink link:calculationLink 320045 - Disclosure - S000001470 [Member] Risks Data link:presentationLink link:definitionLink link:calculationLink 320050 - Disclosure - S000001470 [Member] Annual Total Returns link:presentationLink link:definitionLink link:calculationLink 320060 - Disclosure - S000001470 [Member] Average Annual Total Returns link:presentationLink link:definitionLink link:calculationLink 320070 - Disclosure - S000001470 [Member] Market Index Performance link:presentationLink link:definitionLink link:calculationLink 310000 - Disclosure - S000001470 [Member] N-1A Cover link:presentationLink link:definitionLink link:calculationLink 310001 - Disclosure - S000001470 [Member] N-1A Supplement link:presentationLink link:definitionLink link:calculationLink 410002 - Disclosure - S000011985 [Member] Investment Objectives and Goals link:presentationLink link:definitionLink link:calculationLink 410003 - Disclosure - S000011985 [Member] Fees and Expenses link:presentationLink link:definitionLink link:calculationLink 410004 - Disclosure - S000011985 [Member] Investment Strategy link:presentationLink link:definitionLink link:calculationLink 410005 - 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Disclosure - S000011985 [Member] Average Annual Total Returns link:presentationLink link:definitionLink link:calculationLink 420070 - Disclosure - S000011985 [Member] Market Index Performance link:presentationLink link:definitionLink link:calculationLink 410000 - Disclosure - S000011985 [Member] N-1A Cover link:presentationLink link:definitionLink link:calculationLink 410001 - Disclosure - S000011985 [Member] N-1A Supplement link:presentationLink link:definitionLink link:calculationLink 510002 - Disclosure - S000001471 [Member] Investment Objectives and Goals link:presentationLink link:definitionLink link:calculationLink 510003 - Disclosure - S000001471 [Member] Fees and Expenses link:presentationLink link:definitionLink link:calculationLink 510004 - Disclosure - S000001471 [Member] Investment Strategy link:presentationLink link:definitionLink link:calculationLink 510005 - Disclosure - S000001471 [Member] Investment Risks link:presentationLink link:definitionLink link:calculationLink 510006 - Disclosure - S000001471 [Member] Performance Management link:presentationLink link:definitionLink link:calculationLink 520010 - Disclosure - S000001471 [Member] Shareholder Fees link:presentationLink link:definitionLink link:calculationLink 520020 - Disclosure - S000001471 [Member] Annual Fund Operating Expenses link:presentationLink link:definitionLink link:calculationLink 520030 - Disclosure - S000001471 [Member] Expense Example link:presentationLink link:definitionLink link:calculationLink 520040 - Disclosure - S000001471 [Member] Expense Example, No Redemption link:presentationLink link:definitionLink link:calculationLink 520045 - Disclosure - S000001471 [Member] Risks Data link:presentationLink link:definitionLink link:calculationLink 520050 - Disclosure - S000001471 [Member] Annual Total Returns link:presentationLink link:definitionLink link:calculationLink 520060 - Disclosure - S000001471 [Member] Average Annual Total Returns link:presentationLink link:definitionLink link:calculationLink 520070 - Disclosure - S000001471 [Member] Market Index Performance link:presentationLink link:definitionLink link:calculationLink 510000 - Disclosure - S000001471 [Member] N-1A Cover link:presentationLink link:definitionLink link:calculationLink 510001 - Disclosure - S000001471 [Member] N-1A Supplement link:presentationLink link:definitionLink link:calculationLink 610002 - Disclosure - S000071703 [Member] Investment Objectives and Goals link:presentationLink link:definitionLink link:calculationLink 610003 - Disclosure - S000071703 [Member] Fees and Expenses link:presentationLink link:definitionLink link:calculationLink 610004 - Disclosure - S000071703 [Member] Investment Strategy link:presentationLink link:definitionLink link:calculationLink 610005 - Disclosure - S000071703 [Member] Investment Risks link:presentationLink link:definitionLink link:calculationLink 610006 - Disclosure - S000071703 [Member] Performance Management link:presentationLink link:definitionLink link:calculationLink 620010 - 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Disclosure - S000071703 [Member] N-1A Cover link:presentationLink link:definitionLink link:calculationLink 610001 - Disclosure - S000071703 [Member] N-1A Supplement link:presentationLink link:definitionLink link:calculationLink 710002 - Disclosure - S000047014 [Member] Investment Objectives and Goals link:presentationLink link:definitionLink link:calculationLink 710003 - Disclosure - S000047014 [Member] Fees and Expenses link:presentationLink link:definitionLink link:calculationLink 710004 - Disclosure - S000047014 [Member] Investment Strategy link:presentationLink link:definitionLink link:calculationLink 710005 - Disclosure - S000047014 [Member] Investment Risks link:presentationLink link:definitionLink link:calculationLink 710006 - Disclosure - S000047014 [Member] Performance Management link:presentationLink link:definitionLink link:calculationLink 720010 - Disclosure - S000047014 [Member] Shareholder Fees link:presentationLink link:definitionLink link:calculationLink 720020 - Disclosure - S000047014 [Member] Annual Fund Operating Expenses link:presentationLink link:definitionLink link:calculationLink 720030 - Disclosure - S000047014 [Member] Expense Example link:presentationLink link:definitionLink link:calculationLink 720040 - Disclosure - S000047014 [Member] Expense Example, No Redemption link:presentationLink link:definitionLink link:calculationLink 720045 - Disclosure - S000047014 [Member] Risks Data link:presentationLink link:definitionLink link:calculationLink 720050 - Disclosure - S000047014 [Member] Annual Total Returns link:presentationLink link:definitionLink link:calculationLink 720060 - Disclosure - S000047014 [Member] Average Annual Total Returns link:presentationLink link:definitionLink link:calculationLink 720070 - Disclosure - S000047014 [Member] Market Index Performance link:presentationLink link:definitionLink link:calculationLink 710000 - Disclosure - S000047014 [Member] N-1A Cover link:presentationLink link:definitionLink link:calculationLink 710001 - Disclosure - S000047014 [Member] N-1A Supplement link:presentationLink link:definitionLink link:calculationLink BATS: Corporate Credit Total Return Series S000001469 [Member] Bloomberg U.S. Aggregate Bond Index (Reflects no deduction for fees, expenses or taxes) S000001469 Bloomberg US Aggregate Bond Index [Member] Bloomberg U.S. Credit Index (Reflects no deduction for fees, expenses or taxes) S000001469 Bloomberg US Credit Index [Member] C000003891 [Member] US Government Issuer Risk [Member] Foreign Securities Risk [Member] Derivatives Risks [Member] Industrials Sector Risk [Member] Illiquid Investments Risk [Member] Leverage Risk [Member] Market Risk and Selection Risk [Member] Mortgage and Asset Backed Securities Risks [Member] Operational and Technology Risks [Member] Repurchase Agreements and Purchase and Sale Contracts Risk [Member] Restricted Securities Risk [Member] Reverse Repurchase Agreements Risk [Member] Sovereign Debt Risk [Member] Supranational Entities Risk [Member] When Issued and Delayed Delivery Securities and Forward Commitments Risk [Member] Debt Securities Risk [Member] BATS: High Income Municipal Series S000046220 [Member] Bloomberg Municipal Bond Index (Reflects no deduction for fees, expenses or taxes) S000046220 Bloomberg Municipal Bond Index [Member] Bloomberg Municipal High Yield Bond Index S000046220 Bloomberg Municipal High Yield Bond Index [Member] Customized Reference Benchmark S000046220 Customized Reference Benchmark [Member] C000144517 [Member] Municipal Securities Risks [Member] High Yield Bonds Risk [Member] Distressed Securities Risk [Member] School District Investment Risk [Member] Risk of Investing in the United States [Member] Variable Rate Demand Obligations Risks [Member] Zero Coupon Securities Risk [Member] BATS: Mortgage Total Return Series S000001470 [Member] S000001470 Bloomberg US Aggregate Bond Index [Member] Bloomberg MBS Index (Reflects no deduction for fees, expenses or taxes) S000001470 Bloomberg MBS Index [Member] C000003892 [Member] Dollar Rolls Risk [Member] High Portfolio Turnover Risk [Member] BATS: Interest Rate Hedge Series S000011985 [Member] S000011985 Bloomberg U.S. Aggregate Bond Index [Member] Bloomberg U.S. Treasury 7-10 Year Bond Index (Reflects no deduction for fees, expenses or taxes) S000011985 Bloomberg US Treasury 7 10 Year Bond Index [Member] Bloomberg U.S. Bellwether 10 Year Swap Index (Reflects no deduction for fees, expenses or taxes) S000011985 Bloomberg US Bellwether 10 Year Swap Index [Member] C000032703 [Member] Short Sales Risk [Member] Investment in Other Investment Companies Risk [Member] BATS: Short Duration Taxable Total Return Series S000001471 [Member] S000001471 Bloomberg US Aggregate Bond Index [Member] ICE BofA 1-3 Year U.S. Treasury Index (Reflects no deduction for fees, expenses or taxes) S000001471 ICE BofA 1 3 Year US Treasury Index [Member] C000003893 [Member] Treasury Obligations Risk [Member] BATS: Short Term Municipal Income Series S000071703 [Member] S000071703 Bloomberg Municipal Bond Index [Member] SIFMA Municipal Swap Index (Reflects no deduction for fees, expenses or taxes) SIFMA Municipal Swap Index [Member] C000227189 [Member] Credit Risks [Member] Foreign Exposure Risk [Member] Income Risk [Member] Interest Rate Risks [Member] Taxability Risk [Member] U S Government Obligations Risk [Member] Variable and Floating Rate Instrument Risk [Member] BATS: Securitized Total Return Series S000047014 [Member] Bloomberg U.S. Universal Index (Reflects no deduction for fees, expenses or taxes Bloomberg U S Universal Index [Member] Reference Benchmark (Reflects no deduction for fees, expenses or taxes) Reference Benchmark [Member] C000146955 [Member] Loans Risk [Member] Collateralized Debt Obligations Risk [Member] Concentration Risk [Member] Indexed and Inverse Securities Risk [Member] Non Agency Securities Risk [Member]