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Investments in Mortgage Revenue Bonds Narrative Tagging (Details) (USD $)
3 Months Ended 6 Months Ended
Mar. 31, 2015
Integer
Mar. 31, 2014
Jun. 30, 2014
Dec. 31, 2014
Payments to Acquire Available-for-sale Securities $ 58,945,000us-gaap_PaymentsToAcquireAvailableForSaleSecurities $ 34,778,800us-gaap_PaymentsToAcquireAvailableForSaleSecurities    
Number of Available for Sale Securities 57atax_NumberOfAvailableForSaleSecurities      
Loans Payable 16,125,051us-gaap_LoansReceivableNet     15,990,439us-gaap_LoansReceivableNet
Available-for-sale Securities, Amortized Cost Basis, Held in Trust 386,280,003atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust     338,861,752atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
Cost adjusted for pay-downs 76,919,779us-gaap_AvailableForSaleSecuritiesAmortizedCost     65,538,068us-gaap_AvailableForSaleSecuritiesAmortizedCost
Available-For-Sale Securities, Gross Unrealized Loss MTM 17,516atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM     19,582atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
Mortgage revenue bonds held in trust, at fair value 426,022,847atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust     378,423,092atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
Proceeds from Sale of Available-for-sale Securities 0us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities 18,744,294us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities    
Available-for-sale Securities, Gross Realized Gain (Loss)   (1,743,088)us-gaap_AvailableForSaleSecuritiesGrossRealizedGainLossNet    
Debt financing 379,307,493atax_DebtFinancing     345,359,000atax_DebtFinancing
Adverse change rate 10.00%atax_AdverseChangeRate      
10% unrealized loss 32,600,000atax_A10UnrealizedLoss      
Concord at Gulfgate [Member]        
Number of Units in Real Estate Property 288us-gaap_NumberOfUnitsInRealEstateProperty
/ dei_EntityByLocationAxis
= atax_ConcordatGulfgateMember
     
Heritage Square [Member]        
Cost adjusted for pay-downs 11,705,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_HeritageSquareMember
    11,705,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_HeritageSquareMember
Available-For-Sale Securities, Gross Unrealized Loss MTM 0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_HeritageSquareMember
    0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_HeritageSquareMember
Bruton Apartments [Member]        
Available-for-sale Securities, Amortized Cost Basis, Held in Trust 18,145,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_BrutonApartmentsMember
[1]      
Mortgage revenue bonds held in trust, at fair value 19,443,819atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_BrutonApartmentsMember
[1]      
Live 929 Apartments [Member]        
Available-for-sale Securities, Amortized Cost Basis, Held in Trust 40,874,690atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_Live929ApartmentsMember
[1]     40,895,739atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_Live929ApartmentsMember
[1]
Mortgage revenue bonds held in trust, at fair value 45,029,467atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_Live929ApartmentsMember
[1]     44,693,484atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_Live929ApartmentsMember
[1]
Decatur-Angle [Member]        
Available-for-sale Securities, Amortized Cost Basis, Held in Trust 23,000,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_DecaturAngleMember
[1]     23,000,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_DecaturAngleMember
[1]
Mortgage revenue bonds held in trust, at fair value 23,727,260atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_DecaturAngleMember
[1]     23,919,540atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_DecaturAngleMember
[1]
Lost Creek [Member]        
Proceeds from Sale of Available-for-sale Securities     18,700,000us-gaap_ProceedsFromSaleOfAvailableForSaleSecurities
/ dei_EntityByLocationAxis
= atax_LostCreekMember
 
Copper Gate [Member]        
Available-for-sale Securities, Amortized Cost Basis, Held in Trust 5,220,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_CopperGateMember
[2]     5,220,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_CopperGateMember
[2]
Mortgage revenue bonds held in trust, at fair value 5,610,143atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_CopperGateMember
[2]     5,783,656atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_CopperGateMember
[2]
The Palms at Premier Park [Member]        
Available-for-sale Securities, Amortized Cost Basis, Held in Trust 20,125,232atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_ThePalmsatPremierParkMember
[2]     20,152,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_ThePalmsatPremierParkMember
[2]
Mortgage revenue bonds held in trust, at fair value 22,130,237atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_ThePalmsatPremierParkMember
[2]     22,832,619atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_ThePalmsatPremierParkMember
[2]
The Suites on Paseo [Member]        
Available-for-sale Securities, Amortized Cost Basis, Held in Trust 35,450,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_TheSuitesonPaseoMember
[1]     35,450,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_TheSuitesonPaseoMember
[1]
Mortgage revenue bonds held in trust, at fair value 38,351,583atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_TheSuitesonPaseoMember
[1]     38,643,691atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_TheSuitesonPaseoMember
[1]
Vantage at Harlingen [Member]        
Debt Instrument, Interest Rate, Stated Percentage 6.00%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ dei_EntityByLocationAxis
= atax_VantageatHarlingenMember
     
Cost adjusted for pay-downs 6,692,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_VantageatHarlingenMember
    6,692,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_VantageatHarlingenMember
Available-For-Sale Securities, Gross Unrealized Loss MTM 0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_VantageatHarlingenMember
    0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_VantageatHarlingenMember
Greens of Pine Glen [Member]        
Loans Payable 1,108,376us-gaap_LoansReceivableNet
/ dei_EntityByLocationAxis
= atax_GreensOfPineGlenMember
    1,081,342us-gaap_LoansReceivableNet
/ dei_EntityByLocationAxis
= atax_GreensOfPineGlenMember
Rennaisance [Member]        
Cost adjusted for pay-downs 12,675,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_RennaisanceMember
    12,675,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_RennaisanceMember
Available-For-Sale Securities, Gross Unrealized Loss MTM 0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_RennaisanceMember
    0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_RennaisanceMember
Avistar Portfolio [Member]        
Loans Payable 299,695us-gaap_LoansReceivableNet
/ dei_EntityByLocationAxis
= atax_AvistarPortfolioMember
    290,966us-gaap_LoansReceivableNet
/ dei_EntityByLocationAxis
= atax_AvistarPortfolioMember
Vantage at Judson [Member]        
Debt Instrument, Interest Rate, Stated Percentage 6.00%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ dei_EntityByLocationAxis
= atax_VantageAtJudsonMember
     
Cost adjusted for pay-downs 6,049,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_VantageAtJudsonMember
    6,049,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_VantageAtJudsonMember
Available-For-Sale Securities, Gross Unrealized Loss MTM 0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_VantageAtJudsonMember
    0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_VantageAtJudsonMember
Concord at Little York [Member]        
Number of Units in Real Estate Property 276us-gaap_NumberOfUnitsInRealEstateProperty
/ dei_EntityByLocationAxis
= atax_ConcordatLittleYorkMember
     
Concord at Williamcrest [Member]        
Number of Units in Real Estate Property 288us-gaap_NumberOfUnitsInRealEstateProperty
/ dei_EntityByLocationAxis
= atax_ConcordatWilliamcrestMember
     
Concord Portfolio [Member]        
TOB Financing 33,300,000atax_TobFinancing
/ dei_EntityByLocationAxis
= atax_ConcordPortfolioMember
     
Number of Available for Sale Securities, Held in a Trust 3atax_NumberOfAvailableForSaleSecuritiesHeldInTrust
/ dei_EntityByLocationAxis
= atax_ConcordPortfolioMember
     
Series A [Member] | Concord at Gulfgate [Member]        
Available-for-sale Securities, Amortized Cost Basis, Held in Trust 17,060,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_ConcordatGulfgateMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[1]      
Cost adjusted for pay-downs 17,100,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_ConcordatGulfgateMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
     
Mortgage revenue bonds held in trust, at fair value 18,477,004atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_ConcordatGulfgateMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[1]      
Series A [Member] | Harden Ranch [Member]        
Available-for-sale Securities, Amortized Cost Basis, Held in Trust 6,960,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_HardenRanchMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]     6,960,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_HardenRanchMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]
Mortgage revenue bonds held in trust, at fair value 7,583,129atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_HardenRanchMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]     7,471,421atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_HardenRanchMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]
Series A [Member] | Tyler Park Apartments [Member]        
Available-for-sale Securities, Amortized Cost Basis, Held in Trust 6,075,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_TylerParkApartmentsMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]     6,075,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_TylerParkApartmentsMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]
Mortgage revenue bonds held in trust, at fair value 6,458,329atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_TylerParkApartmentsMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]     6,420,060atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_TylerParkApartmentsMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]
Series A [Member] | Westside Village Market [Member]        
Available-for-sale Securities, Amortized Cost Basis, Held in Trust 3,970,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_WestsideVillageMarketMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]     3,970,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_WestsideVillageMarketMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]
Mortgage revenue bonds held in trust, at fair value 4,220,505atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_WestsideVillageMarketMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]     4,195,496atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_WestsideVillageMarketMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]
Series A [Member] | Greens of Pine Glen [Member]        
Available-for-sale Securities, Amortized Cost Basis, Held in Trust 8,348,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_GreensOfPineGlenMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]     8,366,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_GreensOfPineGlenMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]
Mortgage revenue bonds held in trust, at fair value 9,291,736atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_GreensOfPineGlenMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]     9,371,119atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_GreensOfPineGlenMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]
Series A [Member] | Avistar on the Boulevard [Member]        
Available-for-sale Securities, Amortized Cost Basis, Held in Trust 16,525,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_AvistarOnBoulevardMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]     16,525,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_AvistarOnBoulevardMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]
Mortgage revenue bonds held in trust, at fair value 18,320,997atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_AvistarOnBoulevardMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]     18,943,599atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_AvistarOnBoulevardMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]
Series A [Member] | Avistar at Chase Hill [Member]        
Available-for-sale Securities, Amortized Cost Basis, Held in Trust 10,000,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_AvistarAtChaseHillMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]     10,000,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_AvistarAtChaseHillMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]
Mortgage revenue bonds held in trust, at fair value 11,226,837atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_AvistarAtChaseHillMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]     11,196,800atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_AvistarAtChaseHillMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]
Series A [Member] | Avistar at the Crest [Member]        
Available-for-sale Securities, Amortized Cost Basis, Held in Trust 9,700,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_AvistarAtCrestMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]     9,700,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_AvistarAtCrestMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]
Mortgage revenue bonds held in trust, at fair value 10,754,230atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_AvistarAtCrestMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]     11,119,692atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_AvistarAtCrestMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[2]
Series A [Member] | Concord at Little York [Member]        
Available-for-sale Securities, Amortized Cost Basis, Held in Trust 12,480,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_ConcordatLittleYorkMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[1]      
Cost adjusted for pay-downs 12,500,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_ConcordatLittleYorkMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
     
Mortgage revenue bonds held in trust, at fair value 13,300,061atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_ConcordatLittleYorkMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[1]      
Series A [Member] | Concord at Williamcrest [Member]        
Available-for-sale Securities, Amortized Cost Basis, Held in Trust 18,020,000atax_AvailableForSaleSecuritiesAmortizedCostBasisHeldInTrust
/ dei_EntityByLocationAxis
= atax_ConcordatWilliamcrestMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[1]      
Cost adjusted for pay-downs 18,000,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_ConcordatWilliamcrestMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
     
Mortgage revenue bonds held in trust, at fair value 19,204,094atax_AvailableForSaleSecuritiesFairValueDisclosureHeldInTrust
/ dei_EntityByLocationAxis
= atax_ConcordatWilliamcrestMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
[1]      
Series A [Member] | Concord Portfolio [Member]        
Debt Instrument, Maturity Date Feb. 01, 2032      
Debt Instrument, Interest Rate, Stated Percentage 6.00%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ dei_EntityByLocationAxis
= atax_ConcordPortfolioMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesAMember
     
Series B [Member] | Concord at Gulfgate [Member]        
Cost adjusted for pay-downs 2,125,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_ConcordatGulfgateMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
     
Available-For-Sale Securities, Gross Unrealized Loss MTM 0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_ConcordatGulfgateMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
     
Series B [Member] | Harden Ranch [Member]        
Cost adjusted for pay-downs 2,340,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_HardenRanchMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
    2,340,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_HardenRanchMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
Available-For-Sale Securities, Gross Unrealized Loss MTM 2,176atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_HardenRanchMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
    1,501atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_HardenRanchMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
Series B [Member] | Tyler Park Apartments [Member]        
Cost adjusted for pay-downs 2,025,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_TylerParkApartmentsMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
    2,025,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_TylerParkApartmentsMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
Available-For-Sale Securities, Gross Unrealized Loss MTM 8,991atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_TylerParkApartmentsMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
    17,395atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_TylerParkApartmentsMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
Series B [Member] | Westside Village Market [Member]        
Cost adjusted for pay-downs 1,430,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_WestsideVillageMarketMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
    1,430,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_WestsideVillageMarketMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
Available-For-Sale Securities, Gross Unrealized Loss MTM 6,349atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_WestsideVillageMarketMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
    686atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_WestsideVillageMarketMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
Series B [Member] | The Suites on Paseo [Member]        
Mortgage revenue bonds, at fair value 35,600,000us-gaap_AvailableForSaleSecuritiesNoncurrent
/ dei_EntityByLocationAxis
= atax_TheSuitesonPaseoMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
     
Cost adjusted for pay-downs 5,500,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_TheSuitesonPaseoMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
     
Available-For-Sale Securities, Gross Unrealized Loss MTM 0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_TheSuitesonPaseoMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
     
Series B [Member] | Greens of Pine Glen [Member]        
Cost adjusted for pay-downs 945,059us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_GreensOfPineGlenMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
    945,638us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_GreensOfPineGlenMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
Available-For-Sale Securities, Gross Unrealized Loss MTM 0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_GreensOfPineGlenMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
    0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_GreensOfPineGlenMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
Series B [Member] | Avistar on the Boulevard [Member]        
Cost adjusted for pay-downs 451,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_AvistarOnBoulevardMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
    451,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_AvistarOnBoulevardMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
Available-For-Sale Securities, Gross Unrealized Loss MTM 0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_AvistarOnBoulevardMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
    0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_AvistarOnBoulevardMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
Series B [Member] | Avistar at Chase Hill [Member]        
Cost adjusted for pay-downs 965,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_AvistarAtChaseHillMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
    965,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_AvistarAtChaseHillMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
Available-For-Sale Securities, Gross Unrealized Loss MTM 0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_AvistarAtChaseHillMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
    0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_AvistarAtChaseHillMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
Series B [Member] | Avistar at the Crest [Member]        
Cost adjusted for pay-downs 759,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_AvistarAtCrestMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
    759,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_AvistarAtCrestMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
Available-For-Sale Securities, Gross Unrealized Loss MTM 0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_AvistarAtCrestMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
    0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_AvistarAtCrestMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
Series B [Member] | Concord at Little York [Member]        
Cost adjusted for pay-downs 960,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_ConcordatLittleYorkMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
     
Available-For-Sale Securities, Gross Unrealized Loss MTM 0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_ConcordatLittleYorkMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
     
Series B [Member] | Concord at Williamcrest [Member]        
Cost adjusted for pay-downs 2,800,000us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ dei_EntityByLocationAxis
= atax_ConcordatWilliamcrestMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
     
Available-For-Sale Securities, Gross Unrealized Loss MTM 0atax_AvailableForSaleSecuritiesGrossUnrealizedLossMTM
/ dei_EntityByLocationAxis
= atax_ConcordatWilliamcrestMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
     
Series B [Member] | Concord Portfolio [Member]        
Debt Instrument, Maturity Date Mar. 01, 2032      
Debt Instrument, Interest Rate, Stated Percentage 12.00%us-gaap_DebtInstrumentInterestRateStatedPercentage
/ dei_EntityByLocationAxis
= atax_ConcordPortfolioMember
/ invest_InvestmentSecuritiesSeriesAxis
= us-gaap_SeriesBMember
     
Minimum [Member] | Woodlynn Village and Avistar at the Crest [Member]        
Unrealized Loss Position for Available-for-sale Securities 12 months      
Effective rate - maximum [Member]        
Effective rate 9.60%atax_EffectiveRate
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= atax_EffectiveRateMaximumMember
    8.30%atax_EffectiveRate
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= atax_EffectiveRateMaximumMember
Effective rate - minimum [Member]        
Effective rate 4.80%atax_EffectiveRate
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= atax_EffectiveRateMinimumMember
    4.70%atax_EffectiveRate
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= atax_EffectiveRateMinimumMember
10% adverse [Member] | Effective rate - maximum [Member]        
Effective rate 10.50%atax_EffectiveRate
/ us-gaap_InformationByCategoryOfDebtSecurityAxis
= atax_A10AdverseMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= atax_EffectiveRateMaximumMember
     
10% adverse [Member] | Effective rate - minimum [Member]        
Effective rate 5.20%atax_EffectiveRate
/ us-gaap_InformationByCategoryOfDebtSecurityAxis
= atax_A10AdverseMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= atax_EffectiveRateMinimumMember
     
TOB Facility-1 [Member]        
Debt, Weighted Average Interest Rate 1.10%us-gaap_DebtWeightedAverageInterestRate
/ us-gaap_DebtInstrumentAxis
= atax_TobFacility1Member
     
Mortgage revenue bonds [Member]        
Debt, Weighted Average Interest Rate 6.00%us-gaap_DebtWeightedAverageInterestRate
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_AvailableforsaleSecuritiesMember
     
Number of Units in Real Estate Property 7,379us-gaap_NumberOfUnitsInRealEstateProperty
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_AvailableforsaleSecuritiesMember
     
Trading Securities [Member]        
Debt financing $ 196,985,000atax_DebtFinancing
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_TradingAccountAssetsMember
    $ 174,250,000atax_DebtFinancing
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_TradingAccountAssetsMember
CALIFORNIA        
Percentage of Available for Sale Securities by Location 19.00%atax_PercentageofAvailableforSaleSecuritiesbyLocation
/ invest_InvestmentGeographicRegionAxis
= stpr_CA
    18.00%atax_PercentageofAvailableforSaleSecuritiesbyLocation
/ invest_InvestmentGeographicRegionAxis
= stpr_CA
TEXAS        
Percentage of Available for Sale Securities by Location 45.00%atax_PercentageofAvailableforSaleSecuritiesbyLocation
/ invest_InvestmentGeographicRegionAxis
= stpr_TX
    38.00%atax_PercentageofAvailableforSaleSecuritiesbyLocation
/ invest_InvestmentGeographicRegionAxis
= stpr_TX
[1] Mortgage revenue bonds held by Deutsche Bank in a secured financing transaction, Note 9
[2] Mortgage revenue bonds owned by ATAX TEBS II, LLC, Note 9