Derivative, Maturity Date at a point in time

No definition available.

Name:	atax_DerivativeMaturityDateAtPointInTime
Namespace Prefix:	atax_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Deriviative at purchase price - The amount paid for the deriviative when it was purchased.

+ References

No definition available.

+ Details

Name:	atax_DeriviativeAtPurchasePrice
Namespace Prefix:	atax_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

effective rate - maximum - the maximum effective rate for the available for sale portfolio

+ References

No definition available.

+ Details

Name:	atax_EffectiveRateMaximum
Namespace Prefix:	atax_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of derivatives.

+ References

No definition available.

+ Details

Name:	atax_NumberOfDerivatives
Namespace Prefix:	atax_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Nominal or face amount used to calculate payments on the derivative asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5579245-113959

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

+ Details

Name:	us-gaap_DerivativeAssetNotionalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226016-175313

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (d)(2)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 8

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=d3e41678-113959

+ Details

Name:	us-gaap_DerivativeCollateralRightToReclaimCash
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=34720828&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (a),(c)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624163-113959

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=36459792&loc=SL20226000-175313

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeFixedInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of decrease in the fair value of derivatives recognized in the income statement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5618551-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (a),(c),(d),(e)

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624171-113959

+ Details

Name:	us-gaap_DerivativeLossOnDerivative
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_CounterpartyNameAxis=atax_BarclaysBankPLC1RoyalBankofCanada2andSMBCCapitalMarketsInc3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CounterpartyNameAxis=atax_BarclaysBankPLCBankofNewYorkMellonandRoyalBankofCanadaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CounterpartyNameAxis=atax_DeutscheBankMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CounterpartyNameAxis=atax_SMBCCapitalMarketsInc1and2Member
Namespace Prefix:
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Period Type:

Interest Rate Derivative Agreements Footnote Tagging (Details) (USD $)	12 Months Ended		3 Months Ended	9 Months Ended	3 Months Ended	9 Months Ended
	Dec. 31, 2014 derivatives	Dec. 31, 2013	Sep. 30, 2014	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2013	Sep. 30, 2010
Derivative [Line Items]
Number of Derivatives	9atax_NumberOfDerivatives
Derivative, Fixed Interest Rate						3.00%us-gaap_DerivativeFixedInterestRate
Derivative, Collateral, Right to Reclaim Cash						$ 500,000
Derivative, Loss on Derivative	2,000,000us-gaap_DerivativeLossOnDerivative	284,000,000us-gaap_DerivativeLossOnDerivative
Derivative Asset, Fair Value, Gross Asset	268,000	888,000,000
Barclays Bank PLC 1, Royal Bank of Canada-2 and SMBC Capital Markets, Inc-3 [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount			31,600,000	31,600,000
Derivative, Maturity Date at a point in time			Aug. 15, 2019
Derivative, Fixed Interest Rate			3.00%	3.00%
Deriviative at purchase price				991,000
SMBC Capital Markets, Inc 1 and 2 [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount					70,000,000
Derivative, Maturity Date at a point in time					Mar. 01, 2017
Derivative, Fixed Interest Rate					1.00%
Deriviative at purchase price					390,000
Barclays Bank PLC, Bank of New York Mellon, and Royal Bank of Canada [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount							31,900,000
Derivative, Fixed Interest Rate							3.00%
effective rate - maximum							4.90%
Deutsche Bank [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount						93,300,000
Derivative, Maturity Date at a point in time	Sep. 01, 2017					Sep. 01, 2017
Derivative, Fixed Interest Rate	1.50%					1.50%
Deriviative at purchase price	$ 793,000					$ 800,000