Mortgage-Backed Securities Narrative Tagging (Details) (USD $)	3 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Tolerable Range of Difference in Valuation	0.00%
Adverse change rate	10.00%atax_AdverseChangeRate
Unrealized Loss	$ (17,516)	$ (19,582)
Available for Sale Securities, not Including Premiums		59,308,398
Effective rate - minimum [Member]
Effective rate	4.80%	4.70%
Effective rate - maximum [Member]
Effective rate	9.60%	8.30%
Trust Portfolio--MBS Bonds [Member]
Adverse change rate	10.00%
Unrealized Loss	(476,037)	(526,083)
Number of Available for Sale Securities, Mortgage Backed Securities	3
Available for Sale Securities, not Including Premiums	14,765,000
Trust Portfolio--MBS Bonds [Member] \| Effective rate - minimum [Member]
Effective rate	3.60%	3.70%
Trust Portfolio--MBS Bonds [Member] \| Effective rate - maximum [Member]
Effective rate	5.20%	5.20%
10% adverse [Member] \| Effective rate - minimum [Member]
Effective rate	5.20%
10% adverse [Member] \| Effective rate - maximum [Member]
Effective rate	10.50%
10% adverse [Member] \| Trust Portfolio--MBS Bonds [Member]
Available-for-sale Securities, Gross Unrealized Loss	801,000
10% adverse [Member] \| Trust Portfolio--MBS Bonds [Member] \| Effective rate - minimum [Member]
Effective rate	4.00%
10% adverse [Member] \| Trust Portfolio--MBS Bonds [Member] \| Effective rate - maximum [Member]
Effective rate	5.80%
LIFERS [Member] \| Trust Portfolio--MBS Bonds [Member]
Available for Sale Securities, not Including Premiums	2,800,000
SPEARS [Member] \| Trust Portfolio--MBS Bonds [Member]
TOB Financing	$ 11,900,000

Adverse change rate - effective rate if 10% adverse change in market occurs

No definition available.

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- Definition

Amount of unrealized loss before deducting unrealized gain on investments in available-for-sale securities.

+ References

No definition available.

+ Details

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- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. This does not include premiums.

+ References

No definition available.

+ Details

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- Definition

Effective rate - the effective rate for the available for sale securities held in the portfolio

+ References

No definition available.

+ Details

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

- Definition

Number of Available for Sale Securities, Mortgage Backed Securities

+ References

No definition available.

+ Details

Name:	atax_NumberOfAvailableForSaleSecuritiesMortgageBackedSecurities
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Data Type:	xbrli:integerItemType
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- Definition

TOB Financing - Tender Option Bond Financing Facility

+ References

No definition available.

+ Details

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Namespace Prefix:	atax_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

- Definition

The percentage of difference of the valuation of an asset between the Company and a third party.

+ References

No definition available.

+ Details

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

- Definition

Amount of unrealized loss before deducting unrealized gain on investments in available-for-sale securities.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

+ Details

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- Details

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- Details

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- Details

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- Details

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- Details

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