Governmental Issuer Loans - Additional Information (Details) - Scharbauer Flats Apartments [Member]	12 Months Ended
Dec. 31, 2020
Governmental Issuer Loans [Line Items]
Percentage of payment of principal and accrued interest on governmental issuer loans at origination	100.00%
Percentage of decrease in principal and interest payment upon receipt of the certificate of occupancy	50.00%
Percentage of decrease in principal and interest payment upon achievement of 90% occupancy	25.00%

Percentage of decrease in principal and interest payment upon achievement of ninety percent occupancy.

No definition available.

Name:	atax_PercentageOfDecreaseInPrincipalAndInterestPaymentUponAchievementOfNinetyPercentOccupancy
Namespace Prefix:	atax_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration