Investments In and Advances to Partnerships - Apartment Complexes Owned (Details)	6 Months Ended
	Jun. 30, 2013 partnership property	Jun. 30, 2012 partnership property
Schedule of Equity Method Investments [Line Items]
Number of Local Partnership investments	2
Chestnut Apartments [Member] | Fresno, California [Member]
Schedule of Equity Method Investments [Line Items]
Number of units in apartment complexes	90
Westwood Village [Member] | New Haven, Connecticut [Member]
Schedule of Equity Method Investments [Line Items]
Number of units in apartment complexes	48
Local Partnerships [Member]
Schedule of Equity Method Investments [Line Items]
Number of Local Partnership investments	2	6
Number of apartment complexes owned	2	6