Investments In and Advances to Partnerships - Apartment Complexes Owned (Details)	3 Months Ended
	Mar. 31, 2013 partnership property	Mar. 31, 2012 partnership property
Chestnut Apartments [Member] | Fresno, California [Member]
Schedule of Equity Method Investments [Line Items]
Number of units in apartment complexes	90
New Sharon Woods [Member] | Deptford, New Jersey [Member]
Schedule of Equity Method Investments [Line Items]
Number of units in apartment complexes	50
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 Partnerships with limited equity interests	3	6
Number of apartment complexes owned	3	6