Unconsolidated Real Estate Affiliates (Details 2) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
SUMMARIZED COMBINED STATEMENTS OF OPERATIONS-UNCONSOLIDATED REAL ESTATE AFFILIATES
Total revenues	$ 19,824,000	$ 18,086,000	$ 19,401,000	$ 19,890,000	$ 20,689,000	$ 20,211,000	$ 20,831,000	$ 20,185,000	$ 77,201,000	$ 81,916,000	$ 80,033,000
Total operating expenses									59,463,000	56,992,000	58,018,000
Operating income	4,096,000	3,000,000	4,979,000	5,663,000	6,620,000	4,776,000	7,133,000	6,395,000	17,738,000	24,924,000	22,015,000
Total other expenses									(8,069,000)	28,212,000	30,046,000
Unconsolidated Real Estate Affiliates [Member]
SUMMARIZED COMBINED STATEMENTS OF OPERATIONS-UNCONSOLIDATED REAL ESTATE AFFILIATES
Total revenues									25,379	25,229	30,875
Total operating expenses									17,483	18,450	23,382
Operating income									7,896	6,779	7,493
Total other expenses									7,827	8,298	9,872
Net income (loss)									$ 69	$ (1,519)	$ (2,379)