Co-Investments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	$ 401,531		$ 383,412
Preferred return rate (in hundredths)	13.00%		13.00%
Balance sheets: [Abstract]
Rental properties and real estate under development	45,632		44,280
Other Liabilities	20,446		20,528
Statement of operations: [Abstract]
Interest expense	24,658	21,811
General and administrative	5,400	5,274
Depreciation and Amortization	2,871	2,851
Membership interest in Wesco I [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	74,697		75,588
Partnership interest in Fund II [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	64,735		64,294
Membership interest in a limited liability company that owns Essex Skyline at MacArthur Place [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	22,424		24,063
Total operating co-investments [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	161,856		163,945
Membership interests in limited liability companies that own and are developing Cadence, West Dublin, and Elkhorn [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	81,499		62,897
Membership interest in a limited liability company that owns and is developing Queen Anne [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	18,273		17,981
Membership interests in limited liability companies that own and are developing Fountain at La Brea and Santa Monica at La Brea [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	15,381		15,194
Total development co-investments [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	115,153		96,072
Membership interest in Wesco II that owns a preferred equity interest in Park Merced with a perferred return of 10.1% [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	89,065		88,075
Preferred return rate (in hundredths)	10.10%		10.10%
Preferred interests in limited liability companies that own apartment communities in downtown Los Angeles with preferred returns of 9% and 10% [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	22,792		22,792
Preferred return rate (in hundredths)	9.00%		10.00%
Preferred interest in a related limited liability company that owns Madison Park at Anaheim with a preferred return of 13% [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	12,665		12,528
Total preferred interest investments [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	124,522		123,395
Total co investment [Member]
Balance sheets: [Abstract]
Rental properties and real estate under development	1,506,352		1,659,078
Other Assets	86,511		63,847
Total assets	1,592,863		1,722,925
Debt	904,311		900,095
Other Liabilities	56,144		48,518
Equity	632,408		774,312
Total liabilities and equity	1,592,863		1,722,925
Company's share of equity	401,531		383,412
Statement of operations: [Abstract]
Property revenues	34,323	18,512
Property operating expenses	(13,136)	(7,976)
Net property operating income	21,187	10,536
Interest expense	(8,545)	(4,861)
General and administrative	(169)	(984)
Depreciation and Amortization	(13,761)	(8,063)
Net Loss	(1,288)	(3,372)
Company's share of net income (loss)	$ 2,340	$ (1,373)