Co-investments (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	$ 579,654,000		$ 571,345,000
Preferred return rate (in hundredths)	9.50%
Preferred equity redemption	9,700,000
Early redemption penalties	400,000
Balance sheets: [Abstract]
Rental properties and real estate under development	65,568,000		66,851,000
Other Liabilities	22,625,000		22,167,000
Statement of operations: [Abstract]
Interest expense	(25,211,000)	(24,658,000)
General and administrative	(6,626,000)	(5,400,000)
Depreciation and Amortization	(2,930,000)	(2,871,000)
Membership interest in Wesco I [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	143,051,000		143,874,000
Partnership interest in Fund II [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	27,121,000		53,601,000
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	18,714,000		18,752,000
Membership interest in Wesco III [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	9,821,000		9,941,000
Total operating co investments [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	198,707,000		226,168,000
Membership interests in limited liability companies that own and are developing Epic, Connolly Station, Mosso I. & II. , and Elkhorn [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	221,247,000		186,362,000
Membership interest in a limited liability company that owns and is developing Expo [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	16,928,000		16,552,000
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]
Preferred return rate (in hundredths)	10.00%
Total development co investments [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	238,175,000		202,914,000
Membership interest in Wesco II that owns a preferred equity interest in Park Merced with a preferred return of 10.1% [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	92,550,000		91,843,000
Preferred return rate (in hundredths)	10.10%
Preferred interest in limited liability company that owns an apartment community in downtown Los Angeles with a preferred return 10%
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	13,068,000		13,068,000
Preferred interests in related party limited liability companies that owns Sage at Cupertino with a preferred return of 9.5% [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	15,055,000		14,438,000
Preferred return rate (in hundredths)	9.50%
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	13,232,000		13,175,000
Preferred return rate (in hundredths)	13.00%
Preferred interests in limited liability companies that own apartment communities in downtown Los Angeles with preferred returns of 9% repaid in March 2013 [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	0		9,739,000
Preferred return rate (in hundredths)	9.00%
Preferred interest in related limited liability company that owns an apartment deveopment in Redwood City with a preferred return of 9.5% [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	8,867,000		0
Preferred return rate (in hundredths)	9.50%
Total preferred interest investments [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	142,772,000		142,263,000
Preferred equity Interest investment [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	8,600,000
Total co investment [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	579,654,000		571,345,000
Balance sheets: [Abstract]
Rental properties and real estate under development	1,709,065,000		1,745,147,000
Other Assets	85,039,000		168,061,000
Total assets	1,794,104,000		1,913,208,000
Debt	785,459,000		820,895,000
Other Liabilities	54,877,000		91,922,000
Equity	953,768,000		1,000,391,000
Total liabilities and equity	1,794,104,000		1,913,208,000
Company's share of equity	579,654,000		571,345,000
Statement of operations: [Abstract]
Property revenues	27,859,000	34,323,000
Property operating expenses	(9,828,000)	(13,137,000)
Net property operating income	18,031,000	21,186,000
Interest expense	(6,778,000)	(8,545,000)
General and administrative	(1,514,000)	(796,000)
Depreciation and Amortization	(11,019,000)	(13,896,000)
Net Loss	(1,280,000)	(2,051,000)
Company's share of net income (loss)	$ 4,211,000	$ 2,340,000