Co-investments (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	$ 618,259,000		$ 618,259,000		$ 571,345,000
Preferred return rate (in hundredths)			9.50%
Preferred equity redemption	13,100,000		9,700,000
Early redemption penalties	500,000		400,000
Balance sheets: [Abstract]
Rental properties and real estate under development	70,242,000		70,242,000		66,851,000
Other Liabilities	22,432,000		22,432,000		22,167,000
Statement of operations: [Abstract]
Interest expense	(26,325,000)	(24,659,000)	(51,536,000)	(49,316,000)
General and administrative	(6,224,000)	(5,764,000)	(12,850,000)	(11,164,000)
Depreciation and Amortization	(3,002,000)	(2,882,000)	(5,932,000)	(5,754,000)
Membership interest in Wesco I [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	142,704,000		142,704,000		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	23,945,000		23,945,000		53,601,000
Membership interest in Wesco III [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	37,917,000		37,917,000		9,941,000
Total operating co investments [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	223,555,000		223,555,000		226,168,000
Statement of operations: [Abstract]
Net Loss			(2,106,000)	(1,435,000)
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	229,095,000		229,095,000		186,362,000
Membership interests 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	18,989,000		18,989,000		18,752,000
Membership interests in limited liability companies that own and are developing The Huxley and The Dylan [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	17,381,000		17,381,000		16,552,000
Preferred return rate (in hundredths)			10.00%
Membership interests in limited liability companies that owns and is developing One South Market [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	16,908,000		16,908,000		0
Total development co investments [Member]
Investments in joint ventures accounted for under the equity method of accounting [Abstract]
Total co-investment	263,384,000		263,384,000		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	93,273,000		93,273,000		91,843,000
Preferred return rate (in hundredths)			10.10%
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	15,493,000		15,493,000		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	13,536,000		13,536,000		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		0		22,807,000
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	9,018,000		9,018,000		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	131,320,000		131,320,000		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		8,600,000
Total co investment [Member]
Balance sheets: [Abstract]
Rental properties and real estate under development	1,769,246,000		1,769,246,000		1,745,147,000
Other Assets	65,238,000		65,238,000		168,061,000
Total assets	1,834,484,000		1,834,484,000		1,913,208,000
Debt	663,830,000		663,830,000		820,895,000
Other Liabilities	147,356,000		147,356,000		91,922,000
Equity	1,023,298,000		1,023,298,000		1,000,391,000
Total liabilities and equity	1,834,484,000		1,834,484,000		1,913,208,000
Company's share of equity	618,259,000		618,259,000		571,345,000
Statement of operations: [Abstract]
Property revenues	26,258,000	28,233,000	54,117,000	62,556,000
Property operating expenses	(9,874,000)	(10,029,000)	(19,702,000)	(23,166,000)
Net property operating income	16,384,000	18,204,000	34,415,000	39,390,000
Interest expense	(6,094,000)	(7,792,000)	(12,872,000)	(16,337,000)
General and administrative	(1,539,000)	(920,000)	(3,053,000)	(1,716,000)
Depreciation and Amortization	(9,577,000)	(8,876,000)	(20,596,000)	(22,772,000)
Net Loss	(826,000)	616,000
Company's share of net income (loss)	$ 7,282,000	$ 3,111,000	$ 11,493,000	$ 5,451,000