Real Estate and Accumulated Depreciation (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Real Estate
Balance at beginning of period	$ 363,832	$ 308,499	$ 249,078
Additions during the period:
Transfer (to) from discontinued operations	(10,058)	(1,639)	(3,970)
Impairments during the period	(3,260)	(7,600)	(2,720)
Disposal of fully amortized assets	(297)	(168)	(1,004)
Balance at end of period	421,989	363,832	308,499
Accumulated Depreciation
Balance at beginning of period	44,556	36,232	31,269
Additions charged to operating expenses	11,207	8,644	6,399
Transfer (to) from discontinued operations, net	(3,913)	(152)	(432)
Disposal of fully amortized assets	(297)	(168)	(1,004)
Balance at end of period	51,553	44,556	36,232
Land [Member]
Additions during the period:
Other additions			9,408
Buildings and improvements [Member]
Additions during the period:
Other additions	12,417	11,962	6,121
Consolidation of 450 West 14th Street [Member]
Additions during the period:
Other additions	(26)	52,778
Consolidation of Deer Valley [Member]
Additions during the period:
Other additions			8,188
Consolidation of Newbury Apartments [Member]
Additions during the period:
Other additions			25,254
Consolidation of Crossroads II [Member]
Additions during the period:
Other additions			7,983
Purchase of Crossroads I [Member]
Additions during the period:
Other additions			7,441
Waterford [Member]
Additions during the period:
Purchase	20,565
Lake Brandt [Member]
Additions during the period:
Purchase	18,443
Cerritos [Member]
Additions during the period:
Purchase	20,304
Churchill [Member]
Additions during the period:
Proceeds from sale of Churchill	$ (629)