Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Schedule of segments operating activity
Segment profit	$ 35,913	$ 31,326	$ 72,264	$ 62,040
Segment profit	17,250	13,526	34,583	28,899
Total Retail [Member]
Schedule of segments operating activity
Property revenue	22,452	22,077	44,143	43,429
Property expense	(6,094)	(6,007)	(11,820)	(11,452)
Segment profit	16,358	16,070	32,323	31,977
Total Office [Member]
Schedule of segments operating activity
Property revenue	19,705	14,169	39,181	27,432
Property expense	(6,505)	(5,110)	(12,651)	(8,820)
Segment profit	13,200	9,059	26,530	18,612
Total Multifamily [Member]
Schedule of segments operating activity
Property revenue	3,509	3,492	7,051	6,785
Property expense	(1,565)	(1,426)	(2,879)	(2,587)
Segment profit	1,944	2,066	4,172	4,198
Total Mixed-Use [Member]
Schedule of segments operating activity
Property revenue	12,143	11,362	24,472	20,337
Property expense	(7,732)	(7,231)	(15,233)	(13,084)
Segment profit	$ 4,411	$ 4,131	$ 9,239	$ 7,253