Real Estate Summary of Real Estate Investments (Details) - USD ($) $ in Thousands		Dec. 31, 2014	Dec. 31, 2013
Real Estate Properties [Line Items]
Construction in progress		$ 195,736	$ 67,389
Total Real estate, at cost		2,136,824	1,995,417
Accumulated depreciation		(361,424)	(318,581)
Net real estate		1,775,400	1,676,836
Total Retail
Real Estate Properties [Line Items]
Net real estate		639,456	651,707
Total Office
Real Estate Properties [Line Items]
Net real estate		757,854	750,890
Total Multifamily
Real Estate Properties [Line Items]
Net real estate		182,468	74,612
Total Mixed-Use
Real Estate Properties [Line Items]
Net real estate		195,622	199,627
Real Estate Investment
Real Estate Properties [Line Items]
Land		494,103	493,725
Buildings		1,289,499	1,282,580
Land improvements		53,720	52,793
Tenant improvements		108,310	99,362
Furniture, fixtures, and equipment		12,456	16,568
Construction in progress	[1]	178,736	50,389
Total Real estate, at cost		2,136,824	1,995,417
Accumulated depreciation		(361,424)	(318,581)
Net real estate		1,775,400	1,676,836
Real Estate Investment | Total Retail
Real Estate Properties [Line Items]
Land		248,386	248,008
Buildings		500,088	499,091
Land improvements		39,999	39,892
Tenant improvements		50,504	46,649
Furniture, fixtures, and equipment		491	489
Construction in progress		5,327	2,673
Total Real estate, at cost		844,795	836,802
Accumulated depreciation		(205,339)	(185,095)
Net real estate		639,456	651,707
Real Estate Investment | Total Office
Real Estate Properties [Line Items]
Land		143,575	143,575
Buildings		621,343	618,077
Land improvements		8,273	7,528
Tenant improvements		56,127	51,016
Furniture, fixtures, and equipment		750	517
Construction in progress		31,878	14,189
Total Real estate, at cost		861,946	834,902
Accumulated depreciation		(104,092)	(84,012)
Net real estate		757,854	750,890
Real Estate Investment | Total Multifamily
Real Estate Properties [Line Items]
Land		25,507	25,507
Buildings		42,270	42,270
Land improvements		3,085	3,010
Tenant improvements		0	0
Furniture, fixtures, and equipment		5,832	5,482
Construction in progress		141,205	32,252
Total Real estate, at cost		217,899	108,521
Accumulated depreciation		(35,431)	(33,909)
Net real estate		182,468	74,612
Real Estate Investment | Total Mixed-Use
Real Estate Properties [Line Items]
Land		76,635	76,635
Buildings		125,798	123,142
Land improvements		2,363	2,363
Tenant improvements		1,679	1,697
Furniture, fixtures, and equipment		5,383	10,080
Construction in progress		326	1,275
Total Real estate, at cost		212,184	215,192
Accumulated depreciation		(16,562)	(15,565)
Net real estate		$ 195,622	$ 199,627

[1] Land related to held for development and construction in progress is included in the Held for Development and Construction in Progress classifications on the consolidated balance sheets.