Real Estate Summary of Real Estate Investments (Details) - USD ($) $ in Thousands		Dec. 31, 2015	Dec. 31, 2014
Real Estate Properties [Line Items]
Construction in progress		$ 73,121	$ 195,736
Total Real estate, at cost		2,246,028	2,136,824
Accumulated depreciation		(411,166)	(361,424)
Net real estate		1,834,862	1,775,400
Total Retail
Real Estate Properties [Line Items]
Net real estate		638,893	639,456
Total Office
Real Estate Properties [Line Items]
Net real estate		796,773	757,854
Real Estate Investment
Real Estate Properties [Line Items]
Land		490,494	494,103
Buildings		1,501,459	1,289,499
Land improvements		54,119	53,720
Tenant improvements		120,719	108,310
Furniture, fixtures, and equipment		15,065	12,456
Construction in progress	[1]	64,172	178,736
Total Real estate, at cost		2,246,028	2,136,824
Accumulated depreciation		(411,166)	(361,424)
Net real estate		1,834,862	1,775,400
Real Estate Investment | Total Retail
Real Estate Properties [Line Items]
Land		245,588	248,386
Buildings		500,075	500,088
Land improvements		40,203	39,999
Tenant improvements		54,993	50,504
Furniture, fixtures, and equipment		491	491
Construction in progress		20,817	5,327
Total Real estate, at cost		862,167	844,795
Accumulated depreciation		(223,274)	(205,339)
Net real estate		638,893	639,456
Real Estate Investment | Total Office
Real Estate Properties [Line Items]
Land		143,575	143,575
Buildings		665,431	621,343
Land improvements		8,273	8,273
Tenant improvements		63,880	56,127
Furniture, fixtures, and equipment		1,265	750
Construction in progress		41,669	31,878
Total Real estate, at cost		924,093	861,946
Accumulated depreciation		(127,320)	(104,092)
Net real estate		796,773	757,854
Real Estate Investment | Total Multifamily
Real Estate Properties [Line Items]
Land		24,696	25,507
Buildings		210,093	42,270
Land improvements		3,280	3,085
Tenant improvements		0	0
Furniture, fixtures, and equipment		7,638	5,832
Construction in progress		1,649	141,205
Total Real estate, at cost		247,356	217,899
Accumulated depreciation		(38,626)	(35,431)
Net real estate		208,730	182,468
Real Estate Investment | Total Mixed-Use
Real Estate Properties [Line Items]
Land		76,635	76,635
Buildings		125,860	125,798
Land improvements		2,363	2,363
Tenant improvements		1,846	1,679
Furniture, fixtures, and equipment		5,671	5,383
Construction in progress		37	326
Total Real estate, at cost		212,412	212,184
Accumulated depreciation		(21,946)	(16,562)
Net real estate		$ 190,466	$ 195,622

[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.