Identified Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Gross amount	$ 404,473		$ 404,473		$ 415,261
Accumulated amortization	(194,463)		(194,463)		(187,360)
Net	210,010		210,010		227,901
Gross amount	600,722		600,722		643,488
Accumulated amortization	(311,197)		(311,197)		(325,340)
Net	289,525		289,525		$ 318,148
Below Market Leases Net Of Above Market Leases [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	12,301	$ 13,378	29,808	$ 25,828
2017	45,361		45,361
2018	44,101		44,101
2019	31,937		31,937
2020	23,365		23,365
2021	18,287		18,287
Other Identified Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	8,066	5,309	15,859	11,494
2017	24,795		24,795
2018	20,541		20,541
2019	16,202		16,202
2020	12,404		12,404
2021	11,032		11,032
Tenant Under Ground Leases [Member]
Finite-Lived Intangible Assets [Line Items]
Amortization of Intangible Assets	458	$ 458	916	$ 916
2017	1,832		1,832
2018	1,832		1,832
2019	1,832		1,832
2020	1,832		1,832
2021	$ 1,832		$ 1,832