Summary of Significant Accounting Policies Deferred Leasing and Other Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Deferred Leasing and Other [Abstract]
Deferred Costs, Leasing, Gross	$ 302,282	$ 301,173
Finite-Lived Intangible Asset, Acquired-in-Place Leases	289,518	325,294
Deferred Leasing Costs and Finite Lived Intangible Assets Acquired, gross	591,800	626,467
Deferred Costs, Leasing, Accumulated Amortization	(106,912)	(104,916)
Finite-Lived Intangible Assets, Accumulated Amortization	(138,514)	(133,916)
Deferred Costs, Leasing, Net	346,374	$ 387,635
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	33,486
Finite-Lived Intangible Assets, Amortization Expense, Year Two	28,103
Finite-Lived Intangible Assets, Amortization Expense, Year Three	21,704
Finite-Lived Intangible Assets, Amortization Expense, Year Four	17,302
Finite-Lived Intangible Assets, Amortization Expense, Year Five	12,423
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	32,524
Finite-Lived Intangible Assets, Net	145,542
Net Charge to Rental Income Year One	1,139
Net Charge to Rental Income Year Two	966
Net Charge to Rental Income Year Three	863
Net Charge to Rental Income Year Four	712
Net Charge to Rental Income Year Five	633
Net Charge to Rental Income After Year Five	1,149
Net Charge to Rental Income	$ 5,462