Summary of Significant Accounting Policies Deferred Leasing and Other Costs (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Leasing and Other [Abstract]
Deferred leasing costs	$ 333,706,000	$ 307,486,000
Acquired lease-related intangible assets	190,595,000	207,057,000
Deferred Leasing Costs and Finite Lived Intangible Assets Acquired, gross	524,301,000	514,543,000
Accumulated amortization - deferred leasing costs	(109,843,000)	(101,403,000)
Accumulated amortization - acquired lease-related intangible assets	(94,014,000)	(99,341,000)
Deferred Costs, Leasing, Net	320,444,000	313,799,000
Amortization of Intangible Assets	22,000,000.0	25,000,000.0	$ 27,200,000
Amortization of above market lease, charge to rental income	703,000	$ 777,000	$ 913,000
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	18,989,000
Finite-Lived Intangible Assets, Amortization Expense, Year Two	16,063,000
Finite-Lived Intangible Assets, Amortization Expense, Year Three	13,192,000
Finite-Lived Intangible Assets, Amortization Expense, Year Four	11,246,000
Finite-Lived Intangible Assets, Amortization Expense, Year Five	8,690,000
Finite-Lived Intangible Assets, Amortization Expense, after Year Five	26,630,000
Finite-Lived Intangible Assets, Net	94,810,000
Net Charge to Rental Income Year One	639,000
Net Charge to Rental Income Year Two	367,000
Net Charge to Rental Income Third Year	353,000
Net Charge to Rental Income Year Four	353,000
Net Charge to Rental Income Year Five	59,000
Net Charge to Rental Income After Year Five	0
Net Charge to Rental Income	$ 1,771,000