Mortgage Notes Payable, Unsecured Notes and Credit Facility (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Total mortgage notes payable and unsecured notes and Term Loans	$ 7,102,355	$ 7,404,313
Variable rate unsecured credit facility	0	0
Total mortgage notes payable, unsecured notes, Term Loans and Credit Facility	7,102,355	7,404,313
Repayment of unsecured debt	258,579	300,000	$ 504,403
Unsecured notes
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Fixed rate notes	5,400,000	5,350,000
Variable rate notes	300,000	300,000
Total mortgage notes payable and unsecured notes and Term Loans	5,950,000
Amount of debt discount	9,879	10,850
Deferred financing costs, net	34,128	36,386
Term loan
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Variable rate notes	250,000	250,000
Mortgage notes payable
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Fixed rate notes	533,215	593,987
Variable rate notes	619,140	910,326
Total mortgage notes payable and unsecured notes and Term Loans	1,097,280
Amount of debt discount	14,590	16,351
Deferred financing costs, net	$ 3,495	$ 11,256