Mortgage Notes Payable, Unsecured Notes and Credit Facility (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Notes Payable, Unsecured Notes and Credit Facility
Total mortgage notes payable, unsecured notes and Term Loans	$ 7,675,879	$ 7,404,313
Credit Facility	0	0
Total mortgage notes payable, unsecured notes, Term Loans and Credit Facility	7,675,879	7,404,313
Unsecured notes
Notes Payable, Unsecured Notes and Credit Facility
Fixed rate notes	5,650,000	5,350,000
Variable rate notes	300,000	300,000
Total mortgage notes payable, unsecured notes and Term Loans	6,200,000
Amount of debt discount	11,039	10,850
Amount of deferred financing costs, net	38,328	36,386
Term Loans
Notes Payable, Unsecured Notes and Credit Facility
Variable rate notes	250,000	250,000
Secured notes
Notes Payable, Unsecured Notes and Credit Facility
Fixed rate notes	566,091	593,987
Variable rate notes	909,788	910,326
Total mortgage notes payable, unsecured notes and Term Loans	1,300,529
Amount of debt discount	16,328	16,351
Amount of deferred financing costs, net	$ 10,729	$ 11,256