Mortgage Notes Payable, Unsecured Notes and Credit Facility (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Total mortgage notes payable and unsecured notes and Term Loans	$ 7,404,313	$ 7,076,758
Variable rate unsecured credit facility	0	0
Total mortgage notes payable, unsecured notes, Term Loans and Credit Facility	7,404,313	7,076,758
Unsecured notes
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Fixed rate notes	5,350,000	4,200,000
Variable rate notes	300,000	0
Total mortgage notes payable and unsecured notes and Term Loans	5,900,000
Amount of debt discount	10,850	8,930
Deferred financing costs, net	36,386	27,768
Term loan
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Variable rate notes	250,000	300,000
Mortgage notes payable
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Fixed rate notes	593,987	1,668,496
Variable rate notes	910,326	908,262
Total mortgage notes payable and unsecured notes and Term Loans	1,312,009
Amount of debt discount	16,351
Deferred financing costs, net	$ 11,256	11,046
Amount of debt premium		$ (1,866)