Mortgage Notes Payable, Unsecured Notes and Credit Facility (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Notes Payable, Unsecured Notes and Credit Facility
Total mortgage notes payable, unsecured notes and Term Loans	$ 7,100,685,000	$ 7,102,355,000
Credit Facility	0	0
Total mortgage notes payable, unsecured notes, Term Loans and Credit Facility	7,100,685,000	7,102,355,000
Unsecured notes
Notes Payable, Unsecured Notes and Credit Facility
Fixed rate notes	5,400,000,000	5,400,000,000
Variable rate notes	300,000,000	300,000,000
Total mortgage notes payable, unsecured notes and Term Loans	5,950,000,000
Amount of debt discount	9,515,000	9,879,000
Amount of deferred financing costs, net	33,158,000	34,128,000
Term Loans
Notes Payable, Unsecured Notes and Credit Facility
Variable rate notes	250,000,000	250,000,000
Secured notes
Notes Payable, Unsecured Notes and Credit Facility
Fixed rate notes	531,771,000	533,215,000
Variable rate notes	618,914,000	619,140,000
Total mortgage notes payable, unsecured notes and Term Loans	1,096,560,000
Amount of debt discount	14,559,000	14,590,000
Amount of deferred financing costs, net	3,386,000	3,495,000
Line of Credit [Member]
Notes Payable, Unsecured Notes and Credit Facility
Credit Facility	$ 0	$ 0