Mortgage Notes Payable, Unsecured Notes and Credit Facility (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Apr. 30, 2019	Dec. 31, 2018
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Total mortgage notes payable and unsecured notes and Term Loans	$ 7,355,371		$ 7,102,355
Variable rate unsecured credit facility	0		0
Total mortgage notes payable, unsecured notes, Term Loans and Credit Facility	7,355,371		7,102,355
Unsecured notes
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Fixed rate notes	5,850,000		5,400,000
Variable rate notes	300,000		300,000
Total mortgage notes payable and unsecured notes and Term Loans	6,400,000
Amount of debt discount	8,610		9,879
Deferred financing costs, net	32,742		34,128
Term loan
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Variable rate notes	250,000		250,000
Secured notes
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Fixed rate notes	479,221		533,215
Variable rate notes	476,150		619,140
Total mortgage notes payable and unsecured notes and Term Loans	642,507
Amount of debt discount	14,464		14,590
Deferred financing costs, net	$ 3,265		$ 3,495
Notes Payable Maturities 2019 [Member]
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Stated interest rate (as a percent)	3.38%	2.99%