Mortgage Notes Payable, Unsecured Notes and Credit Facility (Details) - USD ($)	Sep. 30, 2020	Feb. 29, 2020	Dec. 31, 2019
Notes Payable, Unsecured Notes and Credit Facility
Total mortgage notes payable and unsecured notes and Term Loans	$ 7,631,099,000		$ 7,355,371,000
Credit Facility	0		0
Total mortgage notes payable, unsecured notes, Term Loans and Credit Facility	7,631,099,000		7,355,371,000
Unsecured notes
Notes Payable, Unsecured Notes and Credit Facility
Long-term Debt, Percentage Bearing Fixed Interest, Amount	6,500,000,000		5,850,000,000
Variable rate notes	0		300,000,000
Total mortgage notes payable and unsecured notes and Term Loans	6,750,000,000
Amount of debt discount	10,782,000		8,610,000
Amount of deferred financing costs, net	38,968,000		32,742,000
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
Long-term Debt, Percentage Bearing Fixed Interest, Amount	409,649,000		479,221,000
Variable rate notes	471,450,000		476,150,000
Total mortgage notes payable and unsecured notes and Term Loans	575,532,000
Amount of debt discount	14,636,000		14,464,000
Amount of deferred financing costs, net	3,067,000		3,265,000
Unsecured Notes 2.30 Percent [Member]
Notes Payable, Unsecured Notes and Credit Facility
Debt Instrument, Face Amount		$ 700,000,000
Line of Credit [Member]
Notes Payable, Unsecured Notes and Credit Facility
Credit Facility	$ 0		$ 0