Mortgage Notes Payable, Unsecured Notes and Credit Facility (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Notes Payable, Unsecured Notes and Credit Facility
Total notes payable and unsecured notes	$ 6,681,379	$ 6,481,291
Credit Facility	170,000	0
Total mortgage notes payable, unsecured notes and Credit Facility	6,851,379	6,481,291
Unsecured notes
Notes Payable, Unsecured Notes and Credit Facility
Fixed rate notes	3,800,000	3,575,000
Total notes payable and unsecured notes	4,100,000
Amount of debt discount	6,882	7,601
Deferred Finance Costs, Net	22,871	21,725
Term Loan
Notes Payable, Unsecured Notes and Credit Facility
Variable rate notes	300,000	300,000
Secured notes
Notes Payable, Unsecured Notes and Credit Facility
Fixed rate notes	1,672,758	1,561,109
Variable rate notes	908,621	1,045,182
Total notes payable and unsecured notes	2,293,134
Deferred Finance Costs, Net	12,157	14,703
Amount of debt premium	$ 6,501	$ 19,686