Mortgage Notes Payable, Unsecured Notes and Credit Facility (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Total notes payable and unsecured notes	$ 6,481,291	$ 6,448,138
Variable rate unsecured credit facility	0	0
Total mortgage notes payable, unsecured notes and Credit Facility	6,481,291	6,448,138
Unsecured notes
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Fixed rate notes	3,575,000	2,750,000
Total notes payable and unsecured notes	3,875,000
Amount of debt discount	7,601	6,735
Deferred financing costs, net	21,725	17,732
Term loan
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Variable rate notes	300,000	250,000
Mortgage notes payable
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Fixed rate notes	1,561,109	2,400,677
Variable rate notes	1,045,182	1,047,461
Total notes payable and unsecured notes	2,309,478
Deferred financing costs, net	14,703	18,413
Amount of debt premium	19,686	84,449
Variable rate unsecured credit facility
Mortgage Notes Payable, Unsecured Notes and Credit Facility
Variable rate unsecured credit facility	0	$ 0
Deferred financing costs, net	$ 2,148