Notes Payable, Unsecured Notes and Credit Facility (Details) - USD ($) $ in Thousands		Sep. 30, 2015	Dec. 31, 2014
Notes Payable, Unsecured Notes and Credit Facility
Total notes payable and unsecured notes		$ 6,288,982	$ 6,448,138
Credit Facility		0	0
Total mortgage notes payable, unsecured notes and Credit Facility		6,288,982	6,448,138
Unsecured notes
Notes Payable, Unsecured Notes and Credit Facility
Fixed rate notes	[1]	3,275,000	2,750,000
Total notes payable and unsecured notes		3,575,000
Amount of debt discount		6,902	6,735
Term Loan
Notes Payable, Unsecured Notes and Credit Facility
Variable rate notes		300,000	250,000
Secured notes
Notes Payable, Unsecured Notes and Credit Facility
Fixed rate notes	[2]	1,668,496	2,400,677
Variable rate notes		1,045,486	1,047,461
Total notes payable and unsecured notes		2,633,059
Amount of debt premium		24,647	84,449
Credit Facility
Notes Payable, Unsecured Notes and Credit Facility
Credit Facility		$ 0	$ 0

[1] Balances at September 30, 2015 and December 31, 2014 exclude $6,902 and $6,735 of debt discount, respectively, as reflected in unsecured notes, net on the Company’s Condensed Consolidated Balance Sheets.

[2] Balances at September 30, 2015 and December 31, 2014 exclude $24,647 and $84,449 of debt premium, respectively, as reflected in mortgage notes payable on the Company’s Condensed Consolidated Balance Sheets.