Notes Payable, Unsecured Notes and Credit Facility (Details) - USD ($) $ in Thousands		Jun. 30, 2015	Dec. 31, 2014
Notes Payable, Unsecured Notes and Credit Facility
Total notes payable and unsecured notes		$ 6,433,889	$ 6,448,138
Credit Facility		0	0
Total mortgage notes payable, unsecured notes and Credit Facility		6,433,889	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		7,169	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]	1,812,557	2,400,677
Variable rate notes		1,046,332	1,047,461
Total notes payable and unsecured notes		2,762,017
Amount of debt premium		60,410	84,449
Credit Facility
Notes Payable, Unsecured Notes and Credit Facility
Credit Facility		$ 0	$ 0

[1] Balances at June 30, 2015 and December 31, 2014 exclude $7,169 and $6,735 of debt discount, respectively, as reflected in unsecured notes, net on the Company’s Condensed Consolidated Balance Sheets.

[2] Balances at June 30, 2015 and December 31, 2014 exclude $60,410 and $84,449 of debt premium, respectively, as reflected in mortgage notes payable on the Company’s Condensed Consolidated Balance Sheets.