Equity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Changes in equity
Beginning Balance			$ 9,046,405
Net income attributable to common stockholders	$ 172,324	$ 158,086	380,469	$ 299,825
Cash flow hedge loss reclassified to earnings	1,427	$ 1,438	2,992	$ 3,011
Change in redemption value of redeemable noncontrolling interest			1,807
Dividends declared to common stockholders			(331,323)
Issuance of common stock, net of withholdings			95,037
Amortization of deferred compensation			15,098
Ending Balance	9,210,485		9,210,485
Common stock
Changes in equity
Beginning Balance			1,320
Issuance of common stock, net of withholdings			9
Ending Balance	1,329		1,329
Additional paid-in capital
Changes in equity
Beginning Balance			9,354,685
Issuance of common stock, net of withholdings			96,337
Amortization of deferred compensation			15,098
Ending Balance	9,466,120		9,466,120
Accumulated earnings less dividends
Changes in equity
Beginning Balance			(267,085)
Net income attributable to common stockholders			380,469
Change in redemption value of redeemable noncontrolling interest			1,807
Dividends declared to common stockholders			(331,323)
Issuance of common stock, net of withholdings			(1,309)
Ending Balance	(217,441)		(217,441)
Accumulated other comprehensive loss
Changes in equity
Beginning Balance			(42,515)
Cash flow hedge loss reclassified to earnings			2,992
Ending Balance	$ (39,523)		$ (39,523)