Equity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Changes in equity
Beginning Balance			$ 9,046,405
Net income attributable to common stockholders	$ 206,142	$ 241,100	586,610	$ 540,929
Cash flow hedge loss reclassified to earnings	1,342	$ 1,546	4,334	$ 4,557
Change in redemption value of redeemable noncontrolling interest			1,722
Dividends declared to common stockholders			(502,417)
Issuance of common stock, net of withholdings			672,034
Amortization of deferred compensation			20,765
Ending Balance	9,829,453		9,829,453
Common stock
Changes in equity
Beginning Balance			1,320
Issuance of common stock, net of withholdings			49
Ending Balance	1,369		1,369
Additional paid-in capital
Changes in equity
Beginning Balance			9,354,685
Issuance of common stock, net of withholdings			673,302
Amortization of deferred compensation			20,765
Ending Balance	10,048,752		10,048,752
Accumulated earnings less dividends
Changes in equity
Beginning Balance			(267,085)
Net income attributable to common stockholders			586,610
Change in redemption value of redeemable noncontrolling interest			1,722
Dividends declared to common stockholders			(502,417)
Issuance of common stock, net of withholdings			(1,317)
Ending Balance	(182,487)		(182,487)
Accumulated other comprehensive loss
Changes in equity
Beginning Balance			(42,515)
Cash flow hedge loss reclassified to earnings			4,334
Ending Balance	$ (38,181)		$ (38,181)