Equity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Class of Stock [Line Items]
Stock Issued During Period, Shares, Share-based Compensation, Forfeited	12
Changes in equity
Beginning Balance	$ 9,840,526
Net income attributable to common stockholders	237,931	$ 208,144
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Parent	(47,757)	(30)
Cash flow hedge loss reclassified to earnings	1,374	$ 1,595
Change in redemption value of redeemable noncontrolling interest	(299)
Dividends declared to common stockholders	(185,168)
Issuance of common stock, net of withholdings	(7,019)
Amortization of deferred compensation	6,944
Ending Balance	9,846,532
Common stock
Changes in equity
Beginning Balance	1,370
Issuance of common stock, net of withholdings	2
Ending Balance	1,372
Additional paid-in capital
Changes in equity
Beginning Balance	10,068,532
Change in redemption value of redeemable noncontrolling interest	0
Issuance of common stock, net of withholdings	(5,747)
Amortization of deferred compensation	6,944
Ending Balance	10,069,729
Accumulated earnings less dividends
Changes in equity
Beginning Balance	(197,989)
Net income attributable to common stockholders	237,931
Change in redemption value of redeemable noncontrolling interest	(299)
Dividends declared to common stockholders	(185,168)
Issuance of common stock, net of withholdings	(1,274)
Ending Balance	(146,799)
Accumulated other comprehensive loss
Changes in equity
Beginning Balance	(31,387)
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax, Portion Attributable to Parent	(47,757)
Cash flow hedge loss reclassified to earnings	1,374
Ending Balance	$ (77,770)