CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Thousands, $ in Thousands	Total Stockholders' Equity	Common Stock	Additional Paid-In Capital	Cumulative Dividends In Excess Of Earnings	Accumulated Other Comprehensive Loss	Noncontrolling Interests	Total
Balance at Dec. 31, 2013	$ 10,723,300	$ 456,961	$ 11,334,041	$ (1,053,215)	$ (14,487)	$ 207,834	$ 10,931,134
Balance (in shares) at Dec. 31, 2013		456,961
Increase (Decrease) in Stockholders' Equity
Net income (loss)	477,996			477,996		7,906	485,902
Other comprehensive income (losses)	2,818				2,818		2,818
Issuance of common stock, net	53,682	$ 1,954	51,728			(73)	53,609
Issuance of common stock, net (in shares)		1,954
Repurchase of common stock	(11,086)	$ (284)	(10,802)				(11,086)
Repurchase of common stock (in shares)		(284)
Exercise of stock options	2,792	$ 111	2,681				2,792
Exercise of stock options (in shares)		111
Amortization of deferred compensation	11,006		11,006				11,006
Common dividends ($1.13 and $1.09 per share for the six months ended June 30, 2015 and 2014, respectively)	(500,364)			(500,364)			(500,364)
Distributions to noncontrolling interests						(7,967)	(7,967)
Issuance of noncontrolling interests						6,434	6,434
Purchase of noncontrolling interests	(13)		(13)			(1,671)	(1,684)
Balance at Jun. 30, 2014	10,760,131	$ 458,742	11,388,641	(1,075,583)	(11,669)	212,463	10,972,594
Balance (in shares) at Jun. 30, 2014		458,742
Balance at Dec. 31, 2014	10,735,297	$ 459,746	11,431,987	(1,132,541)	(23,895)	261,802	10,997,099
Balance (in shares) at Dec. 31, 2014		459,746
Increase (Decrease) in Stockholders' Equity
Net income (loss)	(75,729)			(75,729)		5,974	(69,755)
Other comprehensive income (losses)	(8,220)				(8,220)		(8,220)
Issuance of common stock, net	68,141	$ 2,094	66,047			(2,448)	65,693
Issuance of common stock, net (in shares)		2,094
Repurchase of common stock	(7,690)	$ (171)	(7,519)				(7,690)
Repurchase of common stock (in shares)		(171)
Exercise of stock options	27,425	$ 817	26,608				27,425
Exercise of stock options (in shares)		817
Amortization of deferred compensation	15,724		15,724				15,724
Common dividends ($1.13 and $1.09 per share for the six months ended June 30, 2015 and 2014, respectively)	(521,898)			(521,898)			(521,898)
Distributions to noncontrolling interests	(263)		(263)			(8,143)	(8,406)
Issuance of noncontrolling interests						37,025	37,025
Balance at Jun. 30, 2015	$ 10,232,787	$ 462,486	$ 11,532,584	$ (1,730,168)	$ (32,115)	$ 294,210	$ 10,526,997
Balance (in shares) at Jun. 30, 2015		462,486