CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (USD $) In Thousands, unless otherwise specified	Total Stockholders' Equity	Common Stock	Additional Paid-In Capital	Cumulative Dividends In Excess Of Earnings	Accumulated Other Comprehensive Income (Loss)	Total Noncontrolling Interests	Total
Balance at Dec. 31, 2012	$ 10,551,237	$ 453,191	$ 11,180,066	$ (1,067,367)	$ (14,653)	$ 202,540	$ 10,753,777
Balance (in shares) at Dec. 31, 2012		453,191
Increase (Decrease) in Stockholders' Equity
Net income	677,742			677,742		9,625	687,367
Other comprehensive income	(1,226)				(1,226)		(1,226)
Issuance of common stock, net	80,506	1,859	78,647			(2,997)	77,509
Issuance of common stock, net (in shares)		1,859
Repurchase of common stock	(2,502)	(51)	(2,451)				(2,502)
Repurchase of common stock (in shares)		(51)
Exercise of stock options	17,497	875	16,622				17,497
Exercise of stock options (in shares)		875
Amortization of deferred compensation	33,833		33,833				33,833
Common dividends ($1.635 and $1.575 per share for the period ended September 30, 2014 and 2013, respectively)	(716,869)			(716,869)			(716,869)
Distributions to noncontrolling interests						(11,536)	(11,536)
Issuance of noncontrolling interests						12,387	12,387
Balance at Sep. 30, 2013	10,640,218	455,874	11,306,717	(1,106,494)	(15,879)	210,019	10,850,237
Balance (in shares) at Sep. 30, 2013		455,874
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	725,650			725,650		11,311	736,961
Other comprehensive income	(2,977)				(2,977)		(2,977)
Issuance of common stock, net	69,825	2,351	67,474			(73)	69,752
Issuance of common stock, net (in shares)		2,351
Repurchase of common stock	(11,599)	(297)	(11,302)				(11,599)
Repurchase of common stock (in shares)		(297)
Exercise of stock options	3,307	131	3,176				3,307
Exercise of stock options (in shares)		131
Amortization of deferred compensation	16,467		16,467				16,467
Common dividends ($1.635 and $1.575 per share for the period ended September 30, 2014 and 2013, respectively)	(750,835)			(750,835)			(750,835)
Distributions to noncontrolling interests						(11,706)	(11,706)
Issuance of noncontrolling interests						57,354	57,354
Purchase of noncontrolling interests	(13)		(13)			(1,671)	(1,684)
Balance at Sep. 30, 2014	$ 10,773,125	$ 459,146	$ 11,409,843	$ (1,078,400)	$ (17,464)	$ 263,049	$ 11,036,174
Balance (in shares) at Sep. 30, 2014		459,146