Consolidated Statements Of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Preferred Stock [Member]	Additional Paid-In Capital [Member]	Dividends In Excess Of Earnings [Member]	Treasury Stock, At Cost [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interests [Member]
Equity, value at Dec. 31, 2014	$ 7,902,936	$ 1,531	$ 200,000	$ 6,270,257	$ (762,464)	$ (2,722)	$ (9,304)	$ 2,205,638
Equity, shares at Dec. 31, 2014		153,114,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of operating partnership units to common stock		424,000
Redemption of operating partnership units to common stock	0	$ 5		14,338				(14,343)
Allocated net income for the year	794,791				583,106			211,685
Dividends/distributions declared	(671,041)				(601,594)			(69,447)
Shares issued pursuant to stock purchase plan, shares		6,000
Shares issued pursuant to stock purchase plan, value	780			780
Net activity from stock option and incentive plan, shares		36,000
Net activity from stock option and incentive plan, value	40,265			5,814				34,451
Acquisition of redeemable noncontrolling interest in property partnership	(1,586)			(1,586)
Sale of interests in property partnerships	0			(1,053)				1,053
Contributions from noncontrolling interests in property partnerships	2,705							2,705
Distributions to noncontrolling interests in property partnerships	(170,049)							(170,049)
Dissolution of property partnership	(4,082)							(4,082)
Effective portion of interest rate contracts	(10,302)						(7,061)	(3,241)
Amortization of interest rate contracts	2,510						2,251	259
Reallocation of noncontrolling interest	0			17,137				(17,137)
Equity, value at Dec. 31, 2015	7,886,927	$ 1,536	200,000	6,305,687	(780,952)	(2,722)	(14,114)	2,177,492
Equity, shares at Dec. 31, 2015		153,580,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of operating partnership units to common stock		191,000
Redemption of operating partnership units to common stock	0	$ 2		6,459				(6,461)
Allocated net income for the year	569,977				512,785			57,192
Dividends/distributions declared	(474,614)				(425,527)			(49,087)
Shares issued pursuant to stock purchase plan, shares		6,000
Shares issued pursuant to stock purchase plan, value	730			730
Net activity from stock option and incentive plan, shares		13,000
Net activity from stock option and incentive plan, value	31,910			3,979				27,931
Sale of interests in property partnerships	0			1,195				(1,195)
Contributions from noncontrolling interests in property partnerships	11,951							11,951
Distributions to noncontrolling interests in property partnerships	(51,564)							(51,564)
Effective portion of interest rate contracts	(47,144)						(41,502)	(5,642)
Amortization of interest rate contracts	3,751						3,365	386
Reallocation of noncontrolling interest	0			15,374				(15,374)
Equity, value at Dec. 31, 2016	$ 7,931,924	$ 1,538	200,000	6,333,424	(693,694)	(2,722)	(52,251)	2,145,629
Equity, shares at Dec. 31, 2016	153,790,175	153,790,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of operating partnership units to common stock		495,000
Redemption of operating partnership units to common stock	$ 0	$ 5		16,911				(16,916)
Allocated net income for the year	562,481				462,439			100,042
Dividends/distributions declared	(535,310)				(480,816)			(54,494)
Shares issued pursuant to stock purchase plan, shares		6,000
Shares issued pursuant to stock purchase plan, value	795			795
Net activity from stock option and incentive plan, shares		34,000
Net activity from stock option and incentive plan, value	37,292			3,899				33,393
Cumulative effect of a change in accounting principle	(2,035)				(272)			(1,763)
Contributions from noncontrolling interests in property partnerships	161,585							161,585
Distributions to noncontrolling interests in property partnerships	(54,176)							(54,176)
Effective portion of interest rate contracts	(6,133)						(3,305)	(2,828)
Amortization of interest rate contracts	6,033						5,127	906
Reallocation of noncontrolling interest	0			22,879				(22,879)
Equity, value at Dec. 31, 2017	$ 8,102,456	$ 1,543	$ 200,000	$ 6,377,908	$ (712,343)	$ (2,722)	$ (50,429)	$ 2,288,499
Equity, shares at Dec. 31, 2017	154,325,286	154,325,000