Condensed Consolidated Statement of Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Distributions in Excess of Accumulated Earnings	Accumulated Other Comprehensive Loss, Net	Noncontrolling Interest
Balance at period beginning at Dec. 31, 2018	$ 6,393,844	$ 7	$ 7,093,079	$ (812,796)	$ (13,217)	$ 126,771
Balances (in shares) at Dec. 31, 2018		65,890
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	125,505			118,858		6,647
Reversal of unrealized gains upon the sale of marketable debt securities	33				32	1
Change in fair value of derivatives and amortization of swap settlements	(1,993)				(1,926)	(67)
Change in fair value of marketable debt securities, net	123				119	4
Issuance of common stock under:
Stock option and restricted stock plans, net	3,204		3,204
Stock option and restricted stock plans, net (in shares)		51
Sale of common stock, net	(20)		(20)
Equity based compensation costs	2,600		2,301			299
Retirement of common stock, net	(56,989)	$ 0	(56,989)
Retirement of common stock, net (in shares)		(234)
Changes in the redemption value of redeemable noncontrolling interest	(1,767)		(3,027)			1,260
Distributions to noncontrolling interest	(7,164)					(7,164)
Redemptions of noncontrolling interest	(12,213)		(10,394)			(1,819)
Common stock dividends	(128,149)			(128,149)
Balance at period end at Mar. 31, 2019	6,317,195	$ 7	7,028,154	(822,087)	(14,817)	125,938
Balances (in shares) at Mar. 31, 2019		65,716
Balance at period beginning at Dec. 31, 2019	6,403,504	$ 7	7,121,927	(887,619)	(13,888)	183,077
Balances (in shares) at Dec. 31, 2019		66,092
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	328,765			315,006		13,759
Change in fair value of derivatives and amortization of swap settlements	(8,782)				(8,486)	(296)
Change in fair value of marketable debt securities, net	(305)				(294)	(11)
Issuance of common stock under:
Stock option and restricted stock plans, net	8,665		8,665
Stock option and restricted stock plans, net (in shares)		89
Sale of common stock, net	(70)		(70)
Equity based compensation costs	1,698		1,619			79
Retirement of common stock, net	(176,311)	$ 0	(176,311)
Retirement of common stock, net (in shares)		(776)
Changes in the redemption value of redeemable noncontrolling interest	4,767		4,741			26
Changes in noncontrolling interest from acquisition	1,349					1,349
Distributions to noncontrolling interest	(7,879)					(7,879)
Redemptions of noncontrolling interest	(1,368)		(1,048)			(320)
Redemptions of noncontrolling interest (in shares)		7
Common stock dividends	(135,894)			(135,894)
Balance at period end at Mar. 31, 2020	$ 6,417,949	$ 7	$ 6,959,523	$ (708,697)	$ (22,668)	$ 189,784
Balances (in shares) at Mar. 31, 2020		65,412