Condensed Consolidated Statement of Equity - 3 months ended Mar. 31, 2017 - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Distributions in Excess of Accumulated Earnings [Member]	AOCI Attributable to Parent [Member]	Noncontrolling Interest [Member]
Balance at period beginning at Dec. 31, 2016	$ 6,292,237	$ 6	$ 7,029,679	$ (805,409)	$ (32,098)	$ 100,059
Balances (in shares) at Dec. 31, 2016		65,528
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	187,551			178,964		8,587
Reversal of unrealized gains upon the sale of marketable securities	(1,605)				(1,552)	(53)
Change in fair value of derivatives and amortization of swap settlements	3,639				3,518	121
Change in fair value of marketable securities, net	179				173	6
Issuance of common stock under:
Stock option and restricted stock plans, net	5,794		5,794
Stock option and restricted stock plans, net (in shares)		41
Sale of common stock, net	(65)		(65)
Equity based compensation costs	1,253		1,110			143
Changes in the redemption value of redeemable noncontrolling interest	(731)		(505)			(226)
Contributions from noncontrolling interest	22,506					22,506
Distributions to noncontrolling interest	(5,926)					(5,926)
Redemptions of noncontrolling interest	(1,070)		(835)			(235)
Redemptions of noncontrolling interest (in shares)		1
Common stock dividends	(114,759)			(114,759)
Balance at period end at Mar. 31, 2017	$ 6,389,003	$ 6	$ 7,035,178	$ (741,204)	$ (29,959)	$ 124,982
Balances (in shares) at Mar. 31, 2017		65,570