Condensed Consolidated Statement of Equity - 6 months ended Jun. 30, 2017 - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Distributions in Excess of Accumulated Earnings [Member]	Accumulated Other Comprehensive Loss, Net [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	263,346			249,723		13,623
Reversal of unrealized gains upon the sale of marketable securities	(1,618)				(1,564)	(54)
Change in fair value of derivatives and amortization of swap settlements	4,817				4,657	160
Change in fair value of marketable securities, net	687				664	23
Issuance of common stock under:
Stock option and restricted stock plans, net	22,041		22,041
Stock option and restricted stock plans, net (in shares)		147
Sale of common stock, net	80,565		80,565
Sale of common stock, net (in shares)		312
Equity based compensation costs	3,361		2,740			621
Changes in the redemption value of redeemable noncontrolling interest	(1,117)		(1,052)			(65)
Contributions from noncontrolling interest	22,506					22,506
Distributions to noncontrolling interest	(15,017)					(15,017)
Redemptions of noncontrolling interest	(3,528)		(2,926)			(602)
Redemptions of noncontrolling interest (in shares)		2
Common stock dividends	(230,253)			(230,253)
Balance at period end at Jun. 30, 2017	$ 6,438,027	$ 6	$ 7,131,047	$ (785,939)	$ (28,341)	$ 121,254
Balances (in shares) at Jun. 30, 2017		65,989