Condensed Consolidated Statement of Equity - 6 months ended Jun. 30, 2016 - USD ($) shares in Thousands, $ in Thousands	Total	Series H Preferred Stock [Member]	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, 2015	$ 6,337,023	$ 73,750	$ 6	$ 7,003,317	$ (797,329)	$ (42,011)	$ 99,290
Balances (in shares) at Dec. 31, 2015		2,950	65,379
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	163,731				153,849		9,882
Change in fair value of derivatives and amortization of swap settlements	(1,335)					(1,291)	(44)
Change in fair value of marketable securities, net	305					295	10
Issuance of common stock under:
Stock option and restricted stock plans, net	11,760			11,760
Stock option and restricted stock plans, net (in shares)			89
Sale of common stock, net	(279)			(279)
Equity based compensation costs	3,198			2,001			1,197
Redemption of Series H preferred stock	(73,750)	$ (73,750)		2,541	(2,541)
Redemption of Series H preferred stock (in shares)		(2,950)
Changes in the redemption value of redeemable noncontrolling interest	921			365			556
Distributions to noncontrolling interest	(13,471)						(13,471)
Redemptions of noncontrolling interest	(2,233)			(1,743)			(490)
Redemptions of noncontrolling interest (in shares)			11
Common and preferred stock dividends	(210,794)				(210,794)
Balance at period end at Jun. 30, 2016	$ 6,215,076	$ 0	$ 6	$ 7,017,962	$ (856,815)	$ (43,007)	$ 96,930
Balances (in shares) at Jun. 30, 2016		0	65,479