Consolidated Statement of Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-In-Capital	Treasury Stock	Accumulated Other Comprehensive Income	Retained Earnings	Noncontrolling Interests	Series I Preferred Stock Preferred Stock
Increase (Decrease) in Stockholders' Equity
Cumulative adjustment upon adoption of ASC 610-20 | Accounting Standards Update 2014-09	$ 570,524						$ 570,524
Beginning Balance at Dec. 31, 2017	6,589,454		$ 939	$ 4,968,338	$ (124,049)	$ 18,604	1,139,329	$ 364,361	$ 221,932
Beginning Balance (in shares) at Dec. 31, 2017			92,803
Adjusted Balance at Dec. 31, 2017	7,159,978		$ 939	4,968,338	(124,049)	18,604	1,709,853	364,361	$ 221,932
Increase (Decrease) in Stockholders' Equity
Net income	105,702						105,504	198
Other comprehensive income	9,969					9,969
Preferred dividends	(3,738)						(3,738)
DRSPP proceeds (in shares)			1
DRSPP proceeds	42			42
Reallocation of noncontrolling interest in the Operating Partnership	3,645						3,645
Deferred compensation plan and stock awards, net (in shares)			(19)
Deferred compensation plan and stock awards, net of forfeitures and tax withholdings	3,102			3,102
Repurchases of common stock (in shares)			(3,654)
Repurchases of common stock	(354,744)		$ (37)	(195,617)			(159,090)
Proceeds from stock options exercised (in shares)			4
Proceeds from stock options exercised	729			729
Contributions to consolidated joint venture interests	157							157
Deconsolidation of partially owned entity	(314,596)							(314,596)
Cash distributions to noncontrolling interests	(276)							(276)
Cash distributions declared ($0.8125 per common share, none of which represented a return of capital for federal income tax purposes)	(72,341)						(72,341)
Ending Balance at Mar. 31, 2018	$ 6,537,629	$ 221,932	$ 902	$ 4,776,594	$ (124,049)	$ 28,573	$ 1,583,833	$ 49,844
Ending Balance (in shares) at Mar. 31, 2018			89,135