Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Distributions In Excess of Earnings	Treasury Stock	Noncontrolling Interests	Series L Preferred Stock	Series L Preferred Stock Preferred Stock	Series L Preferred Stock Additional Paid-in Capital	Series A Preferred Stock Preferred Stock
Balance (in shares) at Dec. 31, 2014		97,581,598
Balance, at beginning of period at Dec. 31, 2014	$ 1,359,816	$ 98	$ 1,824,381	$ 0	$ (460,623)	$ (4,901)	$ 861
Increase (Decrease) in Stockholders' Equity
Contributions from noncontrolling interests	110						110
Distributions to noncontrolling interests	(45)						(45)
Stock based compensation expense (in shares)		8,000
Stock-based compensation expense	971		971
Common dividends	(85,389)				(85,389)
Reclassification of Series A to permanent equity	0
Treasury stock retirement (107,265 shares)	(4,901)		(4,901)			4,901
Other comprehensive income (loss)	(2,519)			(2,519)
Net income	24,403				24,392		11
Balance (in shares) at Dec. 31, 2015		97,589,598
Balance, at end of period at Dec. 31, 2015	1,297,347	$ 98	1,820,451	(2,519)	(521,620)	0	937
Increase (Decrease) in Stockholders' Equity
Distributions to noncontrolling interests	(43)						(43)
Stock based compensation expense (in shares)		10,176
Stock-based compensation expense	164		164
Issuance of shares pursuant to employment agreements (in shares)		76,423
Share repurchases (in shares)		(13,628,116)
Share repurchases	(290,134)	$ (14)	(254,547)		(35,573)
Common dividends	(77,316)				(77,316)
Issuance of Series A Preferred Warrants	5		5
Dividends to holders of Series A Preferred Stock ($1.375 per share)	(9)				(9)
Reclassification of Series A to permanent equity	0
Treasury stock retirement (107,265 shares)	0
Other comprehensive income (loss)	2,010			2,010
Net income	34,565				34,547		18
Balance (in shares) at Dec. 31, 2016		84,048,081							0		0
Balance, at end of period at Dec. 31, 2016	966,589	$ 84	1,566,073	(509)	(599,971)	$ 0	912		$ 0		$ 0
Increase (Decrease) in Stockholders' Equity
Distributions to noncontrolling interests	(43)						(43)
Stock based compensation expense (in shares)		9,585
Stock-based compensation expense	154		154
Share repurchases (in shares)		(40,272,727)
Share repurchases	(886,010)	$ (40)	(752,218)		(133,752)
Special cash dividends declared to certain common stockholders ($2.990 per share)	(6,447)				(6,447)
Common dividends	(38,327)				(38,327)
Issuance of Series A Preferred Warrants	126		126
Issuance of Series L Preferred Stock (in shares)									8,080,740
Issuance of Series L Preferred Stock								$ 207,845	$ 229,251	$ (21,406)
Dividends to holders of Series A Preferred Stock ($1.375 per share)	(490)				(490)
Reclassification of Series A to permanent equity (in shares)											61,013
Reclassification of Series A to permanent equity	1,417		(101)								$ 1,518
Treasury stock retirement (107,265 shares)	0
Redemption of Series A Preferred Stock (in shares)											(421)
Redemption of Series A Preferred Stock	(7)		3								$ (10)
Other comprehensive income (loss)	2,140			2,140
Net income	379,758				379,737		21
Balance (in shares) at Dec. 31, 2017		43,784,939							8,080,740		60,592
Balance, at end of period at Dec. 31, 2017	$ 626,705	$ 44	$ 792,631	$ 1,631	$ (399,250)		$ 890		$ 229,251		$ 1,508