Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Distributions in Excess of Earnings	Non-controlling Interests	Series A Preferred Stock Preferred Stock	Series L Preferred Stock Preferred Stock
Beginning balance (in shares) at Dec. 31, 2016		84,048,081
Beginning balance at Dec. 31, 2016	$ 966,589	$ 84	$ 1,566,073	$ (509)	$ (599,971)	$ 912
Increase (Decrease) in Stockholders' Equity
Distributions to noncontrolling interests	(37)					(37)
Stock-based compensation expense (in shares)		9,585
Stock-based compensation expense	78		78
Share repurchase (in shares)		(26,181,818)
Share repurchase	(576,000)	$ (26)	(489,027)		(86,947)
Special cash dividends paid to certain common stockholders ($2.26 per share) (Note 11)	(4,872)				(4,872)
Common dividends	(25,620)				(25,620)
Issuance of Series A Preferred Warrants	27		27
Dividends to holders of Series A Preferred Stock	(103)				(103)
Reclassification of Series A Preferred Stock to permanent equity	0
Other comprehensive income	1,112			1,112
Net income	285,307				285,293	14
Ending balance (in shares) at Jun. 30, 2017		57,875,848
Ending balance at Jun. 30, 2017	646,481	$ 58	1,077,151	603	(432,220)	889
Increase (Decrease) in Stockholders' Equity
Net income	91,372
Ending balance (in shares) at Jun. 30, 2017		57,875,848
Ending balance at Jun. 30, 2017	646,481	$ 58	1,077,151	603	(432,220)	889
Beginning balance (in shares) at Dec. 31, 2017		43,784,939					60,592	8,080,740
Beginning balance at Dec. 31, 2017	626,705	$ 44	792,631	1,631	(399,250)	890	$ 1,508	$ 229,251
Increase (Decrease) in Stockholders' Equity
Distributions to noncontrolling interests	(67)					(67)
Stock-based compensation expense (in shares)		10,134
Stock-based compensation expense	86		86
Common dividends	(10,947)				(10,947)
Issuance of Series A Preferred Warrants	40		40
Dividends to holders of Series A Preferred Stock	(1,155)				(1,155)
Reclassification of Series A Preferred Stock to permanent equity (in shares)							246,918
Reclassification of Series A Preferred Stock to permanent equity	5,615		(514)				$ 6,129
Redemption of Series A Preferred Stock	2		2
Other comprehensive income	1,590			1,590
Net income	2,571				2,555	16
Ending balance (in shares) at Jun. 30, 2018		43,795,073					307,510	8,080,740
Ending balance at Jun. 30, 2018	624,440	$ 44	792,245	3,221	(408,797)	839	$ 7,637	$ 229,251
Increase (Decrease) in Stockholders' Equity
Net income	1,949
Ending balance (in shares) at Jun. 30, 2018		43,795,073					307,510	8,080,740
Ending balance at Jun. 30, 2018	$ 624,440	$ 44	$ 792,245	$ 3,221	$ (408,797)	$ 839	$ 7,637	$ 229,251