Condensed Consolidated Statements of Equity - USD ($) shares in Thousands, $ in Thousands	Total	Preferred stock	Preferred stock 7.00% Series A cumulative redeemable preferred stock	Common stock Class A common stock	Additional paid-in capital	Accumulated distributions in excess of earnings	Accumulated other comprehensive income	Total shareholders' equity
Balance at Dec. 31, 2016			$ 5	$ 237	$ 4,927,155	$ (2,776,033)	$ 722	$ 2,152,086
Balance (in shares) at Dec. 31, 2016			5,400	236,770
Increase (decrease) in shareholders' equity
Net income	$ 105,663					105,663		105,663
Other comprehensive income							487	487
Distributions declared to preferred shareholders						(4,725)		(4,725)
Distributions declared to common shareholders						(77,553)		(77,553)
Issuance of restricted shares (in shares)				285
Stock-based compensation expense, net of forfeitures					3,549			3,549
Shares withheld for employee taxes					(1,333)			(1,333)
Shares withheld for employee taxes (in shares)				(88)
Balance at Jun. 30, 2017			$ 5	$ 231	4,853,680	(2,752,648)	1,209	2,102,477
Balance (in shares) at Jun. 30, 2017			5,400	230,943
Increase (decrease) in shareholders' equity
Cumulative effect of accounting change						(12)	12
Balance at Dec. 31, 2017	1,885,700	$ 0		$ 219	4,574,428	(2,690,021)	1,074	1,885,700
Balance (in shares) at Dec. 31, 2017		0		219,237
Increase (decrease) in shareholders' equity
Net income	52,662					52,662		52,662
Other comprehensive income							3,613	3,613
Distributions declared to common shareholders						(72,710)		(72,710)
Issuance of common stock (in shares)				59
Issuance of restricted shares (in shares)				382
Stock-based compensation expense, net of forfeitures					3,729			3,729
Stock-based compensation expense, net of forfeitures (in shares)				(12)
Shares withheld for employee taxes					(1,405)			(1,405)
Shares withheld for employee taxes (in shares)				(116)
Balance at Jun. 30, 2018	$ 1,871,589	$ 0		$ 219	$ 4,576,752	$ (2,710,081)	$ 4,699	$ 1,871,589
Balance (in shares) at Jun. 30, 2018		0		219,550