CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Cumulative Preferred Distributions	Common Shares	Cumulative Common Distributions	Additional Paid in Capital	Cumulative Net Income	Cumulative Other Comprehensive Loss	Noncontrolling Interest	Series D Preferred Shares
Balance as of beginning of period (in shares) at Dec. 31, 2017			124,217,616						4,915,196
Balance as of beginning of period at Dec. 31, 2017	$ 3,300,495	$ (685,748)	$ 1,242	$ (3,111,868)	$ 4,380,313	$ 2,596,259	$ (95)	$ 1,129	$ 119,263
Increase (Decrease) in Stockholders' Equity
Net income	257,486					257,396		90
Unrealized gain on derivative instruments	456						456
Unrealized gain on marketable securities	535						535
Repurchase of shares (in shares)			(3,027,557)
Repurchase of shares	(89,910)		$ (30)		(89,880)
Share-based compensation (in shares)			292,614
Share-based compensation	15,677		$ 3		14,686			988
Contributions	1							1
Distributions	(315,229)	(7,988)		(307,127)				(114)
Adjustment for noncontrolling interest					901			(901)
Balance as of end of period (in shares) at Sep. 30, 2018			121,482,673						4,915,196
Balance as of end of period at Sep. 30, 2018	3,169,511	(693,736)	$ 1,215	(3,418,995)	4,306,020	2,855,557	(1,006)	1,193	$ 119,263
Balance as of beginning of period (in shares) at Jun. 30, 2018			121,482,673						4,915,196
Balance as of beginning of period at Jun. 30, 2018	3,442,309	(689,742)	$ 1,215	(3,111,868)	4,300,822	2,822,793	(1,469)	1,295	$ 119,263
Increase (Decrease) in Stockholders' Equity
Net income	32,777					32,764		13
Unrealized gain on derivative instruments	0
Unrealized gain on marketable securities	463						463
Share-based compensation	5,197				4,864			333
Distributions	(311,235)	(3,994)		(307,127)				(114)
Adjustment for noncontrolling interest					334			(334)
Balance as of end of period (in shares) at Sep. 30, 2018			121,482,673						4,915,196
Balance as of end of period at Sep. 30, 2018	3,169,511	(693,736)	$ 1,215	(3,418,995)	4,306,020	2,855,557	(1,006)	1,193	$ 119,263
Balance as of beginning of period (in shares) at Dec. 31, 2018			121,572,155						4,915,196
Balance as of beginning of period at Dec. 31, 2018	3,183,998	(693,736)	$ 1,216	(3,420,548)	4,305,974	2,870,974	(342)	1,197	$ 119,263
Increase (Decrease) in Stockholders' Equity
Net income	476,870					476,690		180
Unrealized gain on marketable securities	342						$ 342
Repurchase of shares (in shares)			(168,327)
Repurchase of shares	(5,487)		$ (2)		(5,485)
Share-based compensation (in shares)			520,371
Share-based compensation	11,056		$ 5		10,056			995
Distributions	(438,666)	(5,991)		(431,399)				(1,276)
Adjustment for noncontrolling interest					(192)			192
Balance as of end of period (in shares) at Sep. 30, 2019			121,924,199						4,915,196
Balance as of end of period at Sep. 30, 2019	3,228,113	(699,727)	$ 1,219	(3,851,947)	4,310,353	3,347,664		1,288	$ 119,263
Balance as of beginning of period (in shares) at Jun. 30, 2019			121,922,120						4,915,196
Balance as of beginning of period at Jun. 30, 2019	3,635,623	(697,730)	$ 1,219	(3,420,406)	4,308,049	3,323,778		1,450	$ 119,263
Increase (Decrease) in Stockholders' Equity
Net income	23,896					23,886		10
Unrealized gain on marketable securities	0
Share-based compensation (in shares)			2,079
Share-based compensation	3,408				3,078			330
Distributions	(434,814)	(1,997)		(431,541)				(1,276)
Adjustment for noncontrolling interest					(774)			774
Balance as of end of period (in shares) at Sep. 30, 2019			121,924,199						4,915,196
Balance as of end of period at Sep. 30, 2019	$ 3,228,113	$ (699,727)	$ 1,219	$ (3,851,947)	$ 4,310,353	$ 3,347,664		$ 1,288	$ 119,263