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	224,709					224,632		77
Unrealized gain on derivative instruments	456						456
Unrealized gain on marketable securities	72						72
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	10,480		$ 3		9,822			655
Contributions	1							1
Distributions	(3,994)	(3,994)
Adjustment for noncontrolling interest					567			(567)
Balance as of end of period (in shares) at Jun. 30, 2018			121,482,673						4,915,196
Balance as of end 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
Balance as of beginning of period (in shares) at Mar. 31, 2018			121,457,073						4,915,196
Balance as of beginning of period at Mar. 31, 2018	3,401,479	(687,745)	$ 1,214	(3,111,868)	4,295,772	2,785,760	(2,106)	1,189	$ 119,263
Increase (Decrease) in Stockholders' Equity
Net income	37,047					37,033		14
Unrealized gain on derivative instruments	339						339
Unrealized gain on marketable securities	298						298
Share-based compensation (in shares)			25,600
Share-based compensation	5,142		$ 1		4,812			329
Contributions	1							1
Distributions	(1,997)	(1,997)
Adjustment for noncontrolling interest					238			(238)
Balance as of end of period (in shares) at Jun. 30, 2018			121,482,673						4,915,196
Balance as of end 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
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	452,974					452,804		170
Unrealized gain on derivative instruments	0
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)			518,292
Share-based compensation	7,648		$ 5		6,978			665
Distributions	(3,852)	(3,994)		142
Adjustment for noncontrolling interest					582			(582)
Balance as of end of period (in shares) at Jun. 30, 2019			121,922,120						4,915,196
Balance as of end 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
Balance as of beginning of period (in shares) at Mar. 31, 2019			121,899,625						4,915,196
Balance as of beginning of period at Mar. 31, 2019	3,391,561	(695,733)	$ 1,219	(3,420,512)	4,304,560	3,081,492		1,272	$ 119,263
Increase (Decrease) in Stockholders' Equity
Net income	242,377					242,286		91
Unrealized gain on derivative instruments	0
Unrealized gain on marketable securities	0
Repurchase of shares (in shares)			(4,414)
Repurchase of shares	(145)				(145)
Share-based compensation (in shares)			26,909
Share-based compensation	3,721				3,393			328
Distributions	(1,891)	(1,997)		106
Adjustment for noncontrolling interest					241			(241)
Balance as of end of period (in shares) at Jun. 30, 2019			121,922,120						4,915,196
Balance as of end 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