CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Preferred Shares Series D Preferred Stock	Cumulative Preferred Distributions	Common Shares	Cumulative Common Distributions	Additional Paid in Capital	Cumulative Net Income	Cumulative Other Comprehensive Loss	Noncontrolling Interest
Beginning balance (in shares) at Dec. 31, 2016		4,915,196		123,994,465
Beginning balance at Dec. 31, 2016	$ 3,260,447	$ 119,263	$ (677,760)	$ 1,240	$ (3,111,868)	$ 4,363,177	$ 2,566,603	$ (208)	$ 0
Comprehensive income:
Net income	29,666						29,656		10
Unrealized gain (loss) on derivative instrument	(248)							(248)
Unrealized gain on marketable securities	361							361
Total comprehensive income	29,779
Repurchase of shares (in shares)				(43,329)
Repurchase of shares	(3,188)					(3,188)
Share-based compensation (in shares)				266,480
Share-based compensation	21,414			$ 2		20,156			1,256
Contributions	31								31
Distributions	(7,988)		(7,988)
Adjustment for noncontrolling interest						168			(168)
Ending balance (in shares) at Dec. 31, 2017		4,915,196		124,217,616
Ending balance at Dec. 31, 2017	3,300,495	$ 119,263	(685,748)	$ 1,242	(3,111,868)	4,380,313	2,596,259	(95)	1,129
Comprehensive income:
Net income	272,908						272,813		95
Unrealized gain (loss) on derivative instrument	456							456
Unrealized gain on marketable securities	1,199							1,199
Total comprehensive income	274,563
Repurchase of shares (in shares)				(3,163,730)
Repurchase of shares	(93,976)			$ (31)		(93,945)
Share-based compensation (in shares)				518,269
Share-based compensation	19,697			$ 5		18,371			1,321
Contributions	1								1
Distributions	(316,782)		(7,988)		(308,680)				(114)
Adjustment for noncontrolling interest						1,235			(1,235)
Ending balance (in shares) at Dec. 31, 2018		4,915,196		121,572,155
Ending balance at Dec. 31, 2018	3,183,998	$ 119,263	(693,736)	$ 1,216	(3,420,548)	4,305,974	2,870,974	(342)	1,197
Comprehensive income:
Net income	492,866						492,680		186
Unrealized gain on marketable securities	342							342
Total comprehensive income	493,208
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	14,426			$ 5		13,095			1,326
Distributions	(440,273)		(7,988)		(431,118)				(1,167)
Adjustment for noncontrolling interest						247			(247)
Ending balance (in shares) at Dec. 31, 2019		4,915,196		121,924,199
Ending balance at Dec. 31, 2019	$ 3,245,872	$ 119,263	$ (701,724)	$ 1,219	$ (3,851,666)	$ 4,313,831	$ 3,363,654	$ 0	$ 1,295