CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Shares	Cumulative Common Distributions	Additional Paid in Capital	Cumulative Net Income Available for Common Shareholders	Cumulative Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2019		164,563,034
Beginning balance at Dec. 31, 2019	$ 2,505,878	$ 1,646	$ (5,534,942)	$ 4,547,529	$ 3,491,645	$ 0
Increase (Decrease) in Shareholders' Equity
Net income (loss)	(33,650)				(33,650)
Common share grants (in shares)		6,000
Common share grants	590			590
Common share repurchases and forfeitures (in shares)		(2,637)
Common share repurchases and forfeitures	(43)			(43)
Distributions	(90,509)		(90,509)
Ending balance (in shares) at Mar. 31, 2020		164,566,397
Ending balance at Mar. 31, 2020	2,382,266	$ 1,646	(5,625,451)	4,548,076	3,457,995	0
Beginning balance (in shares) at Dec. 31, 2019		164,563,034
Beginning balance at Dec. 31, 2019	2,505,878	$ 1,646	(5,534,942)	4,547,529	3,491,645	0
Increase (Decrease) in Shareholders' Equity
Net income (loss)	(173,641)
Equity interest in investee’s unrealized gains	63
Ending balance (in shares) at Sep. 30, 2020		164,823,833
Ending balance at Sep. 30, 2020	2,242,084	$ 1,648	(5,627,097)	4,549,466	3,318,004	63
Beginning balance (in shares) at Mar. 31, 2020		164,566,397
Beginning balance at Mar. 31, 2020	2,382,266	$ 1,646	(5,625,451)	4,548,076	3,457,995	0
Increase (Decrease) in Shareholders' Equity
Net income (loss)	(37,349)				(37,349)
Common share grants (in shares)		35,000
Common share grants	831			831
Common share repurchases and forfeitures (in shares)		(3,808)
Common share repurchases and forfeitures	(27)			(27)
Ending balance (in shares) at Jun. 30, 2020		164,597,589
Ending balance at Jun. 30, 2020	2,345,721	$ 1,646	(5,625,451)	4,548,880	3,420,646	0
Increase (Decrease) in Shareholders' Equity
Net income (loss)	(102,642)				(102,642)
Equity interest in investee’s unrealized gains	63					63
Common share grants (in shares)		264,400
Common share grants	871	$ 3		868
Common share repurchases and forfeitures (in shares)		(38,156)
Common share repurchases and forfeitures	(283)	$ (1)		(282)
Distributions	(1,646)		(1,646)
Ending balance (in shares) at Sep. 30, 2020		164,823,833
Ending balance at Sep. 30, 2020	2,242,084	$ 1,648	(5,627,097)	4,549,466	3,318,004	63
Beginning balance (in shares) at Dec. 31, 2020		164,823,833
Beginning balance at Dec. 31, 2020	2,102,790	$ 1,648	(5,628,746)	4,550,385	3,180,263	(760)
Increase (Decrease) in Shareholders' Equity
Net income (loss)	(194,990)				(194,990)
Common share grants	380			380
Distributions	(1,648)		(1,648)
Ending balance (in shares) at Mar. 31, 2021		164,823,833
Ending balance at Mar. 31, 2021	1,906,532	$ 1,648	(5,630,394)	4,550,765	2,985,273	(760)
Beginning balance (in shares) at Dec. 31, 2020		164,823,833
Beginning balance at Dec. 31, 2020	2,102,790	$ 1,648	(5,628,746)	4,550,385	3,180,263	(760)
Increase (Decrease) in Shareholders' Equity
Net income (loss)	(345,814)
Equity interest in investee’s unrealized gains	5
Ending balance (in shares) at Sep. 30, 2021		165,092,638
Ending balance at Sep. 30, 2021	1,753,742	$ 1,651	(5,633,690)	4,552,087	2,834,449	(755)
Beginning balance (in shares) at Mar. 31, 2021		164,823,833
Beginning balance at Mar. 31, 2021	1,906,532	$ 1,648	(5,630,394)	4,550,765	2,985,273	(760)
Increase (Decrease) in Shareholders' Equity
Net income (loss)	(91,110)				(91,110)
Common share grants (in shares)		49,000
Common share grants	1,067	$ 1		1,066
Common share repurchases and forfeitures (in shares)		(15,079)
Common share repurchases and forfeitures	(190)			(190)
Distributions	(1,648)		(1,648)
Ending balance (in shares) at Jun. 30, 2021		164,857,754
Ending balance at Jun. 30, 2021	1,814,651	$ 1,649	(5,632,042)	4,551,641	2,894,163	(760)
Increase (Decrease) in Shareholders' Equity
Net income (loss)	(59,714)				(59,714)
Equity interest in investee’s unrealized gains	5					5
Common share grants (in shares)		291,700
Common share grants	1,048	$ 2		1,046
Common share repurchases and forfeitures (in shares)		(56,816)
Common share repurchases and forfeitures	(600)			(600)
Distributions	(1,648)		(1,648)
Ending balance (in shares) at Sep. 30, 2021		165,092,638
Ending balance at Sep. 30, 2021	$ 1,753,742	$ 1,651	$ (5,633,690)	$ 4,552,087	$ 2,834,449	$ (755)