CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Shares	Additional Paid-in Capital	Cumulative Net Income	Cumulative Other Comprehensive Income (Loss)	Cumulative Distributions	Total Equity Attributable to Common Shareholders	Total Equity Attributable to Noncontrolling Interest
Balance (in shares) at Dec. 31, 2016		237,544,479
Balance at Dec. 31, 2016	$ 3,199,405	$ 2,375	$ 4,533,456	$ 1,618,885	$ 34,549	$ (2,989,860)	$ 3,199,405	$ 0
Increase (Decrease) in Shareholders' Equity
Net (loss) income	151,803			147,610			147,610	4,193
Amounts reclassified from cumulative other comprehensive income to net income	5,082
Other comprehensive income (loss)	52,682				52,682		52,682
Distributions	(370,608)					(370,608)	(370,608)
Share grants (in shares)		103,100
Share grants	2,130	$ 1	2,129				2,130
Share repurchases (in shares)		(17,170)
Share repurchases	(341)		(341)				(341)
Contributions from noncontrolling interest	255,931		74,072				74,072	181,859
Distributions to noncontrolling interest	(13,814)							(13,814)
Balance (in shares) at Dec. 31, 2017		237,630,409
Balance at Dec. 31, 2017	3,277,188	$ 2,376	4,609,316	1,766,495	87,231	(3,360,468)	3,104,950	172,238
Increase (Decrease) in Shareholders' Equity
Adjusted balance at beginning of year	3,277,188	$ 2,376	4,609,316	1,853,924	(198)	(3,360,468)	3,104,950	172,238
Net (loss) income	292,414			286,872			286,872	5,542
Amounts reclassified from cumulative other comprehensive income to net income	0
Other comprehensive income (loss)	(68)				(68)		(68)
Distributions	(370,746)					(370,746)	(370,746)
Share grants (in shares)		123,800
Share grants	2,515	$ 1	2,514				2,515
Share repurchases (in shares)		(24,309)
Share repurchases	(411)		(411)				(411)
Distributions to noncontrolling interest	$ (21,022)							(21,022)
Balance (in shares) at Dec. 31, 2018	237,729,900	237,729,900
Balance at Dec. 31, 2018	$ 3,179,870	$ 2,377	4,611,419	2,140,796	(266)	(3,731,214)	3,023,112	156,758
Increase (Decrease) in Shareholders' Equity
Net (loss) income	(82,878)			(88,234)			(88,234)	5,356
Amounts reclassified from cumulative other comprehensive income to net income	175				175		175
Other comprehensive income (loss)	91				91		91
Distributions	(199,719)					(199,719)	(199,719)
Share grants (in shares)		202,500
Share grants	1,393	$ 2	1,391				1,393
Share repurchases (in shares)		(35,237)
Share repurchases	(299)		(299)				(299)
Distributions to noncontrolling interest	$ (21,583)							(21,583)
Balance (in shares) at Dec. 31, 2019	237,897,163	237,897,163
Balance at Dec. 31, 2019	$ 2,877,050	$ 2,379	$ 4,612,511	$ 2,052,562	$ 0	$ (3,930,933)	$ 2,736,519	$ 140,531