Condensed Consolidated Statements of Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Cumulative effect of accounting change	[1]	Common Shares of Beneficial Interest	Paid-in Capital	Accumulated Deficit and Distributions in Excess of Net Earnings	Accumulated Deficit and Distributions in Excess of Net Earnings Cumulative effect of accounting change	[1]	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Dec. 31, 2018				148,234,959
Beginning balance at Dec. 31, 2018	$ 706,755			$ 1,482	$ 1,356,133	$ (638,345)			$ (12,515)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(4,629)					(4,629)
Other comprehensive income (loss)	(969)								(969)
Distributions on common shares of beneficial interest	(30,235)					(30,235)
Share-based compensation expense	2,625				2,625
Share-based compensation expense (modification of Restricted Stock Units)	3,044				3,044
Common share issuance related to share-based payment plans, net of shares withheld for employee taxes (in shares)				897,849
Common share issuance related to share-based payment plans, net of shares withheld for employee taxes	3,974			$ 9	3,965
Other	(88)					(88)
Ending balance (in shares) at Mar. 31, 2019				149,132,808
Ending balance at Mar. 31, 2019	680,477			$ 1,491	1,365,767	(673,297)			(13,484)
Beginning balance (in shares) at Dec. 31, 2018				148,234,959
Beginning balance at Dec. 31, 2018	706,755			$ 1,482	1,356,133	(638,345)			(12,515)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	27,353
Ending balance (in shares) at Sep. 30, 2019				191,750,746
Ending balance at Sep. 30, 2019	$ 1,838,579			$ 1,918	2,579,318	(718,874)			(23,783)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Distributions declared per common share of beneficial interest (in USD per share)	$ 0.60
Beginning balance (in shares) at Mar. 31, 2019				149,132,808
Beginning balance at Mar. 31, 2019	$ 680,477			$ 1,491	1,365,767	(673,297)			(13,484)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	4,891					4,891
Other comprehensive income (loss)	(3,493)								(3,493)
Distributions on common shares of beneficial interest	(38,764)					(38,764)
Share-based compensation expense	3,171				3,171
Common share issuance related to share-based payment plans, net of shares withheld for employee taxes (in shares)				439,152
Common share issuance related to share-based payment plans, net of shares withheld for employee taxes	2,327			$ 4	2,323
Issuance of common shares (in shares)				42,062,500
Issuance of common shares	1,207,048			$ 421	1,206,627
Ending balance (in shares) at Jun. 30, 2019				191,634,460
Ending balance at Jun. 30, 2019	1,855,657			$ 1,916	2,577,888	(707,170)			(16,977)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	27,091					27,091
Other comprehensive income (loss)	(6,806)								(6,806)
Distributions on common shares of beneficial interest	(38,795)					(38,795)
Share-based compensation expense	3,359				3,359
Common share issuance related to share-based payment plans, net of shares withheld for employee taxes (in shares)				116,286
Common share issuance related to share-based payment plans, net of shares withheld for employee taxes	(1,927)			$ 2	(1,929)
Ending balance (in shares) at Sep. 30, 2019				191,750,746
Ending balance at Sep. 30, 2019	$ 1,838,579			$ 1,918	2,579,318	(718,874)			(23,783)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Distributions declared per common share of beneficial interest (in USD per share)	$ 0.20
Beginning balance (in shares) at Dec. 31, 2019				191,799,909
Beginning balance at Dec. 31, 2019	$ 1,833,018	$ (500)		$ 1,918	2,582,087	(736,861)	$ (500)		(14,126)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	23,511					23,511
Other comprehensive income (loss)	(29,172)								(29,172)
Distributions on common shares of beneficial interest	(42,568)					(42,568)
Share-based compensation expense	4,298				4,298
Common share issuance related to share-based payment plans, net of shares withheld for employee taxes (in shares)				216,056
Common share issuance related to share-based payment plans, net of shares withheld for employee taxes	(1,506)			$ 2	(1,508)
Issuance of common shares (in shares)				8,250,000
Issuance of common shares	233,595			$ 83	233,512
Ending balance (in shares) at Mar. 31, 2020				200,265,965
Ending balance at Mar. 31, 2020	$ 2,020,676			$ 2,003	2,818,389	(756,418)			(43,298)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Beginning balance (in shares) at Dec. 31, 2019				191,799,909
Beginning balance at Dec. 31, 2019	$ 1,833,018	$ (500)		$ 1,918	2,582,087	(736,861)	$ (500)		(14,126)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	68,547
Ending balance (in shares) at Sep. 30, 2020				203,679,575
Ending balance at Sep. 30, 2020	$ 2,108,872			$ 2,037	2,936,762	(797,935)			(31,992)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Distributions declared per common share of beneficial interest (in USD per share)	$ 0.63
Beginning balance (in shares) at Mar. 31, 2020				200,265,965
Beginning balance at Mar. 31, 2020	$ 2,020,676			$ 2,003	2,818,389	(756,418)			(43,298)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	32,662					32,662
Other comprehensive income (loss)	7,255								7,255
Distributions on common shares of beneficial interest	(43,271)					(43,271)
Share-based compensation expense	4,449				4,449
Common share issuance related to share-based payment plans, net of shares withheld for employee taxes (in shares)				255,311
Common share issuance related to share-based payment plans, net of shares withheld for employee taxes	2,202			$ 2	2,200
Issuance of common shares (in shares)				3,094,431
Issuance of common shares	107,033			$ 31	107,002
Ending balance (in shares) at Jun. 30, 2020				203,615,707
Ending balance at Jun. 30, 2020	2,131,006			$ 2,036	2,932,040	(767,027)			(36,043)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	12,374					12,374
Other comprehensive income (loss)	4,051								4,051
Distributions on common shares of beneficial interest	(43,282)					(43,282)
Share-based compensation expense	4,555				4,555
Common share issuance related to share-based payment plans, net of shares withheld for employee taxes (in shares)				63,868
Common share issuance related to share-based payment plans, net of shares withheld for employee taxes	168			$ 1	167
Ending balance (in shares) at Sep. 30, 2020				203,679,575
Ending balance at Sep. 30, 2020	$ 2,108,872			$ 2,037	$ 2,936,762	$ (797,935)			$ (31,992)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Distributions declared per common share of beneficial interest (in USD per share)	$ 0.21

[1] Refer to Note 2 to the Condensed Consolidated Financial Statements for further discussion of the adoption of ASC 326.