Condensed Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands		Total	Cumulative Effect, Period of Adoption, Adjustment	Common stock	Paid-in capital in excess of par value	Retained deficit	Retained deficit Cumulative Effect, Period of Adoption, Adjustment	Accumulated other comprehensive loss
Beginning balance at Dec. 31, 2018		$ 487,181	$ 1,330	$ 1,038	$ 455,447	$ 31,494	$ 1,330	$ (798)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	[1]	8,279		2	8,277
Shares repurchased and retired related to stock-based compensation		(2,861)			(2,861)
Other comprehensive loss		(3,139)						(3,139)
Net loss		(21,806)				(21,806)
Ending balance at Mar. 31, 2019		468,984		1,040	460,863	11,018		(3,937)
Beginning balance at Dec. 31, 2018		487,181	1,330	1,038	455,447	31,494	1,330	(798)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss		(26,787)
Ending balance at Jun. 30, 2019		465,256		1,039	465,995	6,037		(7,815)
Beginning balance at Dec. 31, 2018		487,181	1,330	1,038	455,447	31,494	1,330	(798)
Ending balance at Dec. 31, 2019		$ 886,772	(1,525)	2,124	966,762	(73,333)	(1,525)	(8,781)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Accounting Standards Update [Extensible List]		us-gaap:AccountingStandardsUpdate201613Member
Beginning balance at Mar. 31, 2019		$ 468,984		1,040	460,863	11,018		(3,937)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	[1]	5,637		0	5,637
Shares repurchased and retired related to stock-based compensation		(506)		(1)	(505)
Other comprehensive loss		(3,878)						(3,878)
Net loss		(4,981)				(4,981)
Ending balance at Jun. 30, 2019		465,256		1,039	465,995	6,037		(7,815)
Beginning balance at Dec. 31, 2019		886,772	(1,525)	2,124	966,762	(73,333)	(1,525)	(8,781)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation		6,880		11	6,869
Shares repurchased and retired related to stock-based compensation		(1,151)		(2)	(1,149)
Other comprehensive loss		(1,513)						(1,513)
Net loss		(71,756)				(71,756)
Ending balance at Mar. 31, 2020		817,707		2,133	972,482	(146,614)		(10,294)
Beginning balance at Dec. 31, 2019		886,772	$ (1,525)	2,124	966,762	(73,333)	$ (1,525)	(8,781)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss		(184,244)
Ending balance at Jun. 30, 2020		711,589		2,141	981,204	(259,102)		(12,654)
Beginning balance at Mar. 31, 2020		817,707		2,133	972,482	(146,614)		(10,294)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation		9,523		12	9,511
Shares repurchased and retired related to stock-based compensation		(793)		(4)	(789)
Other comprehensive loss		(2,360)						(2,360)
Net loss		(112,488)
Ending balance at Jun. 30, 2020		$ 711,589		$ 2,141	$ 981,204	$ (259,102)		$ (12,654)

[1] Stock-based compensation during the six months ended June 30, 2019 includes stock-based compensation expense recognized during the period of $9.6 million and the vested deferred stock awards of $4.3 million.