Condensed Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands		Total	Common stock	Paid-in capital in excess of par value	Retained deficit	Accumulated other comprehensive loss
Beginning balance at Dec. 31, 2018		$ 487,181	$ 1,038	$ 455,447	$ 31,494	$ (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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of new accounting principle | Accounting Standards Update 2016-02		1,330			1,330
Beginning balance at Dec. 31, 2019		886,772	2,124	966,762	(73,333)	(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)

[1] Stock-based compensation during the three months ended March 31, 2019 includes stock-based compensation expense recognized during the period of $4.0 million and the vested deferred stock awards of $4.3 million.