Consolidated Statements Of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total		Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning balance at Dec. 31, 2016	$ 535,637		$ 8,934	$ 336,756	$ 218,947	$ (29,000)
Beginning balance (in shares) at Dec. 31, 2016			29,785
Adoption of new accounting principles	994				994
Net loss	(84,455)				(84,455)
Foreign currency translation adjustment, net of tax	7,688					7,688
Foreign currency hedge, net of tax	(1,114)					(1,114)
Defined benefit pension plans, net of tax	2,630					2,630
Issuance of convertible debt, net of tax	8,415			8,415
Non-cash compensation	7,876			7,876
Vesting of stock awards (in shares)			152
Vesting of stock awards	(947)		$ 45	(992)
Exercise of stock options (in shares)			16
Exercise of stock options	450		$ 5	445
Ending balance at Dec. 31, 2017	477,174		$ 8,984	352,500	135,486	(19,796)
Ending balance (in shares) at Dec. 31, 2017			29,953
Adoption of new accounting principles	6,780				9,110	(2,330)
Net loss	(63,146)	[1]			(63,146)
Foreign currency translation adjustment, net of tax	(12,164)					(12,164)
Foreign currency hedge, net of tax	496					496
Defined benefit pension plans, net of tax	(598)					(598)
Reclassification of convertible debt embedded derivative, net of tax	37,698			37,698
Non-cash compensation	12,256			12,256
Vesting of stock awards (in shares)			231
Vesting of stock awards	(1,396)		$ 69	(1,465)
Ending balance at Dec. 31, 2018	457,100		$ 9,053	400,989	81,450	(34,392)
Ending balance (in shares) at Dec. 31, 2018			30,184
Adoption of new accounting principles	(360)				(360)
Net loss	(32,417)				(32,417)
Foreign currency translation adjustment, net of tax	4,258					4,258
Foreign currency hedge, net of tax	213					213
Defined benefit pension plans, net of tax	(269)					(269)
Non-cash compensation	10,055			10,055
Vesting of stock awards (in shares)			335
Vesting of stock awards	(1,910)		$ 100	(2,010)
Ending balance at Dec. 31, 2019	$ 436,670		$ 9,153	$ 409,034	$ 48,673	$ (30,190)
Ending balance (in shares) at Dec. 31, 2019			30,519

[1] Income (loss) from continuing operations, net income (loss) and the related earnings (loss) per share amounts for each of the quarters in 2018 are revised from those originally reported to correct errors in income tax expense (benefit) associated with the measurement of valuation allowances on deferred tax assets. Based on an analysis of quantitative and qualitative factors, the Company determined the related impacts were not material to its previously filed interim consolidated financial statements, and therefore, amendments of previously filed reports are not required.