Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in-Capital	Accumulated Other Comprehensive Income (Loss)	Retained Deficit
Beginning Balance (in shares) at Dec. 31, 2018		64,205,604
Beginning Balance at Dec. 31, 2018	$ 108,222	$ 18	$ 234,931	$ (10,740)	$ (115,987)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting changes, net of tax	6,957				6,957
Share-based compensation expense	1,529		1,529
Stock-based plan activity (in shares)		57,106
Stock-based plan activity	(26)		(26)
Comprehensive loss:
Net loss	(25,039)				(25,039)
Change in other postretirement benefit plans, net of tax	373			373
Foreign currency translation adjustment	1,508			1,508
Ending Balance (in shares) at Mar. 31, 2019		64,262,710
Ending Balance at Mar. 31, 2019	$ 93,524	$ 18	236,434	(8,859)	(134,069)
Beginning Balance (in shares) at Dec. 31, 2019	64,741,000	64,740,667
Beginning Balance at Dec. 31, 2019	$ 120,967	$ 19	244,372	(7,063)	(116,361)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	2,864		2,864
Stock-based plan activity (in shares)		336,752
Stock-based plan activity	(194)		(194)
Comprehensive loss:
Net loss	(14,066)				(14,066)
Change in other postretirement benefit plans, net of tax	(681)			(681)
Foreign currency translation adjustment	$ (5,699)			(5,699)
Ending Balance (in shares) at Mar. 31, 2020	65,077,000	65,077,419
Ending Balance at Mar. 31, 2020	$ 103,191	$ 19	$ 247,042	$ (13,443)	$ (130,427)