Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Cumulative effect of accounting changes, net of tax	Common Stock	Additional Paid-in-Capital	Accumulated Other Comprehensive Income (Loss)	Retained Deficit	Retained Deficit Cumulative effect of accounting changes, net of tax
Beginning Balance (in shares) at Dec. 31, 2018			64,205,604
Beginning Balance at Dec. 31, 2018	$ 108,222	$ 6,957	$ 18	$ 234,931	$ (10,740)	$ (115,987)	$ 6,957
Increase (Decrease) in Stockholders' Equity [Roll Forward]
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 income (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, 2018			64,205,604
Beginning Balance at Dec. 31, 2018	108,222	$ 6,957	$ 18	234,931	(10,740)	(115,987)	$ 6,957
Comprehensive loss:
Net income (loss)	(22,085)
Change in other postretirement benefit plans, net of tax	373
Foreign currency translation adjustment	2,828
Ending Balance (in shares) at Jun. 30, 2019			64,298,157
Ending Balance at Jun. 30, 2019	98,842		$ 18	237,478	(7,539)	(131,115)
Beginning Balance (in shares) at Mar. 31, 2019			64,262,710
Beginning Balance at Mar. 31, 2019	93,524		$ 18	236,434	(8,859)	(134,069)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	1,132			1,132
Stock-based plan activity (in shares)			35,447
Stock-based plan activity	(88)			(88)
Comprehensive loss:
Net income (loss)	2,954					2,954
Change in other postretirement benefit plans, net of tax	0
Foreign currency translation adjustment	1,320				1,320
Ending Balance (in shares) at Jun. 30, 2019			64,298,157
Ending Balance at Jun. 30, 2019	$ 98,842		$ 18	237,478	(7,539)	(131,115)
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 income (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			65,077,419
Ending Balance at Mar. 31, 2020	$ 103,191		$ 19	247,042	(13,443)	(130,427)
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)
Comprehensive loss:
Net income (loss)	13,049
Change in other postretirement benefit plans, net of tax	(681)
Foreign currency translation adjustment	$ (3,262)
Ending Balance (in shares) at Jun. 30, 2020	65,211,000		65,210,907
Ending Balance at Jun. 30, 2020	$ 135,396		$ 19	249,695	(11,006)	(103,312)
Beginning Balance (in shares) at Mar. 31, 2020			65,077,419
Beginning Balance at Mar. 31, 2020	103,191		$ 19	247,042	(13,443)	(130,427)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	2,607			2,607
Stock-based plan activity (in shares)			133,488
Stock-based plan activity	46			46
Comprehensive loss:
Net income (loss)	27,115					27,115
Change in other postretirement benefit plans, net of tax	0
Foreign currency translation adjustment	$ 2,437				2,437
Ending Balance (in shares) at Jun. 30, 2020	65,211,000		65,210,907
Ending Balance at Jun. 30, 2020	$ 135,396		$ 19	$ 249,695	$ (11,006)	$ (103,312)