CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common stock	Capital in Excess of Par Value	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Beginning balance (shares) at Dec. 31, 2016		24,858
Beginning balance at Dec. 31, 2016	$ 273,456	$ 249	$ 82,387	$ 325,466	$ (47,950)	$ (86,696)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	49,317			49,317
Other comprehensive income (loss), net of tax	27,802				27,802
Stock repurchased	(2,799)					(2,799)
Stock issued under employee plans (shares)		152
Stock issued under employee plans	1,351	$ 1	1,350
Stock-based compensation expense	3,868		3,868
Stock issued to directors (shares)		8
Stock issued to directors	401		401
Ending balance (shares) at Dec. 31, 2017		25,018
Ending balance at Dec. 31, 2017	353,396	$ 250	88,006	374,783	(20,148)	(89,495)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	34,944			34,944
Other comprehensive income (loss), net of tax	(22,537)				(22,537)
Stock repurchased	(974)					(974)
Stock issued under employee plans (shares)		225
Stock issued under employee plans	855	$ 3	852
Stock-based compensation expense	1,619		1,619
Stock issued to directors (shares)		11
Stock issued to directors	$ 374		374
Ending balance (shares) at Dec. 31, 2018	25,254	25,254
Ending balance at Dec. 31, 2018	$ 369,275	$ 253	90,851	411,325	(42,685)	(90,469)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(70,513)			(70,513)
Other comprehensive income (loss), net of tax	16,706				16,706
Stock repurchased	(154)					(154)
Stock issued under employee plans (shares)		46
Stock issued under employee plans	448		448
Stock-based compensation expense	2,229		2,229
Stock issued to directors (shares)		28
Stock issued to directors	$ 612		612
Ending balance (shares) at Dec. 31, 2019	25,328	25,328
Ending balance at Dec. 31, 2019	$ 318,420	$ 253	$ 94,140	$ 340,629	$ (25,979)	$ (90,623)