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 (in shares) at Dec. 31, 2013		24,098
Beginning Balance at Dec. 31, 2013	$ 200,087	$ 2,410	$ 62,284	$ 220,252	$ (8,844)	$ (76,015)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	21,847			21,847
Other comprehensive loss, net of tax	(15,317)				(15,317)
Stock repurchased	(748)					(748)
Stock issued under employee plans (in shares)		524
Stock issued under employee plans	2,457	$ 52	2,405
Excess tax benefit on stock awards	1,486		1,486
Stock-based compensation expense	2,535		2,535
Stock issued to directors (in shares)		9
Stock issued to directors	252	$ 1	251
Ending Balance (in shares) at Dec. 31, 2014		24,631
Ending Balance at Dec. 31, 2014	212,599	$ 2,463	68,961	242,099	(24,161)	(76,763)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	46,259			46,259
Other comprehensive loss, net of tax	(10,424)				(10,424)
Stock repurchased	(8,778)					(8,778)
Stock issued under employee plans (in shares)		91
Stock issued under employee plans	1,698	$ (2)	1,700
Excess tax benefit on stock awards	1,044		1,044
Stock-based compensation expense	2,477		2,477
Stock issued to directors (in shares)		10
Stock issued to directors	350		350
Change in par value	$ 0	$ (2,214)	2,214
Ending Balance (in shares) at Dec. 31, 2015	24,732	24,732
Ending Balance at Dec. 31, 2015	$ 245,225	$ 247	76,746	288,358	(34,585)	(85,541)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Recently adopted accounting standards	47		126	(79)
Net income	37,187			37,187
Other comprehensive loss, net of tax	(13,365)				(13,365)
Stock repurchased	(1,155)					(1,155)
Stock issued under employee plans (in shares)		119
Stock issued under employee plans	1,158	$ 2	1,156
Stock-based compensation expense	4,009		4,009
Stock issued to directors (in shares)		7
Stock issued to directors	$ 350		350
Ending Balance (in shares) at Dec. 31, 2016	24,858	24,858
Ending Balance at Dec. 31, 2016	$ 273,456	$ 249	$ 82,387	$ 325,466	$ (47,950)	$ (86,696)