Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Common Stock in Treasury
Beginning Balance at Mar. 31, 2014	$ 257,216	$ 1,470	$ 52,117	$ 347,469	$ (19)	$ (143,821)
Beginning Balance, shares at Mar. 31, 2014		14,703,084				5,408,246
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	2,038		2,038
Issuance of common stock upon exercise of stock options	46			(760)		$ 806
Issuance of common stock upon exercise of stock options, shares						22,899
Issuance of common stock under equity plan	$ (293)			(1,318)		$ 1,025
Issuance of common stock under equity plan, shares						26,013
Purchase of treasury shares, shares	0
Tax effect of stock awards	$ 268		268
Reduction of deferred tax assets due to expired stock options	(24)		(24)
Cash dividends	(5,878)			(5,878)
Pension and postretirement benefits, net of tax	(72)				(72)
Net income	16,954			16,954
Ending Balance at Mar. 31, 2015	270,255	$ 1,470	54,399	356,467	(91)	$ (141,990)
Ending Balance, shares at Mar. 31, 2015		14,703,084				5,359,334
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	1,654		1,654
Issuance of common stock upon exercise of stock options	770			(895)		$ 1,665
Issuance of common stock upon exercise of stock options, shares						47,560
Issuance of common stock under equity plan	(520)			(2,014)		$ 1,494
Issuance of common stock under equity plan, shares						38,744
Purchase of treasury shares	$ (11,274)					$ (11,274)
Purchase of treasury shares, shares	(397,789)					(397,789)
Tax effect of stock awards	$ 221		221
Reduction of deferred tax assets due to expired stock options	(117)		(117)
Cash dividends	(6,764)			(6,764)
Pension and postretirement benefits, net of tax	29				29
Net income	17,236			17,236
Ending Balance at Mar. 31, 2016	271,490	$ 1,470	56,157	364,030	(62)	$ (150,105)
Ending Balance, shares at Mar. 31, 2016		14,703,084				5,670,819
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense	1,653		1,653
Issuance of common stock upon exercise of stock options	$ 123			(373)		$ 496
Issuance of common stock upon exercise of stock options, shares	34,850					14,177
Issuance of common stock under equity plan	$ (527)			(2,079)		$ 1,552
Issuance of common stock under equity plan, shares						40,323
Purchase of treasury shares, shares	0
Tax effect of stock awards	$ 286		286
Reduction of deferred tax assets due to expired stock options	(99)		(99)
Cash dividends	(7,275)			(7,275)
Pension and postretirement benefits, net of tax	(46)				(46)
Foreign currency translation adjustments	45				45
Net income	28,504			28,504
Ending Balance at Mar. 31, 2017	$ 294,154	$ 1,470	$ 57,997	$ 382,807	$ (63)	$ (148,057)
Ending Balance, shares at Mar. 31, 2017		14,703,084				5,616,319