Consolidated Stockholders' Equity - Unaudited - USD ($)	Total	Common Stock [Member]	Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]
Beginning balance at Mar. 31, 2018	$ 171,176,000	$ 3,000	$ 143,705,000	$ (430,989,000)	$ 458,457,000
Beginning balance, shares at Mar. 31, 2018		53,793,986		(34,881,079)
Stock issued under stock option plan, net of shares repurchased	1,218,000		1,218,000
Stock issued under stock option plan, net of shares repurchased, shares		45,553
Stock-based compensation expense	1,179,000		1,179,000
Purchase of treasury stock	(3,486,000)			$ (3,486,000)
Purchase of treasury stock, shares				(66,553)
Net income	11,778,000				11,778,000
Ending balance at Jun. 30, 2018	181,865,000	$ 3,000	146,102,000	$ (434,475,000)	470,235,000
Ending balance, shares at Jun. 30, 2018		53,839,539		(34,947,632)
Beginning balance at Mar. 31, 2019	194,805,000	$ 3,000	155,798,000	$ (466,156,000)	505,160,000
Beginning balance, shares at Mar. 31, 2019		54,021,032		(35,463,238)
Stock issued under stock option plan, net of shares repurchased	3,499,000		3,499,000
Stock issued under stock option plan, net of shares repurchased, shares		96,183
Stock-based compensation expense	1,225,000		1,225,000
Purchase of treasury stock	$ (9,119,000)			$ (9,119,000)
Purchase of treasury stock, shares	(124,411)			(124,411)
Net income	$ 13,407,000				13,407,000
Ending balance at Jun. 30, 2019	$ 203,817,000	$ 3,000	$ 160,522,000	$ (475,275,000)	$ 518,567,000
Ending balance, shares at Jun. 30, 2019		54,117,215		(35,587,649)