Consolidated Statements of Stockholders' Equity - Unaudited - USD ($)	Total	Common Stock [Member]	Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]
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	$ 0	3,499,000	$ 0	0
Stock issued under stock option plan, net of shares repurchased, shares		96,183
Stock-based compensation expense	1,225,000	$ 0	1,225,000	0	0
Purchase of treasury stock	(9,119,000)	0	0	$ (9,119,000)	0
Purchase of treasury stock, shares				(124,411)
Net income	13,407,000	0	0	$ 0	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)
Beginning balance at Mar. 31, 2020	189,711,000	$ 3,000	168,935,000	$ (531,764,000)	552,537,000
Beginning balance, shares at Mar. 31, 2020		54,254,557		(36,285,591)
Stock issued under stock option plan, net of shares repurchased	1,482,000	$ 0	1,482,000	$ 0	0
Stock issued under stock option plan, net of shares repurchased, shares		42,255
Stock-based compensation expense	995,000	$ 0	995,000	0	0
Purchase of treasury stock	$ (2,398,000)	0	0	$ (2,398,000)	0
Purchase of treasury stock, shares	(34,638)			(34,638)
Net income	$ 8,302,000	0	0	$ 0	8,302,000
Ending balance at Jun. 30, 2020	$ 198,092,000	$ 3,000	$ 171,412,000	$ (534,162,000)	$ 560,839,000
Ending balance, shares at Jun. 30, 2020		54,296,812		(36,320,229)