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, 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)
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)
Beginning balance at Mar. 31, 2021	220,402,000	$ 3,000	185,941,000	$ (564,435,000)	598,893,000
Beginning balance, shares at Mar. 31, 2021		54,529,642		(36,653,552)
Stock issued under stock option plan, net of shares repurchased	5,145,000	$ 0	5,145,000	$ 0	0
Stock issued under stock option plan, net of shares repurchased, shares		113,110
Stock-based compensation expense	1,345,000	$ 0	1,345,000	0	0
Purchase of treasury stock	$ (14,196,000)	0	0	$ (14,196,000)	0
Purchase of treasury stock, shares	(118,893)			(118,893)
Net income	$ 16,843,000	0	0	$ 0	16,843,000
Ending balance at Jun. 30, 2021	$ 229,539,000	$ 3,000	$ 192,431,000	$ (578,631,000)	$ 615,736,000
Ending balance, shares at Jun. 30, 2021		54,642,752		(36,772,445)