Statement of Shareholders' Equity - USD ($)	Total	Common Stock [Member]	Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]
Beginning balance at Mar. 31, 2013	$ 111,402,000	$ 3,000	$ 110,924,000	$ (301,301,000)	$ 301,776,000
Beginning balance, shares at Mar. 31, 2013		52,837,262		(31,317,014)
Stock issued under employee stock purchase plan	346,000		346,000
Stock issued under employee stock purchase plan, shares		8,489
Stock issued under stock option plan, net of shares repurchased	3,386,000		3,386,000
Stock issued under stock option plan, net of shares repurchased, shares		281,115
Stock-based compensation expense	2,140,000		2,140,000
Income tax benefits from stock option exercises	2,035,000		2,035,000
Purchase of treasury stock	$ (27,179,000)			$ (27,179,000)
Purchase of treasury stock, shares	(830,460)			(830,460)
Net income	$ 34,392,000				34,392,000
Ending balance at Mar. 31, 2014	126,522,000	$ 3,000	118,831,000	$ (328,480,000)	336,168,000
Ending balance, shares at Mar. 31, 2014		53,126,866		(32,147,474)
Stock issued under employee stock purchase plan	400,000		400,000
Stock issued under employee stock purchase plan, shares		12,299
Stock issued under stock option plan, net of shares repurchased	1,603,000		1,603,000
Stock issued under stock option plan, net of shares repurchased, shares		103,992
Stock-based compensation expense	2,209,000		2,209,000
Income tax benefits from stock option exercises	397,000		397,000
Purchase of treasury stock	$ (31,798,000)			$ (31,798,000)
Purchase of treasury stock, shares	(845,014)			(845,014)
Net income	$ 28,590,000				28,590,000
Ending balance at Mar. 31, 2015	127,923,000	$ 3,000	123,440,000	$ (360,278,000)	364,758,000
Ending balance, shares at Mar. 31, 2015		53,243,157		(32,992,488)
Stock issued under employee stock purchase plan	$ 371,000		371,000
Stock issued under employee stock purchase plan, shares	2,450,271	10,975
Stock issued under stock option plan, net of shares repurchased	$ 3,749,000		3,749,000
Stock issued under stock option plan, net of shares repurchased, shares		194,540
Stock-based compensation expense	2,192,000		2,192,000
Income tax benefits from stock option exercises	713,000		713,000
Purchase of treasury stock	$ (31,525,000)			$ (31,525,000)
Purchase of treasury stock, shares	(893,771)			(893,771)
Net income	$ 28,525,000				28,525,000
Ending balance at Mar. 31, 2016	$ 131,948,000	$ 3,000	$ 130,465,000	$ (391,803,000)	$ 393,283,000
Ending balance, shares at Mar. 31, 2016		53,448,672		(33,886,259)