Stock Based Compensation and Stock Options - Stock Options (Detail) - $ / shares	3 Months Ended		6 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Options outstanding, beginning balance	1,167,042	1,118,530	1,163,179	1,115,984
Options granted, Shares	47,300	48,650	87,000	86,050
Options exercised, Shares	(59,804)	(30,957)	(95,641)	(56,950)
Options cancelled, Shares	(18,952)	(150)	(18,952)	(9,011)
Options outstanding, ending balance	1,135,586	1,136,073	1,135,586	1,136,073
Options outstanding, beginning Average Price	$ 28.15	$ 25.60	$ 27.65	$ 24.80
Options granted, Average Price	33.15	40.57	33.85	42.43
Options exercised, Average Price	16.91	18.75	17.75	18.41
Options cancelled, Average Price	36.25	24.24	36.25	29.32
Option outstanding, Weighted Average Exercise per Share, ending balance	$ 28.81	$ 26.42	$ 28.81	$ 26.42