Stock Based Compensation and Stock Options (Details 2) (USD $)	3 Months Ended		6 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Stock options
Options outstanding, beginning, Shares	651,903	797,377	751,323	813,622
Options outstanding, beginning, Weighted Average Exercise Per Share	$ 34.59	$ 29.87	$ 34.19	$ 29.26
Options granted, Shares	20,550	29,550	31,700	45,225
Options granted, Average Price	$ 44.14	$ 43.73	$ 43.06	$ 45.75
Options exercised, Shares	(36,106)	(26,429)	(101,679)	(54,973)
Options exercised, Average Price	$ 24.55	$ 23.51	$ 25.13	$ 23.17
Options cancelled,Shares	(4,082)	(1,625)	(49,079)	(5,001)
Options cancelled, Average Price	$ 45.05	$ 25.31	$ 43.08	$ 28.20
Options outstanding, ending, Shares	632,265	798,873	632,265	798,873
Options outstanding, ending, Weighted Average Exercise Per Share	$ 35.41	$ 30.62	$ 35.41	$ 30.62