Stock Options and Stock-Based Compensation (Details 2) (USD $)	3 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Mar. 31, 2012	Mar. 31, 2011
Stock options
Options outstanding, beginning, Shares	751,023	813,662
Options outstanding, ending, Average Price	$ 34.59	$ 29.89	$ 34.19	$ 29.26
Options granted, Shares	11,150	15,675
Options granted, Average Price	$ 41.08	$ 49.56
Options exercised, Shares	(65,573)	(28,544)
Options exercised, Average price	$ 25.45	$ 22.85
Options cancelled, Shares	(44,697)	(3,416)
Options cancelled, Average Price	$ 42.93	$ 29.47
Options outstanding, ending, Shares	651,903	797,377