Stock Options and Stock-Based Compensation (Details 4) (USD $)	3 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Stock Options and Stock-Based Compensation [Abstract]
Options outstanding, beginning, Shares	751,023	813,662
Options outstanding, beginning, Weighted Average Exercise Per Share	$ 34.19	$ 29.26	$ 34.59	$ 29.89
Granted, Number of Options	11,150	15,675
Granted, Weighted Average Exercise Per Share	$ 41.08
Options exercised, Shares	(65,573)	(28,544)
Exercised, Weighted Average Exercise Per Share	$ 25.45	$ 22.85
Options cancelled, Shares	(44,697)	(3,416)
Cancelled - forfeited, Weighted Average Exercise Per Share	$ 43.04
Cancelled- expired, Number of Options	(302)
Cancelled- expired, Weighted Average Exercise Per Share	$ 42.93	$ 29.47
Options outstanding, ending, Shares	651,903	797,377
Ending outstanding, Weighted Average Remaining Contractual Life (Years)	3 years 3 months 15 days
Ending outstanding, Aggregate Intrinsic Value	$ 9,689,000
Ending vested and expected to vest, Number of Options	586,470
Ending vested and expected to vest, Weighted Average Exercise Per Share	$ 33.21
Ending vested and expected to vest, Weighted Average Remaining Contractual Life (Years)	3 years 2 months 9 days
Ending vested and expected to vest, Aggregate Intrinsic Value	9,444,000
Ending exercisable, Number of Options	325,797
Ending exercisable, Weighted Average Exercise Per Share	$ 27.27
Ending exercisable, Weighted Average Remaining Contractual Life (Years)	2 years 6 months 29 days
Ending exercisable, Aggregate Intrinsic Value	$ 7,083,000