Share Based Awards (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Mar. 31, 2012 Y	Mar. 31, 2011 Y	Mar. 31, 2010
Summary of Stock Option Activity
Number of Shares Outstanding Beginning Balance	1,397,556	1,743,926	1,640,164
Weighted Average Exercise Price Outstanding Beginning Balance	$ 22.20	$ 21.58	$ 16.20
Weighted Average Remaining Contractual Life Outstanding Beginning Balance	3.9
Number of Share Granted	459,400	110,000	578,968
Weighted Average Exercise Price Granted	$ 43.04	$ 29.15	$ 29.22
Weighted Average Remaining Contractual Life Granted	7.2
Number of Shares Exercised	(697,157)	(307,428)	(475,206)
Weighted Average Exercise Price Exercised	$ 18.34	$ 18.60	$ 12.32
Weighted Average Remaining Contractual Life Exercised	1.3
Aggregate Intrinsic Value, Exercised	$ 17,698	$ 7,093	$ 8,254
Number of Shares Forfeited/Canceled	(171,462)	(148,942)
Weighted Average Exercise Price Forfeited/Canceled	$ 36.66	$ 27.50
Weighted Average Remaining Contractual Life Forfeited/Canceled	6.4
Number of Shares Outstanding Ending Balance	988,337	1,397,556	1,743,926
Weighted Average Exercise Price Outstanding Ending Balance	$ 32.09	$ 22.20	$ 21.58
Weighted Average Remaining Contractual Life Outstanding Ending Balance	5.4	3.9
Aggregate Intrinsic Value Outstanding Ending Balance	11,499
Number of Shares Vested and expected to vest	953,153
Weighted Average Exercise Price Vested and expected to vest	$ 32.07
Weighted Average Remaining Contractual Life Vested and expected to vest	5.4
Aggregate Intrinsic Value Vested and expected to vest	11,113
Number of Shares Exercisable	210,018
Weighted Average Exercise Price Exercisable	$ 24.88
Weighted Average Remaining Contractual Life Exercisable	3.8
Aggregate Intrinsic Value Exercisable	$ 3,959