Income Taxes (Details 4) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Income Taxes
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 62,400	$ 53,500	$ 40,600
Reconciliation of the beginning and ending amount of unrecognized gross tax benefits
Balance, beginning of year	77,653	51,027	43,662
Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions	9,822	1,361	2,830
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions	10,668	34,959	12,664
Reductions for tax positions of prior years	(3,575)	(6,107)	(5,846)
Decreases related to settlements with taxing authorities	(3,185)	(2,667)	(515)
Expiration of statute of limitations	(552)	(920)	(1,768)
Balance, end of year	90,831	77,653	51,027
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	20,500
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	1,300	3,000	2,200
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	$ 10,000	$ 9,000	$ 6,000