Income Taxes Unrecognized tax benefits (Details) (USD $)	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits Beginning Balance	$ 58,125,000	$ 57,140,000	$ 70,051,000
Unrecognized Tax Benefits Increases Related To Acquisitions	0	36,587,000	0
Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions	(2,153,000)	(49,932,000)	(25,492,000)
Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions	11,992,000	13,951,000	11,332,000
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions	2,526,000	379,000	1,249,000
Unrecognized Tax Benefits Ending Balance	70,490,000	58,125,000	57,140,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued [Abstract]
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	3,100,000	2,100,000
Unrecognized Tax Benefits, Income Tax Penalties Accrued	900,000	1,000,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	900,000	(3,600,000)	2,500,000
Scenario, Previously Reported [Member]
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits Ending Balance		$ 45,900,000