Income Taxes Unrecognized tax benefits (Details) (USD $)	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits Beginning Balance	$ 152,845,000	$ 70,490,000	$ 58,125,000
Unrecognized Tax Benefits Increases Related To Acquisitions	341,000	45,624,000	0
Unrecognized Tax Benefits, Decrease Related to Settlements with Tax Authorities	(15,016,000)	0	0
Unrecognized Tax Benefits, Decreases Related to Statute of Limitation Expiration	(4,069,000)	(5,751,000)	(2,153,000)
Unrecognized Tax Benefits, Increases Related to Current Year Tax Positions	14,669,000	42,328,000	11,992,000
Unrecognized Tax Benefits, Increases Related to Prior Year Tax Positions	1,108,000	154,000	2,526,000
Unrecognized Tax Benefits Ending Balance	149,878,000	152,845,000	70,490,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued [Abstract]
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	300,000	3,200,000
Unrecognized Tax Benefits, Income Tax Penalties Accrued	29,700,000	30,600,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	$ 200,000	$ 800,000	$ 900,000