Income Taxes (Details) (USD $)	3 Months Ended		9 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011		Dec. 31, 2010
Income Tax [Line Items]
Effective income tax rate	30.00%	29.00%	41.00%		30.00%
Federal statutory income tax rate	35.00%	35.00%	35.00%		35.00%
Charge recorded to accrue European Commission fines			$ 49,091,000	[1]	$ (7,445,000)	[1]
Italy [Member] | European Commission Fine [Member]
Income Tax [Line Items]
Non-deductible portion of charge for European Commission fine			$ 40,000,000
Italy [Member] | Excluding European Commission Fine [Member]
Income Tax [Line Items]
Effective income tax rate			29.00%

[1] Item is not included in segment operating income, but is included in consolidated operating income.