Significant Accounting Policies Goodwill and Other Intangibles (Details)	12 Months Ended
	Mar. 31, 2012 Y
Supply Contracts [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life, minimum (in years)	3
Useful life, maximum (in years)	5
Production Contract [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life, minimum (in years)	5
Useful life, maximum (in years)	10
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life (in years)	20
Internally Developed Software [Member]
Finite-Lived Intangible Assets [Line Items]
Useful life (in years)	5