Income Taxes Tax credit carryforward (Details) (USD $)	12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Tax Credit Carryforward [Line Items]
Income Tax Holiday, Aggregate Dollar Amount	$ 12,000,000	$ 6,500,000	$ 20,900,000
Income Tax Holiday, Income Tax Benefits Per Share	$ 0.06	$ 0.03	$ 0.10
State and Local Jurisdiction [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Amount	46,500,000
Tax Credit Carryforward, Valuation Allowance	43,500,000
State and Local Jurisdiction [Member] | Minimum [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Expiration Dates	Mar. 31, 2014
State and Local Jurisdiction [Member] | Maximum [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Expiration Dates	Mar. 31, 2028
Foreign Country [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Amount	21,300,000
Tax Credit Carryforward, Valuation Allowance	21,200,000
Foreign Country [Member] | Minimum [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Expiration Dates	Mar. 31, 2014
Foreign Country [Member] | Maximum [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Expiration Dates	Mar. 31, 2023
Research [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Amount	41,900,000
Research [Member] | Minimum [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Expiration Dates	Mar. 31, 2017
Research [Member] | Maximum [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Expiration Dates	Mar. 31, 2033
Alternative Minimum Tax [Member]
Tax Credit Carryforward [Line Items]
Tax Credit Carryforward, Amount	$ 3,000,000