Income Taxes - Additional Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Income Tax Contingency [Line Items]
Tax at federal statutory rate	35.00%	35.00%	35.00%
Accrued interest and penalties recognized	$ 0.1
2018 | Federal
Income Tax Contingency [Line Items]
Net operating loss carryforwards	1,137.3
2013 | State
Income Tax Contingency [Line Items]
Net operating loss carryforwards	522.5
Research Tax Credit Carryforward | Federal
Income Tax Contingency [Line Items]
Tax credit carryforwards	60.7
Research Tax Credit Carryforward | State
Income Tax Contingency [Line Items]
Tax credit carryforwards	$ 29.4