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Stock-Based Compensation - Schedule of Weighted Average Assumptions used in Black-Scholes Valuation Model for Stock Options Granted (Detail)
3 Months Ended 6 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Sep. 30, 2013
Sep. 30, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]        
Expected volatility 75.40% 71.90% 75.10% 71.90%
Risk-free interest rate 1.70% 0.80% 1.70% 0.90%
Expected life (years) 5 years 9 months 18 days 5 years 10 months 24 days 5 years 10 months 24 days 5 years 10 months 24 days
Dividend yield 0.00% 0.00% 0.00% 0.00%