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Stockholders' Equity - Fair Value of Employee Stock Options (Detail) - $ / shares
3 Months Ended 6 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]        
Dividend yield 0.00% 0.00% 0.00% 0.00%
Volatility 116.83% 108.39% 116.83% 108.39%
Risk-free interest rate 0.73% 0.27% 0.73% 0.27%
Expected life of options 6 years 6 years 6 years 6 years
Weighted average grant date fair value $ 6.52 $ 6.22 $ 6.52 $ 6.22