Annual report pursuant to Section 13 and 15(d)

Description of Stock Plans - Calculating Fair Value Options Granted Using the Black-Scholes Option- Pricing Model (Detail)

v3.20.1
Description of Stock Plans - Calculating Fair Value Options Granted Using the Black-Scholes Option- Pricing Model (Detail)
 12 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Mar. 31, 2018
Minimum      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Expected life of the options 5 years 7 days 5 years 6 months 8 days 5 years 7 months 24 days
Maximum      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Expected life of the options 9 years 9 months 29 days 9 years 2 months 10 days 9 years 10 months 2 days
Risk-free interest rate | Minimum      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Stock options, measurement input 0.64% 2.38% 1.77%
Risk-free interest rate | Maximum      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Stock options, measurement input 2.25% 2.96% 2.73%
Expected volatility      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Stock options, measurement input   66.00%  
Expected volatility | Minimum      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Stock options, measurement input 64.00%   66.00%
Expected volatility | Maximum      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Stock options, measurement input 66.00%   73.00%
Expected dividend yield      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Stock options, measurement input 0.00% 0.00% 0.00%
Expected forfeitures      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Stock options, measurement input 29.00% 28.00%  
Expected forfeitures | Minimum      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Stock options, measurement input     28.00%
Expected forfeitures | Maximum      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Stock options, measurement input     29.00%