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Financial Instruments - Fair Value Hierarchy - Additional Information (Detail)
12 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Disclosure Of Fair Value Measurement [Abstract]    
Transfers between Level 1, Level 2 or Level 3 of fair value hierarchy, description There were no transfers between Level 1, Level 2 and Level 3 during the year. There were no transfers between Level 1, Level 2 and Level 3 during the year.