Leases - Schedule of Supplemental Cash Flow Information Related to Operating Leases (Detail) - USD ($)	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Cash paid for amounts included in the measurement of operating lease liabilities	$ 15,218,000	$ 14,992,000
Operating lease liabilities arising from obtaining ROU assets	59,145,000	110,606,000
Finance lease liabilities arising from obtaining ROU assets	358,000	0
Reductions to ROU assets resulting from reductions to operating lease liabilities	$ 36,145,000	$ 8,354,000