Accounts and Taxes Payable and Accrued Liabilities - Accrued Liabilities (Detail) - USD ($)	Sep. 30, 2020	Mar. 31, 2020
Payables And Accruals [Abstract]
Payroll, payroll taxes and employee benefits	$ 35,935,000	$ 26,024,000
Customer deposits	52,570,000	48,991,000
Accrued professional service fees	7,957,000	5,919,000
Self-insurance accruals	3,374,000	3,248,000
Deferred revenue	20,466,000	17,645,000
Operating lease liabilities	12,867,000	13,223,000
Other	2,599,000	2,276,000
Total accrued liabilities	$ 135,768,000	$ 117,326,000