Property and Equipment - Property and Equipment, Net (Detail) - USD ($)	Mar. 31, 2021	Mar. 31, 2020
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 259,186,000	$ 243,188,000
Less: accumulated depreciation and amortization	(188,567,000)	(167,288,000)
Property and equipment, net	70,619,000	75,900,000
Computer Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	163,829,000	150,780,000
Office Equipment And Computers [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	66,714,000	66,398,000
Land, Building And Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	11,081,000	11,048,000
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 17,562,000	$ 14,962,000