Property and Equipment - Property and Equipment, Net (Detail) - USD ($)	Mar. 31, 2019	Mar. 31, 2018
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 240,273,000	$ 230,788,000
Less: accumulated depreciation and amortization	(178,293,000)	(161,432,000)
Property and equipment, net	61,980,000	69,356,000
Computer Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	152,885,000	142,754,000
Office Equipment And Computers [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	68,006,000	67,730,000
Land and Building [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	5,843,000	5,843,000
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 13,539,000	$ 14,461,000