Property and Equipment - Property and Equipment, Net (Detail) - USD ($)	Mar. 31, 2017	Mar. 31, 2016
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 206,780,000	$ 184,004,000
Less: accumulated depreciation and amortization	(143,738,000)	(130,736,000)
Property and equipment, net	63,042,000	53,268,000
Computer Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	130,641,000	114,883,000
Office Equipment And Computers [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	65,246,000	60,061,000
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 10,893,000	$ 9,060,000