Segment and Related Information - Reconciliation of Operating Income from Segments to Consolidated (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segment operating income	$ 45,017	$ 36,862
Amortization of acquired software	(5,410)	(5,459)
Amortization of customer and trade name intangibles	(3,458)	(3,362)
Other expense, net	(190)	(467)
Income before income taxes	35,959	27,574
Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Amortization of acquired software	(5,410)	(5,459)
Amortization of customer and trade name intangibles	(3,458)	(3,362)
Other expense, net	$ (190)	$ (467)