Segment and Related Information - Reconciliation of Operating Income from Segments to Consolidated (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segment operating income	$ 31,203	$ 25,194	$ 59,989	$ 46,666
Amortization of acquired software	(456)	(444)	(912)	(925)
Amortization of customer and trade name intangibles	(1,151)	(1,128)	(2,303)	(2,257)
Other income (expense), net	185	(216)	366	(475)
Income before income taxes	29,781	23,406	57,140	43,009
Segment Reconciling Items [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Amortization of acquired software	(456)	(444)	(912)	(925)
Amortization of customer and trade name intangibles	(1,151)	(1,128)	(2,303)	(2,257)
Other income (expense), net	$ 185	$ (216)	$ 366	$ (475)