Segment and Related Information - Reconciliation of Operating Income from Segments to Consolidated (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total segment operating income	$ 21,472	$ 16,150
Amortization of acquired software	(481)	(549)
Amortization of customer and trade name intangibles	(1,129)	(1,131)
Other expense, net	(259)	(338)
Income before income taxes	19,603	14,132
Segment Reconciling Items [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Amortization of acquired software	(481)	(549)
Amortization of customer and trade name intangibles	(1,129)	(1,131)
Other expense, net	$ (259)	$ (338)