Summary of Significant Accounting Policies - Compensation Expense and Related Tax Benefit for Equity Based Payments (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total compensation expense	$ 14,727	$ 13,107	$ 10,112
Income tax benefit	5,132	4,522	3,489
Cost Of Sales [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total compensation expense	1,061	1,029	882
Selling And Marketing [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total compensation expense	1,792	1,463	1,368
Research And Development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total compensation expense	1,593	1,387	1,282
General And Administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total compensation expense	$ 10,281	$ 9,228	$ 6,580