Income Taxes - Reconciliation of the Company's Effective Income Tax Rate to the Federal Statutory Rate (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Federal income tax at the statutory rate	$ 12,347	$ 11,236	$ 9,812
State income taxes, net of federal benefit	1,061	1,433	1,283
Difference between statutory and foreign tax rates	2,442	0	0
Permanent differences	(205)	98	(96)
Research and development	(1,050)	(452)	(386)
Return to provision adjustment	(67)	28	(361)
Change in liability for unrecognized tax benefits	(156)	202	219
Incentive stock option benefit	(144)	(616)	(538)
Change in valuation allowance	1,200	500	0
Other	0	(36)	(143)
Provision for income taxes	$ 15,428	$ 12,393	$ 9,790
Effective tax rate	43.60%	38.40%	34.90%