Income Taxes - Reconciliation of the Company's Effective Income Tax Rate to the Federal Statutory Rate (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]
Federal income tax at the statutory rate	$ 9,812	$ 7,914	$ (3,370)
State income taxes, net of federal benefit	1,283	969	(357)
Permanent differences	(96)	156	231
Research and development	(386)	(327)	(230)
Return to provision adjustment	(361)	(270)	(458)
Change in liability for unrecognized tax benefits	219	921	(299)
Incentive stock option detriment/(benefit)	(538)	174	449
Change in valuation allowance		(1,429)	1,429
Other	(143)	(234)	16
Provision (benefit) for income taxes	$ 9,790	$ 7,874	$ (2,589)
Effective tax rate	34.90%	34.80%	26.90%