Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Jan. 31, 2018	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
income tax benefit reflected in additional paid-in-capital				$ 1,004	$ 772
Tax Cuts and Jobs Act of 2017, income tax benefit			$ 2,500
Effective income tax rate			31.30%	39.40%	39.50%
Corporate income tax			35.00%
Tax reduction due to ASU 2016-09 & Tax Act			8.50%
Change in valuation allowance for deferred tax assets related to tax reform act			$ 300
Increase (Decrease) in valuation allowance due to state net operating loss and tax credit carryforwards				$ (100)
State net operating loss carryforwards			28,000
State tax credit carryforwards			1,400
Unrecognized tax benefits that would impact effective tax rate			2,900
Reductions in the liability for unrecognized tax benefits due to expiration of statues of limitation			1,200
Accrued interest expense			200	200
Liability for interest expense			600	400
Liability for penalties			$ 300	300
Earliest Tax Year [Member] | State [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards experiation period			2018
Tax credit carryforwards experiation period			2018
Latest Tax Year [Member] | State [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards experiation period			2037
Tax credit carryforwards experiation period			2028
2013 and 2014 [Member] | Internal Revenue Service [Member]
Income Tax Contingency [Line Items]
Audit settlement, net		$ 500
Scenario, Forecast
Income Tax Contingency [Line Items]
Corporate income tax	21.00%
Non-Qualified Stock Option [Member] | Restricted Stock Awards [Member]
Income Tax Contingency [Line Items]
income tax benefit reflected in additional paid-in-capital				$ 1,100	$ 900
Non-Qualified Stock Option [Member] | Restricted Stock Awards [Member] | Income Tax Expenses [Member]
Income Tax Contingency [Line Items]
income tax benefit reflected in additional paid-in-capital			$ 3,800