Income Taxes - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016 USD ($) Tax_Positions	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Income Tax Contingency [Line Items]
Valuation allowance	$ 4,061,000	$ 4,582,000
Income tax expense (benefit)	$ 34,983,000	$ 28,689,000	$ 25,427,000
Unrecognized tax benefits number of tax matters | Tax_Positions	0
Unrecognized tax benefits related to identified uncertain tax positions	$ 0
Accounting Standards Update 2016-09 [Member]
Income Tax Contingency [Line Items]
Income tax expense (benefit)	$ (1,700,000)
Earliest Tax Year [Member] | Federal Tax Jurisdiction [Member]
Income Tax Contingency [Line Items]
Tax years subject to examination		2013
Latest Tax Year [Member] | Federal Tax Jurisdiction [Member]
Income Tax Contingency [Line Items]
Tax years subject to examination		2016