Income Tax - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Contingency [Line Items]
Deferred tax assets, valuation allowance	$ 0
Unrecognized tax benefits	0	$ 0
Income taxes, net of refunds	$ 30,200,000	$ 27,300,000	$ 10,200,000
State
Income Tax Contingency [Line Items]
Income tax examination, year under examination	2012