Income Taxes - Reconciliation of U.S. Federal Statutory Tax Rate to Company's Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
U.S. federal statutory rate	35.00%	35.00%	35.00%
State taxes, net of federal benefit	4.20%	4.20%	4.10%
State deferred tax rate change, net of federal benefit	2.00%	(0.40%)	0.10%
Valuation allowance	1.10%
Other	0.60%	0.20%	1.10%
Effective Income Tax Rate	42.90%	39.00%	40.30%