Summary of Significant Accounting Policies - Difference Between Federal Statutory Rate and Effective Tax Rate on the Income (Loss) Before Income Taxes Due (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Tax Disclosure [Abstract]
Tax at statutory rate	35.00%	35.00%	35.00%	35.00%
Tax effect of:
Valuation allowance on deferred tax assets	(42.10%)	(22.10%)	(40.10%)	(48.50%)
State income taxes, net of federal benefit	5.00%	(11.80%)	4.30%	4.20%
Other	(0.40%)	0.70%	(1.40%)	(0.30%)
Effective tax rate	(2.50%)	1.80%	(2.20%)	(9.60%)