Annual report pursuant to Section 13 and 15(d)

Income Taxes - Additional Information (Detail)

v3.8.0.1
Income Taxes - Additional Information (Detail) - USD ($)
 3 Months Ended 12 Months Ended
Dec. 31, 2017
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Income Taxes [Line Items]          
Tax computed at federal rate, percentage     35.00% 35.00% 35.00%
Tax Cuts and Jobs Act of 2017, Incomplete Accounting, Provisional Income Tax Expense $ 11,600,000   $ 11,644,000 $ 0 $ 0
State and Canadian net operating losses (NOLs) 7,800,000   $ 7,800,000 6,400,000  
State and Canadian net operating losses (NOLs), expiration year     2019    
Valuation allowance, deferred tax assets 1,900,000   $ 1,900,000 1,700,000  
Change in valuation allowance, deferred tax assets     170,000 412,000 583,000
Tax benefit from stock-based award activity included in additional paid-in capital       2,711,000 $ 6,173,000
Uncertain tax positions 0   0 0  
Unrecognized tax benefits related interest or penalties     $ 0 $ 0  
Income Tax Examination, Description     The Company is not currently under income tax examination by any taxing authorities.    
Undistributed earnings of foreign subsidiary $ 0   $ 0    
Minimum [Member]          
Income Taxes [Line Items]          
Open tax years subject to tax examinations     2013    
Maximum [Member]          
Income Taxes [Line Items]          
Open tax years subject to tax examinations     2017    
Scenario, Forecast [Member]          
Income Taxes [Line Items]          
Tax computed at federal rate, percentage   21.00%