Annual report pursuant to Section 13 and 15(d)

Annual report pursuant to Section 13 and 15(d)

Stock Compensation - Weighted Average Assumptions (Detail)

v3.10.0.1
Stock Compensation - Weighted Average Assumptions (Detail) - $ / shares
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free interest rate (as a percent) 2.50% 1.50% 1.10%
Expected volatility (as a percent) 43.00% 49.00% 54.00%
Dividend yield (as a percent) 0.00% 0.00% 0.00%
Weighted average fair value per share at grant date (in dollars per share) $ 2.80 $ 2.26 $ 2.23
Minimum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term (in years) 1 year 7 months 6 days 3 years 1 year
Maximum      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term (in years) 4 years 4 years 6 months 4 years 6 months