XML 40 R30.htm IDEA: XBRL DOCUMENT v3.7.0.1
Weighted-Average Assumptions for Stock Option Grants using Black-Scholes Option-Pricing Model (Detail) - Stock Options
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Risk-free interest rate 2.00% 1.40%
Expected volatility of common stock 58.10% 60.00%
Dividend yield 0.00% 0.00%
Expected option term 5 years 9 months 18 days 5 years 7 months 6 days