XML 73 R63.htm IDEA: XBRL DOCUMENT v3.8.0.1
Stockholders' Equity - Summary of Weighted Average Assumptions Used to Estimate Fair Value of Stock Option (Detail) - Stock Options [Member] - $ / shares
3 Months Ended 9 Months Ended
Sep. 30, 2017
[1]
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Expected option term (in years) 0 years 6 years 6 years 6 years
Risk-free interest rate   1.20% 2.00% 1.40%
Expected volatility   50.00% 40.00% 50.00%
Weighted average exercise price   $ 29.59 $ 38.00 $ 25.08
Weighted average fair value at grant date   $ 14.17 $ 15.72 $ 12.09
[1] No stock options were granted during the three months ended September 30, 2017.