Annual report pursuant to Section 13 and 15(d)

Share-Based Compensation - Weighted Average Assumptions Use in Calculation of Fair Value for Service and Performance Conditions SARs Awards Granted (Detail)

v3.19.3.a.u2
Share-Based Compensation - Weighted Average Assumptions Use in Calculation of Fair Value for Service and Performance Conditions SARs Awards Granted (Detail)
12 Months Ended
Dec. 31, 2017
Service condition awards [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Expected volatility 49.20%
Dividend yield 0.00%
Expected term 6 years
Risk-free interest rate 2.20%
Performance condition awards [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Expected volatility 49.60%
Dividend yield 0.00%
Expected term 6 years 1 month 6 days
Risk-free interest rate 2.20%