XML 67 R74.htm IDEA: XBRL DOCUMENT v3.19.3
Equity-Based Compensation - Schedule of Stock Options Valuation Assumptions (Detail) - $ / shares
9 Months Ended 12 Months Ended
Sep. 30, 2019
Dec. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]    
Weighted average grant-date fair value of options $ 17.59 $ 13.67
Risk-free interest rate 2.40% 2.20%
Expected volatility 38.00% 37.00%
Expected life (in years) 5 years 5 years 1 month 6 days