XML 59 R49.htm IDEA: XBRL DOCUMENT v3.10.0.1
Share-Based Compensation - Information for Restricted Stock Units under Equity Incentive Plan (Detail) - Restricted stock units
9 Months Ended
Sep. 30, 2018
$ / shares
shares
Shares  
Nonvested, beginning of period, in shares | shares 637,667
Granted, in shares | shares 193,405
Vested, in shares | shares (213,944)
Forfeited, in shares | shares (37,080)
Nonvested, end of period, in shares | shares 580,048
Weighted Average Grant Date Fair Value  
Nonvested, beginning of period, in usd per share | $ / shares $ 135.86
Granted, in usd per share | $ / shares 302.53
Vested, in usd per share | $ / shares 130.20
Forfeited, in usd per share | $ / shares 170.97
Nonvested, end of period, in usd per share | $ / shares $ 191.28