v3.10.0.1
Share-based Payments - Schedule of Activities in RSUs and RSAs Outstanding and Related Information (Details)
 12 Months Ended
Dec. 31, 2018
USD ($)
shares
Dec. 31, 2017
USD ($)
shares
Dec. 31, 2016
USD ($)
shares
Restricted Stock Units      
Disclosure Of Share Based Payments [Line Items]      
Number of Instruments, Beginning balance | shares 195,937 501,480 627,480
Instruments Granted | shares 14,383 80,920 176,080
Instruments Forfeited | shares (15,991) (85,903) (140,000)
Instruments Released | shares (93,946) (300,560) (162,080)
Number of Instruments, Ending balance | shares 100,383 195,937 501,480
Weighted average grant date fair value, Beginning balance | $ $ 42.46 $ 36.73 $ 32.78
Weighted average grant date fair value, Granted | $ 168.24 59.63 41.85
Weighted average grant date fair value, Forfeited | $ 34.93 37.43 30.38
Weighted average grant date fair value, Released | $ 40.12 38.95 32.53
Weighted average grant date fair value, Ending balance | $ $ 63.87 $ 42.46 $ 36.73
Restricted Stock Awards      
Disclosure Of Share Based Payments [Line Items]      
Number of Instruments, Beginning balance | shares 61,880 0 79,360
Instruments Granted | shares 0 61,880 0
Instruments Forfeited | shares 0 0 0
Instruments Released | shares 0 0 (79,360)
Number of Instruments, Ending balance | shares 61,880 61,880 0
Weighted average grant date fair value, Beginning balance | $ $ 90.65 $ 0 $ 23.90
Weighted average grant date fair value, Granted | $ 0 90.65 0
Weighted average grant date fair value, Forfeited | $ 0 0 0
Weighted average grant date fair value, Released | $ 0 0 23.90
Weighted average grant date fair value, Ending balance | $ $ 90.65 $ 90.65 $ 0