Annual report pursuant to Section 13 and 15(d)

Common Stock - Summary of Stock Options Outstanding Regarding Number of Common Shares Issuable upon Exercise of Vested Options (Detail)

v3.8.0.1
Common Stock - Summary of Stock Options Outstanding Regarding Number of Common Shares Issuable upon Exercise of Vested Options (Detail)
 12 Months Ended
Dec. 31, 2016
$ / shares
shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Number of Vested Options | shares 62,824
Exercise Price Range, Weighted Average Vested Price $ 91.79
Exercise Price Range, Weighted Average Remaining Contractual Term 5 years 11 months 12 days
Range one [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Number of Vested Options | shares 3,644
Exercise Price Range, Weighted Average Vested Price $ 2.89
Exercise Price Range, Weighted Average Remaining Contractual Term 9 years 6 months 29 days
Exercise Price Range, Lower Range Limit $ 2.89
Exercise Price Range, Upper Range Limit $ 6.95
Range two [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Number of Vested Options | shares 4,090
Exercise Price Range, Weighted Average Vested Price $ 11.00
Exercise Price Range, Weighted Average Remaining Contractual Term 8 years 4 months 24 days
Exercise Price Range, Lower Range Limit $ 6.96
Exercise Price Range, Upper Range Limit $ 15.73
Range three [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Number of Vested Options | shares 14,883
Exercise Price Range, Weighted Average Vested Price $ 20.46
Exercise Price Range, Weighted Average Remaining Contractual Term 7 years 4 months 17 days
Exercise Price Range, Lower Range Limit $ 15.74
Exercise Price Range, Upper Range Limit $ 20.63
Range four [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Number of Vested Options | shares 5,432
Exercise Price Range, Weighted Average Vested Price $ 31.25
Exercise Price Range, Weighted Average Remaining Contractual Term 6 years 9 months 7 days
Exercise Price Range, Lower Range Limit $ 20.64
Exercise Price Range, Upper Range Limit $ 37.35
Range five [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Number of Vested Options | shares 2,451
Exercise Price Range, Weighted Average Vested Price $ 84.08
Exercise Price Range, Weighted Average Remaining Contractual Term 5 years 9 months
Exercise Price Range, Lower Range Limit $ 37.36
Exercise Price Range, Upper Range Limit $ 128.64
Range six [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Number of Vested Options | shares 8,758
Exercise Price Range, Weighted Average Vested Price $ 129.69
Exercise Price Range, Weighted Average Remaining Contractual Term 6 years 2 months 12 days
Exercise Price Range, Lower Range Limit $ 128.65
Exercise Price Range, Upper Range Limit $ 130.57
Range seven [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Number of Vested Options | shares 6,450
Exercise Price Range, Weighted Average Vested Price $ 131.45
Exercise Price Range, Weighted Average Remaining Contractual Term 5 years 2 months 8 days
Exercise Price Range, Lower Range Limit $ 130.58
Exercise Price Range, Upper Range Limit $ 134.81
Range eight [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Number of Vested Options | shares 5,927
Exercise Price Range, Weighted Average Vested Price $ 142.41
Exercise Price Range, Weighted Average Remaining Contractual Term 4 years 4 months 9 days
Exercise Price Range, Lower Range Limit $ 134.82
Exercise Price Range, Upper Range Limit $ 143.88
Range nine [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Number of Vested Options | shares 7,019
Exercise Price Range, Weighted Average Vested Price $ 172.70
Exercise Price Range, Weighted Average Remaining Contractual Term 3 years 4 days
Exercise Price Range, Lower Range Limit $ 143.89
Exercise Price Range, Upper Range Limit $ 185.85
Range ten [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Number of Vested Options | shares 4,170
Exercise Price Range, Weighted Average Vested Price $ 237.60
Exercise Price Range, Weighted Average Remaining Contractual Term 2 years 2 months 16 days
Exercise Price Range, Lower Range Limit $ 185.86
Exercise Price Range, Upper Range Limit $ 245.08