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 Outstanding Options (Detail)

v3.8.0.1
Common Stock - Summary of Stock Options Outstanding Regarding Number of Common Shares Issuable upon Exercise of Outstanding 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 Outstanding Options | shares 1,115,647
Exercise Price Range, Weighted Average Exercise Price $ 7.99
Exercise Price Range, Weighted Average Remaining Contractual Life 9 years 4 months 13 days
Range one [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Lower Range Limit $ 2.89
Exercise Price Range, Upper Range Limit $ 6.95
Exercise Price Range, Number of Outstanding Options | shares 1,052,200
Exercise Price Range, Weighted Average Exercise Price $ 2.89
Exercise Price Range, Weighted Average Remaining Contractual Life 9 years 6 months 29 days
Range two [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Lower Range Limit $ 6.96
Exercise Price Range, Upper Range Limit $ 15.73
Exercise Price Range, Number of Outstanding Options | shares 4,090
Exercise Price Range, Weighted Average Exercise Price $ 11.00
Exercise Price Range, Weighted Average Remaining Contractual Life 8 years 4 months 24 days
Range three [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Lower Range Limit $ 15.74
Exercise Price Range, Upper Range Limit $ 20.63
Exercise Price Range, Number of Outstanding Options | shares 17,983
Exercise Price Range, Weighted Average Exercise Price $ 20.46
Exercise Price Range, Weighted Average Remaining Contractual Life 7 years 4 months 17 days
Range four [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Lower Range Limit $ 20.64
Exercise Price Range, Upper Range Limit $ 37.35
Exercise Price Range, Number of Outstanding Options | shares 6,452
Exercise Price Range, Weighted Average Exercise Price $ 31.53
Exercise Price Range, Weighted Average Remaining Contractual Life 6 years 9 months 3 days
Range five [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Lower Range Limit $ 37.36
Exercise Price Range, Upper Range Limit $ 128.64
Exercise Price Range, Number of Outstanding Options | shares 2,451
Exercise Price Range, Weighted Average Exercise Price $ 84.08
Exercise Price Range, Weighted Average Remaining Contractual Life 5 years 9 months
Range six [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Lower Range Limit $ 128.65
Exercise Price Range, Upper Range Limit $ 130.57
Exercise Price Range, Number of Outstanding Options | shares 8,905
Exercise Price Range, Weighted Average Exercise Price $ 129.69
Exercise Price Range, Weighted Average Remaining Contractual Life 6 years 2 months 12 days
Range seven [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Lower Range Limit $ 130.58
Exercise Price Range, Upper Range Limit $ 134.81
Exercise Price Range, Number of Outstanding Options | shares 6,450
Exercise Price Range, Weighted Average Exercise Price $ 131.45
Exercise Price Range, Weighted Average Remaining Contractual Life 5 years 2 months 8 days
Range eight [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Lower Range Limit $ 134.82
Exercise Price Range, Upper Range Limit $ 143.88
Exercise Price Range, Number of Outstanding Options | shares 5,927
Exercise Price Range, Weighted Average Exercise Price $ 142.41
Exercise Price Range, Weighted Average Remaining Contractual Life 4 years 4 months 9 days
Range nine [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Lower Range Limit $ 143.89
Exercise Price Range, Upper Range Limit $ 185.85
Exercise Price Range, Number of Outstanding Options | shares 7,019
Exercise Price Range, Weighted Average Exercise Price $ 172.70
Exercise Price Range, Weighted Average Remaining Contractual Life 3 years 4 days
Range ten [Member]  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Exercise Price Range, Lower Range Limit $ 185.86
Exercise Price Range, Upper Range Limit $ 245.08
Exercise Price Range, Number of Outstanding Options | shares 4,170
Exercise Price Range, Weighted Average Exercise Price $ 237.60
Exercise Price Range, Weighted Average Remaining Contractual Life 2 years 2 months 16 days