Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Summary of Stock Option Activity (Detail)

v3.19.1
Stock-Based Compensation - Summary of Stock Option Activity (Detail) - $ / shares
12 Months Ended
Dec. 31, 2016
Dec. 31, 2018
Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]      
Options Outstanding, Beginning Balance   3,883,432 1,930,600
Options Exercisable, Ending Balance   1,278,038 1,244,968
Weghted-Average Exercise Price Per Share, Ending Balance   $ 7.45 $ 5.20
Options Outstanding, Granted   554,243 2,120,347
Options Outstanding, Exercised   (592,342) (68,780)
Options Outstanding, Forfeited or expired   (643,446) (98,735)
Options Outstanding, Ending Balance 1,930,600 3,201,887 3,883,432
Weighted-Average Exercise Price Per Share, Granted   $ 16.69 $ 13.29
Weighted-Average Exercise Price Per Share, Exercised   4.43 3.95
Weighted-Average Exercise Price Per Share, Forfeited or expired   12.52 1.23
Weighted-Average Exercise Price Per Share, Beginning Balance $ 4.45 $ 10.67 $ 9.16