Net Loss Per Common Share - Additional Information (Detail) - $ / shares |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
---|---|---|---|
Convertible Notes due 2018 and due 2020 | |||
Earnings Per Share [Line Items] | |||
Debt instrument, convertible, conversion price, per share | $ 94.15 | $ 94.15 | $ 94.15 |