Computation of Basic and Diluted Net (Loss) Income Per Common Share (Parenthetical) (Detail) shares in Millions	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Convertible Notes
Net Income Loss Per Common Share
Initial debt conversion price | $ / shares	$ 31.62
Shares that would be issued upon conversion | shares	14.5
Convertible Notes Hedge Warrant
Net Income Loss Per Common Share
Initial debt conversion price | $ / shares	$ 39.68
Shares that would be issued upon conversion | shares	14.5