Stockholders' Equity - Additional Information (Detail) - shares		9 Months Ended
	Aug. 11, 2020	Sep. 30, 2020	Sep. 30, 2019
Equity [Abstract]
Shares of common stock, authorized (in shares)		600,000,000.0
Shares of common stock, issued and sold (in shares)		195,100,000
Stock issued during period, shares, new issues (in shares)		3,300,000	4,100,000
2022 convertible senior notes
Class of Stock [Line Items]
Number of shares to be issued upon exercise of the Warrants (in shares)	2,300,000
2018 Warrants
Class of Stock [Line Items]
Number of shares to be issued upon exercise of the Warrants (in shares)		4,300,000	4,300,000