Fair Value - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($) $ / shares shares	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) $ / shares shares	Sep. 30, 2018 USD ($)	Jun. 30, 2019 shares	Dec. 31, 2018 USD ($) $ / shares shares	Apr. 28, 2017 USD ($) $ / shares shares
Fair Value Measurements Disclosure [Line Items]
Transfers of assets between Level 1, Level 2, and Level 3 of the fair value hierarchy | $	$ 0		$ 0			$ 0
Transfers of liabilities between Level 1, Level 2, and Level 3 of the fair value hierarchy | $	0		0			0
Fair value of contingent consideration | $			(9,700,000)	$ 100,000
Warrants to purchase common shares (in units)							24,900,000
Offering price (in dollars per share) | $ / shares							$ 1.00
Change in fair value of warrant liabilities | $	614,000	$ (8,760,000)	3,036,000	$ (24,438,000)
Series A Warrant
Fair Value Measurements Disclosure [Line Items]
Warrants, exercise price (in dollars per share) | $ / shares							$ 1.00
Series A Warrant | Black-Scholes Merton Model
Fair Value Measurements Disclosure [Line Items]
Estimated fair value of warrants | $							$ 2,500,000
Fair value input, share price (in dollars per share) | $ / shares							$ 0.65
Series A Warrant | Black-Scholes Merton Model | Measurement Input, Expected Term
Fair Value Measurements Disclosure [Line Items]
Fair value input, term							1 year
Series A Warrant | Black-Scholes Merton Model | Measurement Input, Risk Free Interest Rate
Fair Value Measurements Disclosure [Line Items]
Fair value input, risk free rate							0.0107
Series A Warrant | Black-Scholes Merton Model | Measurement Input, Expected Dividend Payment
Fair Value Measurements Disclosure [Line Items]
Fair value input, risk free rate							0
Series A Warrant | Black-Scholes Merton Model | Measurement Input, Price Volatility
Fair Value Measurements Disclosure [Line Items]
Fair value input, risk free rate							0.7314
Series B Warrant
Fair Value Measurements Disclosure [Line Items]
Warrants, exercise price (in dollars per share) | $ / shares							$ 1.00
Estimated fair value of warrants | $	$ 1,600,000		$ 1,600,000			$ 4,600,000	$ 6,200,000
Fair value input, share price (in dollars per share) | $ / shares	$ 0.67		$ 0.67			$ 2.26	$ 0.65
Series B Warrant | Measurement Input, Expected Term
Fair Value Measurements Disclosure [Line Items]
Fair value input, term	2 years 7 months 6 days		2 years 7 months 6 days			3 years 3 months 18 days	5 years
Series B Warrant | Measurement Input, Risk Free Interest Rate
Fair Value Measurements Disclosure [Line Items]
Fair value input, risk free rate	0.0156		0.0156			0.0247	0.0181
Series B Warrant | Measurement Input, Price Volatility
Fair Value Measurements Disclosure [Line Items]
Fair value input, risk free rate	0.914		0.914			0.8760	0.7314
Common Stock
Fair Value Measurements Disclosure [Line Items]
Number of common stock or warrants in each unit (in shares)							1
Common Stock | Series A Warrant
Fair Value Measurements Disclosure [Line Items]
Number of common stock or warrants in each unit (in shares)							1
Common Stock | Series B Warrant
Fair Value Measurements Disclosure [Line Items]
Number of common stock or warrants in each unit (in shares)							0.75
Warrants Not Settleable in Cash
Fair Value Measurements Disclosure [Line Items]
Number of warrants, outstanding (in shares)	5,465,763		5,465,763			4,329,437
Warrants Not Settleable in Cash | Series B Warrant
Fair Value Measurements Disclosure [Line Items]
Warrants, exercise price after adjustment (in dollars per share) | $ / shares	$ 0.67
Number of warrants, issued (in shares)	1,336,326
Number of warrants, outstanding (in shares)	4,065,411		4,065,411		2,729,085