Fair value measurements - Additional Information (Detail) - Warrants	3 Months Ended
	Mar. 31, 2020
Warrant life
Foreign Currency Fair Value Hedge Derivative [Line Items]
Expected option life	2 years
Expected volatility
Foreign Currency Fair Value Hedge Derivative [Line Items]
Measurment input	0.3679
Risk-free interest rate
Foreign Currency Fair Value Hedge Derivative [Line Items]
Measurment input	0.0023
Minimum | Expected volatility
Foreign Currency Fair Value Hedge Derivative [Line Items]
Measurment input	0.262
Maximum | Expected volatility
Foreign Currency Fair Value Hedge Derivative [Line Items]
Measurment input	0.504