Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 23,457	$ 29,785
Total cash, cash equivalents and marketable securities	33,620	47,745
Cash and money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	23,457	25,278
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		4,507
Fair Value Measurements Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	23,457	29,785
Marketable securities	10,163	17,960
Total cash, cash equivalents and marketable securities	33,620	47,745
Fair Value Measurements Recurring | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		4,507
Marketable securities		17,960
Fair Value Measurements Recurring | PIPE Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liability	2,449	5,097
Fair Value Measurements Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	23,457	25,278
Total cash, cash equivalents and marketable securities	23,457	25,278
Fair Value Measurements Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		4,507
Marketable securities	10,163	17,960
Total cash, cash equivalents and marketable securities	10,163	22,467
Fair Value Measurements Recurring | Level 2 | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents		4,507
Marketable securities		17,960
Fair Value Measurements Recurring | Level 3 | PIPE Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liability	2,449	5,097
Fair Value Measurements Recurring | Cash and money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	23,457	25,278
Fair Value Measurements Recurring | Cash and money market funds | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	23,457	$ 25,278
Fair Value Measurements Recurring | Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	10,163
Fair Value Measurements Recurring | Corporate debt securities | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Marketable securities	$ 10,163