Fair Value Measurement - Schedule of Fair Value Assets And Liabilities Measured On Recurring Basis (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Assets:
Assets, Fair Value Disclosure	$ 80,045	$ 4,003
Liabilities:
Financial Liabilities Fair Value Disclosure		300
Money Market Funds [Member]
Assets:
Assets, Fair Value Disclosure	80,045	4,003
Series B Preferred Stock Tranche Right Liability [Member]
Liabilities:
Financial Liabilities Fair Value Disclosure		300
Fair Value, Inputs, Level 1 [Member]
Assets:
Assets, Fair Value Disclosure	80,045	4,003
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Assets:
Assets, Fair Value Disclosure	$ 80,045	4,003
Fair Value, Inputs, Level 3 [Member]
Liabilities:
Financial Liabilities Fair Value Disclosure		300
Fair Value, Inputs, Level 3 [Member] | Series B Preferred Stock Tranche Right Liability [Member]
Liabilities:
Financial Liabilities Fair Value Disclosure		$ 300