Notes Payable - Schedule of Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Notes Payable [Abstract]
2022	$ 48,077
Total before unamortized discount and issuance costs	48,077
Less: paid-in-kind interest	(3,284)
Less: unamortized discount and issuance costs	(1,891)
Total notes payable	$ 42,902	$ 42,373