Notes Payable (Tables)

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Summary of Future Principal Payments under Hercules Loan Agreement

As of December 31, 2018 future principal payments, under the Hercules Loan Agreement are as follows:

Years ending December 31,
(In thousands)
2019	$	—
2020		1,466
2021		18,527
2022		10,007
Total		30,000
Less: Unamortized discount		(1,063	)
Notes payable, net of debt discount	$	28,937