Credit Facility and Term Loans - Additional Information (Details) - USD ($)		3 Months Ended		12 Months Ended
	Nov. 23, 2018	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2019
Debt Instrument [Line Items]
Available balance of credit facility					$ 0
Interest expense of credit facilities		$ 500,000	$ 700,000
Deferred debt issuance costs		200,000	100,000
Borrowings, outstanding		37,400,000			35,100,000
Interest expense		1,133,000	1,213,000
Term Loan
Debt Instrument [Line Items]
Credit facility maximum borrowing amount				$ 15,000,000
Debt instrument maturity month and year				2023-01
Borrowings, outstanding		15,000,000			15,000,000
Interest expense		500,000	500,000
Horizon Term Loan
Debt Instrument [Line Items]
Debt offset against and expense over the term				5 years
Deferred debt issuance costs		767,000		$ 1,000,000	836,000
Warrants term				10 years
Fair value on issuance				$ 900,000
Debt discount				$ 900,000
Horizon Term Loan | Common Stock
Debt Instrument [Line Items]
Warrants to purchase shares				76,923
Warrants to purchase shares, exercise price				$ 15.60
Maximum
Debt Instrument [Line Items]
Available balance of credit facility		100,000
Maximum | Term Loan
Debt Instrument [Line Items]
Debt issuance costs		$ 100,000	$ 100,000
London Interbank Offered Rate ("LIBOR") | Term Loan
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate				9.90%
Description of variable rate basis		one-month LIBOR
London Interbank Offered Rate ("LIBOR") | Minimum | Term Loan
Debt Instrument [Line Items]
Potential additional interest				2.50%
Mid Cap Prior Credit Facility
Debt Instrument [Line Items]
Unamortized debt issuance costs				$ 700,000
Mid Cap Credit Facility
Debt Instrument [Line Items]
Credit facility maximum borrowing amount	$ 25,000,000
Additional increase in borrowing amount	$ 50,000,000
Line of credit facility, unused capacity, commitment fee percentage	0.50%
Line of credit facility, minimum liquidity financial covenant requirement in cash on hand	$ 5,000,000
Debt issuance costs				$ 1,300,000
Debt offset against and expense over the term				3 years
Line of credit, outstanding		$ 25,000,000			23,000,000
Available balance of credit facility					$ 0
Current borrowing capacity				$ 25,000,000
Mid Cap Credit Facility | Maximum
Debt Instrument [Line Items]
Available balance of credit facility		$ 100,000
Mid Cap Credit Facility | London Interbank Offered Rate ("LIBOR")
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	5.75%
Credit Facility and Term Loan
Debt Instrument [Line Items]
Line of credit facility covenant minimum liquidity requirement in unrestricted cash				$ 5,000,000