Debt - Term Loans (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended		9 Months Ended
	Aug. 31, 2020	Jun. 27, 2017	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Sep. 12, 2017
Line of Credit Facility [Line Items]
Final payment fee			$ 2,300		$ 2,300
Class of warrant or right, number of securities called by warrants or rights (in shares)	196,850
Exercise price (in dollars per share)	$ 2.54		$ 1.58		$ 1.58		$ 1.12
Class of warrant or right, expiration period	10 years
Issuance of common warrants with long-term debt, net	$ 400
Loss on extinguishment of debt			$ 461	$ 0	$ 461	$ 0
Interest expense			365	388	$ 843	1,184
Stock warrants to purchase common stock
Line of Credit Facility [Line Items]
Sale of stock, number of shares issued in transaction (in shares)		79,130
Exercise price (in dollars per share)		$ 17.71
2020 Term Loans
Line of Credit Facility [Line Items]
Maximum borrowing capacity	35,000
Debt instrument, additional accrued interest in the event of default					0.050
Debt instrument, redemption price, percentage of principal amount redeemed					9.00%
Debt instrument, default, bankruptcy, or insolvency value of triggering accelerated redemption	500
Term loan facility			25,000		$ 25,000
Debt issuance costs, line of credit arrangements (less than)			400		$ 400
2020 Term Loans | Maximum
Line of Credit Facility [Line Items]
Debt instrument, prepayment fee, percentage					0.030
2020 Term Loans | Minimum
Line of Credit Facility [Line Items]
Debt instrument, prepayment fee, percentage					0.010
2020 Term Loans | Debt Instrument, Redemption, Period One [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate					7.90%
2020 Term Loans | Debt Instrument, Redemption, Period Two [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate					4.65%
2020 Term Loans | Debt Instrument, Redemption, Period Three [Member]
Line of Credit Facility [Line Items]
Basis spread on variable rate					10.00%
2017 Term Loans
Line of Credit Facility [Line Items]
Repayments of lines of credit					$ 13,700
Loss on extinguishment of debt			500
Term loan facility			18,200		18,200			$ 21,000
Debt issuance costs, line of credit arrangements (less than)								$ 100
Interest expense			$ 300	$ 400	$ 800	$ 1,200
Term A Loans
Line of Credit Facility [Line Items]
Maximum borrowing capacity	25,000
Term B Loans
Line of Credit Facility [Line Items]
Maximum borrowing capacity	10,000
Term B Loans | Stock warrants to purchase common stock
Line of Credit Facility [Line Items]
Sale common stock	$ 200,000