Debt Financing - Future Minimum Payments (Details) $ in Thousands	Jun. 30, 2019 USD ($)
Debt Principal [Abstract]
Remainder of 2019	$ 1,508
2020	3,359
2021	2,964
2022	359
Total	8,190
Debt Interest Payment [Abstract]
Remainder of 2019	363
2020	530
2021	194
2022	12
Total	1,099
Debt Purchase Option Fee [Abstract]
Remainder of 2019	0
2020	0
2021	600
2022	612
Total	$ 1,212

Amount of long-term debt payable, sinking fund requirements, and other securities issued that are redeemable by holder at fixed or determinable prices and dates maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04.(a))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6802200&loc=d3e1835-112601