Debt - December 2016 Convertible debt (Details)		1 Months Ended				12 Months Ended
	Mar. 16, 2018 USD ($) shares	Jan. 31, 2019 USD ($) shares	Aug. 31, 2018 USD ($) shares	Jul. 31, 2017 USD ($) Lender	Dec. 31, 2016 USD ($) $ / shares Lender	Dec. 31, 2018 item	Dec. 31, 2019 USD ($)	Jun. 30, 2017 USD ($)
Convertible promissory notes, December 2016
Debt
Aggregate principal amount					$ 2,500,000
Number of lenders | Lender					3
Proceeds from issuance of convertible debt					$ 2,000,000
Unamortized note discount					$ 500,000
Conversion price (in dollars per share) | $ / shares					$ 64.75
Revised principal value of debt								$ 2,600,000
Fair value of notes					$ 11,200,000
Difference between the fair value of the notes and the principal balance					$ 1,000,000
Amortization period of such difference amount					29 months
Interest Payable	$ 535,000		$ 480,000
Debt legal fee	$ 170,000
Repayment of accrued interest		$ 447,000
Shares issued (in shares) | shares	4,081	19,751	4,582
Convertible promissory notes, December 2016 | Convertible Long-term Debt
Debt
Number of debt instrument extinguished | item						2
Unamortized balance of notes payable							$ 0
Convertible note purchase agreement
Debt
Aggregate principal amount					$ 12,500,000
Interest rate (as a percent)				10.00%
Debt instrument, frequency of periodic payment				P6M
Accrued interest capitalized to principal of debt								$ 125,000
Convertible promissory notes, July 2017
Debt
Aggregate principal amount				$ 7,500,000
Number of lenders | Lender				4
Proceeds from issuance of convertible debt				$ 6,000,000
Unamortized note discount				$ 1,500,000