Private Placement (Details) - USD ($) $ / shares in Units, $ in Thousands				9 Months Ended
	Aug. 09, 2019	Mar. 28, 2019	Aug. 06, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Class of Stock [Line Items]
Number of shares issued (in shares)			12,062,000
Common stock, par value (in dollars per share)			$ 0.001	$ 0.001		$ 0.001
Number of additional shares from warrants (in shares)		2,500,000	4,221,700
Gross proceeds			$ 19,700
Stock issuance costs			$ 500
Initial exercise price of warrants (in dollars per share)		$ 7.00	$ 2.52
Proceeds from the exercise of warrant to purchase common stock		$ 10,600		$ 10,639	$ 0
Preferred stock issued during the period				$ 10,000	$ 0
Series E Preferred Stock
Class of Stock [Line Items]
Preferred stock issued (in shares)	10,000			10,000		0
Preferred stock issued during the period	$ 10,000
Dividend rate	9.00%
Redemption price, percent	110.00%
Base amount (in dollars per share)	$ 1,000			$ 1,000		$ 0