Shareholders' Deficit - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Class of Warrant or Right [Line Items]
Proceeds upon exercise of stock options	$ 2,712	$ 108
Issuance of common stock upon exercise of stock options (in shares)	306,857	10,744
Warrants to purchase common stock
Class of Warrant or Right [Line Items]
Warrants outstanding	243,115		243,115
Warrant exercise price (in USD per share)	$ 20.68		$ 20.68

Exercise price per share or per unit of warrants or rights outstanding.

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