Warrants - Stock Warrant Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Warrants to purchase Common Stock
Number
Beginning balance (in shares)	49,349	7,031
Warrants acquired in Merger (in shares)		13,534
Preferred stock warrants converted into Common Stock warrants (in shares)		25,779
Granted (in shares)		24,097
Exercised (in shares)		(21,092)
Activity (in shares)	0
Ending balance (in shares)	49,349	49,349
Weighted Average Exercise Price
Beginning balance (in usd per share)	$ 27.65	$ 0.57
Warrants acquired in Merger (in usd per share)		80.70
Preferred stock warrants converted into Common Stock warrants (in usd per share)		6.21
Granted (in usd per share)		7.15
Exercised (in usd per share)		3.04
Activity (in usd per share)	0.00
Ending balance (in usd per share)	$ 27.65	$ 27.65
Preferred Stock Warrants [Member]
Number
Beginning balance (in shares)	0	25,779
Warrants acquired in Merger (in shares)		0
Preferred stock warrants converted into Common Stock warrants (in shares)		(25,779)
Granted (in shares)		0
Exercised (in shares)		0
Activity (in shares)	0
Ending balance (in shares)	0	0
Weighted Average Exercise Price
Beginning balance (in usd per share)	$ 0.00	$ 6.21
Warrants acquired in Merger (in usd per share)		0.00
Preferred stock warrants converted into Common Stock warrants (in usd per share)		6.21
Granted (in usd per share)		0.00
Exercised (in usd per share)		0.00
Activity (in usd per share)	0.00
Ending balance (in usd per share)	$ 0.00	$ 0.00