Summary of Significant Accounting Policies - Net Loss Per Share and Segment Information (Details)	12 Months Ended
	Dec. 31, 2018 segment shares	Dec. 31, 2017 shares
Antidilutive common stock equivalents excluded from computation of diluted net loss per share
Anti-dilutive securities excluded from the calculation of diluted net loss per share (in shares)	4,635,838	285,731
Segment Information
Number of operating segments | segment	1
Stock options
Antidilutive common stock equivalents excluded from computation of diluted net loss per share
Anti-dilutive securities excluded from the calculation of diluted net loss per share (in shares)	433,389	283,277
Common stock warrants
Antidilutive common stock equivalents excluded from computation of diluted net loss per share
Anti-dilutive securities excluded from the calculation of diluted net loss per share (in shares)	4,202,449	2,454