Net Loss per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net loss	$ (46,867)	$ (4,480)
Net loss per share, basic and diluted (in dollars per share)	$ (1.92)	$ (0.27)
Weighted-average shares outstanding used to compute basic and diluted net loss per share (in shares)	24,402,368	16,527,000
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from the computation of diluted net loss per share (in shares)	3,479,093	0
Common stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	3,257,801	0
Securities excluded from the computation of diluted net loss per share (in shares)	3,257,801	0
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded from the computation of diluted net loss per share (in shares)	221,292	0

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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