Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities not Included in Calculation of Diluted Net Loss Per Share (Details) - shares	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Shares Issuable upon Conversion of Series Seed Convertible
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities not included from calculation of diluted net loss per share		4,444,444
Shares Issuable upon Conversion of Series A Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities not included from calculation of diluted net loss per share		9,961,663
Shares Issuable upon Exercise of Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities not included from calculation of diluted net loss per share	7,469,973
Non-vested Shares under Restricted Stock Grants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities not included from calculation of diluted net loss per share	5,862,440	5,885,865