Fair Value Measurements - Schedule of Fair Value Measurement of Assets And Liabilities (Details) - Fair Value on Recurring Basis - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	$ 20,657,038	$ 1,021,897
Total liabilities	0	3,898,944
Cash and Cash Equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	20,657,038	1,021,897
Preferred Stock Warrant Liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total liabilities	0	3,898,944
Fair Value Measurement Using Quoted Prices In Active Markets For Identical Assets Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	20,657,038	1,021,897
Total liabilities	0	0
Fair Value Measurement Using Quoted Prices In Active Markets For Identical Assets Level 1 | Cash and Cash Equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	20,657,038	1,021,897
Fair Value Measurement Using Quoted Prices In Active Markets For Identical Assets Level 1 | Preferred Stock Warrant Liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total liabilities	0	0
Fair Value Measurement Using Significant Other Observable Inputs Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	0	0
Total liabilities	0	0
Fair Value Measurement Using Significant Other Observable Inputs Level 2 | Cash and Cash Equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	0	0
Fair Value Measurement Using Significant Other Observable Inputs Level 2 | Preferred Stock Warrant Liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total liabilities	0	0
Fair Value Measurement Using Significant Unobservable Inputs Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	0	0
Total liabilities	0	3,898,944
Fair Value Measurement Using Significant Unobservable Inputs Level 3 | Cash and Cash Equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total assets	0	0
Fair Value Measurement Using Significant Unobservable Inputs Level 3 | Preferred Stock Warrant Liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total liabilities	$ 0	$ 3,898,944