Description of Business and Basis of Financial Statements (Details) $ in Thousands, € in Millions				6 Months Ended			15 Months Ended
	Apr. 12, 2019 shares	Apr. 11, 2019 USD ($) shares	Apr. 11, 2019 EUR (€) shares	Jun. 30, 2020 USD ($)	Sep. 30, 2019 shares	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Business Acquisition [Line Items]
Accumulated deficit | $				$ 79,856			$ 79,856	$ 59,911
Proceeds from issuance of private placement | $							112,100
Cash and cash equivalents | $				48,607			$ 48,607	$ 29,369
Conversion ratio	0.025
Vital Therapies, Inc.
Business Acquisition [Line Items]
Percentage of shares owned	11.75%
Immunic AG
Business Acquisition [Line Items]
Percentage of shares owned	88.25%
Vital Therapies, Inc. | Immunic AG
Business Acquisition [Line Items]
Exchange ratio		17.17	17.17
Immunic AG | Vital Therapies, Inc.
Business Acquisition [Line Items]
Aggregate consideration issuable (in shares)	8,927,130
Shares owned prior to transaction (in shares)	1,059,269
Immunic AG | Restricted Stock Units | Vital Therapies, Inc.
Business Acquisition [Line Items]
RSUs owned prior to transaction (in shares)	127,500	5,100,000	5,100,000
RSUs issued to date (in shares)					127,500
Private Placement | Immunic AG
Business Acquisition [Line Items]
Shares issued in private placement transaction (in shares)		2,197,742	2,197,742
Aggregate consideration from private placement		$ 29,900	€ 26.7
April 2020 Equity Issuances
Business Acquisition [Line Items]
Proceeds from issuance of common stock | $				$ 13,918		$ 0