Stock-Based Compensation Plans - Summary of Stock Option Activity (Details)	6 Months Ended
	Jun. 30, 2020 USD ($) $ / shares shares
Employee Stock Options, Vital Therapies Inc.
Options
Outstanding, Beginning balance (in shares) | shares	14,403
Granted (in shares) | shares	0
Exercised (in shares) | shares	0
Forfeited or expired (in shares) | shares	0
Outstanding, Ending balance (in shares) | shares	14,403
Options vested and expected to vest, Ending balance (in shares) | shares	14,403
Options exercisable, Ending balance (in shares) | shares	14,403
Weighted- Average Exercise Price
Outstanding, Beginning balance (usd per share) | $ / shares	$ 306.01
Granted (usd per share) | $ / shares	0
Exercised (usd per share) | $ / shares	0
Forfeited or expired (usd per share) | $ / shares	0
Outstanding, Ending balance (usd per share) | $ / shares	306.01
Options vested and expected to vest, Weighted-Average Exercise Price, Ending balance (usd per share) | $ / shares	306.01
Options exercisable, Weighted-Average Exercise Price, Ending balance (usd per share) | $ / shares	$ 306.01
Other Disclosures
Outstanding, Weighted-Average Remaining Contractual Term, Ending balance	2 years 1 month 2 days
Options vested and expected to vest , Weighted-Average Remaining Contractual Term, Ending balance	2 years 1 month 2 days
Options exercisable, Weighted-Average Remaining Contractual Term, Ending balance	2 years 1 month 2 days
Outstanding, Aggregate Intrinsic Value, Ending balance | $	$ 0
Options vested and expected to vest , Aggregate Intrinsic Value, Ending balance | $	0
Options exercisable, Aggregate Intrinsic Value, Ending balance | $	$ 0
2019 Omnibus Equity Incentive Plan | Outstanding stock options
Options
Outstanding, Beginning balance (in shares) | shares	456,645
Granted (in shares) | shares	25,118
Exercised (in shares) | shares	0
Forfeited or expired (in shares) | shares	(61,918)
Outstanding, Ending balance (in shares) | shares	419,845
Options vested and expected to vest, Ending balance (in shares) | shares	419,845
Options exercisable, Ending balance (in shares) | shares	101,845
Weighted- Average Exercise Price
Outstanding, Beginning balance (usd per share) | $ / shares	$ 12.57
Granted (usd per share) | $ / shares	8.30
Exercised (usd per share) | $ / shares	0
Forfeited or expired (usd per share) | $ / shares	13.47
Outstanding, Ending balance (usd per share) | $ / shares	12.19
Options vested and expected to vest, Weighted-Average Exercise Price, Ending balance (usd per share) | $ / shares	12.19
Options exercisable, Weighted-Average Exercise Price, Ending balance (usd per share) | $ / shares	$ 12.61
Other Disclosures
Outstanding, Weighted-Average Remaining Contractual Term, Ending balance	8 years 9 months
Options vested and expected to vest , Weighted-Average Remaining Contractual Term, Ending balance	8 years 9 months
Options exercisable, Weighted-Average Remaining Contractual Term, Ending balance	7 years 4 months 6 days
Outstanding, Aggregate Intrinsic Value, Ending balance | $	$ 411,847
Options vested and expected to vest , Aggregate Intrinsic Value, Ending balance | $	411,847
Options exercisable, Aggregate Intrinsic Value, Ending balance | $	$ 72,388