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Commitments and Contingencies - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended
	Apr. 30, 2018	Mar. 31, 2020	Mar. 31, 2019
Loss Contingencies [Line Items]
Operating leases, rent expense		$ 60,000	$ 27,000
Teva Agreements
Loss Contingencies [Line Items]
Nonrefundable upfront payment	$ 6,000,000
Payment upon achievement of certain clinical and commercial milestones	135,000,000
Asset transfer and license agreement, termination period after written notice			120 days
Asset transfer and license agreement, termination period notice of breach			60 days
Asset transfer and license agreement termination notice period if bankruptcy petition filed			60 days
Teva Agreements | Research and Development Expenses
Loss Contingencies [Line Items]
Up-front license payment		$ 0	$ 0
Teva Agreements | Teva’s GlycoPEGylated FGF21 Program
Loss Contingencies [Line Items]
Payment upon achievement of certain clinical and commercial milestones	67,500,000
Teva Agreements | Teva’s Development Program
Loss Contingencies [Line Items]
Payment upon achievement of certain clinical and commercial milestones	$ 67,500,000

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