Commitments and Contingencies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020 USD ($)
Commitments And Contingencies [Line Items]
Outstanding material claims	$ 0
Reserve for indemnification	0
Madrigal Agreement [Member]
Commitments And Contingencies [Line Items]
License fee	$ 250,000
Percentage over future regulatory, development and sales-dependent milestone payments	80.00%
Madrigal Agreement [Member] | Maximum [Member]
Commitments And Contingencies [Line Items]
Future regulatory, development and sales-dependent milestone payments	$ 340,000,000
MEEI Agreement [Member]
Commitments And Contingencies [Line Items]
Additional equity consideration issuable	0
MEEI Agreement [Member] | Second and Third Anniversary [Member]
Commitments And Contingencies [Line Items]
Non-creditable non-refundable license maintenance fees	15,000
MEEI Agreement [Member] | Fourth and Fifth Anniversary [Member]
Commitments And Contingencies [Line Items]
Non-creditable non-refundable license maintenance fees	25,000
MEEI Agreement [Member] | Sixth and Subsequent Anniversary [Member]
Commitments And Contingencies [Line Items]
Non-creditable non-refundable license maintenance fees	$ 35,000