Commitments and Contingencies - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended				6 Months Ended	12 Months Ended
	Jan. 31, 2020	Aug. 31, 2018	Oct. 31, 2016	Jun. 30, 2016	Jun. 30, 2020	Dec. 31, 2019	Jan. 31, 2017
Loss Contingencies [Line Items]
Deferred Revenue					$ 300
Carna Collaboration Agreement [Member]
Loss Contingencies [Line Items]
Upfront License Fee					300
Deferred Revenue					300
Carna License Agreement [Member]
Loss Contingencies [Line Items]
Upfront payment paid				$ 900
CPF License Agreements [Member]
Loss Contingencies [Line Items]
Aggregate milestone payment					19,500
Milestone payment							$ 2,000
Upfront payment paid			$ 7,000
Additional milestone payment payable					319,500
CPF License Agreements [Member] | Phase 1 Clinical Trial in the US [Member]
Loss Contingencies [Line Items]
Milestone payment					7,500
CPF License Agreements [Member] | Phase Two Clinical Trial [Member]
Loss Contingencies [Line Items]
Milestone payment					12,000
Asset Purchase Agreement [Member]
Loss Contingencies [Line Items]
Aggregate milestone payment					190,000
Expense included research and development cost						$ 10,500
Upfront payment paid		$ 3,000
Additional Exepense included Research and development cost					$ 1,500
Asset Purchase Agreement Amendment [Member] | Gilead [Member]
Loss Contingencies [Line Items]
Stock issued, shares	725,283
Number of securitites called by warrants and rights	725,283				725,283
Excercise price of warrants or rights	$ 13.20