Collaborative Research and License Agreements (Details) $ in Thousands			3 Months Ended		9 Months Ended
	Nov. 13, 2019 USD ($) agreement	Feb. 17, 2019 USD ($) collaborationTarget	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue			$ 2,443	$ 527	$ 16,473	$ 986
Deferred revenue, current			8,479		8,479		$ 21,873
AbbVie Collaboration | Collaboration Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of collaboration programs | agreement	2
Non-refundable upfront payment received for research agreement	$ 25,000
Collaboration option exercise fee	10,000
Collaboration option exercise fee	$ 10,000
Termination period upon written notice	90 days
Collaboration revenue			2,402		16,351
Deferred revenue, current			8,479		8,479
Dermelix License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Aggregate regulatory milestone revenue		$ 13,500
Potential milestone revenue		152,500
Dermelix License Agreement | Collaboration Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Non-refundable upfront payment received for research agreement		1,000
Collaboration option exercise fee		$ 1,000
Collaboration revenue			$ 41	$ 527	$ 122	$ 986
Number of additional collaboration targets | collaborationTarget		5
Collaboration agreement term		6 years
Collaboration development expenses		$ 1,000
Collaboration option rights usage term		30 days
Development and Commercialization License | AbbVie Collaboration | Collaboration Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration option exercise fee	$ 15,000
Maximum | AbbVie Collaboration | Collaboration Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Development milestone payment	55,000
Product approval and launch milestone payment	132,500
Sales milestone payment	$ 175,000