Collaborative Research and License Agreements (Details) $ in Thousands		3 Months Ended								12 Months Ended
	Nov. 13, 2019 USD ($) agreements	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) target	Dec. 31, 2018 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Current portion of deferred revenue		$ 21,873				$ 0				$ 21,873	$ 0
Deferred revenue, noncurrent		2,956				0				2,956	0
Collaboration revenue		310	$ 527	$ 434	$ 25	$ 6	$ 57	$ 19	$ 36	$ 1,296	118
Allergan Collaboration | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of collaboration programs	2									2
Collaboration agreement, term	5 years
Non-refundable upfront payment received for research agreement	$ 25,000
Option exercise fee	10,000
Extended option, additional exercise fee	$ 10,000
Termination period upon written notice	90 days
Deferred revenue		24,829								$ 24,829
Current portion of deferred revenue		21,873								21,873
Deferred revenue, noncurrent		2,956								2,956
Licensing fees incurred		$ 3,750
Collaboration revenue										171
Allergan Collaboration | Maximum | Collaborative 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
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 | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration agreement, term										6 years
Non-refundable upfront payment received for research agreement										$ 1,000
Option exercise fee										$ 1,000
Number of additional collaboration targets | target										5
Collaboration development expenses										$ 1,000
Period to exercise upon commencement of SNA technology development										30 days
Collaboration revenue										$ 1,125
Purdue Collaboration
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration revenue										$ 0	$ 118
Development and Commercialization License | Allergan Collaboration | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Option exercise fee	$ 15,000