Licensing and Commercialization Agreement (Details) - USD ($) $ in Thousands	1 Months Ended							3 Months Ended								12 Months Ended			22 Months Ended
	Jun. 30, 2018	Aug. 31, 2017	Jul. 31, 2017	Jun. 30, 2016	Mar. 31, 2015	Sep. 30, 2014	May 31, 2014	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2016
Agreement
Upfront fees received		$ 16,900
Total collaboration revenue								$ 0	$ 0	$ 0	$ 0	$ 0	$ 206,654	$ 1,661	$ 1,662	$ 0	$ 209,977	$ 50,909
License revenue
Agreement
Total collaboration revenue																0	152,912	22,937
Research and development activity revenue
Agreement
Total collaboration revenue																0	56,180	9,741
API transfer revenue
Agreement
Total collaboration revenue																0	754	18,212
Joint operating committee revenue
Agreement
Total collaboration revenue																$ 0	$ 131	$ 19
Licensing and Commercialization Agreement | Novartis Pharma AG
Agreement
Upfront fees received			$ 189,800				$ 200,000
Total collaboration revenue													$ 206,700
Licensing and Commercialization Agreement | Novartis Pharma AG | Achievement of specified patient enrollment milestones
Agreement
Patient enrollment-based milestone revenue achieved				$ 30,000	$ 50,000	$ 50,000													$ 130,000
Research and development | RHO-adRP License Agreement | University of Florida Research Foundation (UFRF)
Agreement
Payments for license fees	$ 500
Research and development | RHO-adRP License Agreement | University of Florida Research Foundation (UFRF) | Specified Clinical, Marketing Approval and Reimbursement Approval Milestones Related to a Licensed Product
Agreement
Payments for license fees	23,500
Research and development | RHO-adRP License Agreement | University of Florida Research Foundation (UFRF) | Specified Commercial Sales Milestones Related to a Licensed Product
Agreement
Payments for license fees	70,000
General and administrative | RHO-adRP License Agreement | University of Florida Research Foundation (UFRF)
Agreement
Payments for license fees	$ 30