Licensing and Commercialization Agreement (Details) $ in Thousands		1 Months Ended							8 Months Ended	12 Months Ended	110 Months Ended
	Jul. 22, 2019 shares	Oct. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)	Sep. 30, 2019 USD ($)	Jul. 31, 2019 USD ($) shares	May 31, 2019 USD ($) licensedProduct shares	Jun. 30, 2018 USD ($)	Sep. 30, 2011 USD ($) shares	Oct. 31, 2020 milestone_payment_number	Dec. 31, 2020	Oct. 31, 2020 USD ($)	Dec. 31, 2018 USD ($)
Agreement
Number of licensed products \| licensedProduct						1
RHO-adRP License Agreement \| University of Florida Research Foundation (UFRF)
Agreement
Licensing agreement term							10 years
RHO-adRP License Agreement \| University of Florida Research Foundation (UFRF) \| Specified Clinical, Marketing Approval and Reimbursement Approval Milestones Related to a Licensed Product
Agreement
Amount to be paid on achievement of milestone												$ 23,500
RHO-adRP License Agreement \| University of Florida Research Foundation (UFRF) \| Specified Commercial Sales Milestones Related to a Licensed Product
Agreement
Amount to be paid on achievement of milestone												$ 70,000
BEST1 License Agreement \| University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn)
Agreement
Licensing agreement term						10 years
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
Research and development \| BEST1 License Agreement \| University Of Pennsylvania \| Specified Clinical, Marketing Approval and Reimbursement Approval Milestones Related to a Licensed Product \| Primary Licensed Product
Agreement
Payments for license fees						$ 200
Research and development \| BEST1 License Agreement \| University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) \| Specified Clinical, Marketing Approval and Reimbursement Approval Milestones Related to a Licensed Product \| Primary Licensed Product
Agreement
Payments for license fees						15,700
Research and development \| BEST1 License Agreement \| University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) \| Specified Clinical, Marketing Approval and Reimbursement Approval Milestones Related to a Licensed Product \| Other Licensed Product
Agreement
Payments for license fees						3,100
Research and development \| BEST1 License Agreement \| University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) \| Specified Commercial Sales Milestones Related to a Licensed Product \| Primary Licensed Product
Agreement
Payments for license fees						48,000
Research and development \| BEST1 License Agreement \| University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) \| Specified Commercial Sales Milestones Related to a Licensed Product \| Other Licensed Product
Agreement
Payments for license fees						9,600
General and administrative \| RHO-adRP License Agreement \| University of Florida Research Foundation (UFRF)
Agreement
Payments for license fees							$ 30
General and administrative \| BEST1 License Agreement \| University of Florida Research Foundation (UFRF) \| Specified Clinical, Marketing Approval and Reimbursement Approval Milestones Related to a Licensed Product \| Primary Licensed Product
Agreement
Payments for license fees						18
License Agreements \| Archemix \| C5 Licensed Product
Agreement
Licensing agreement term								12 years
License Agreements \| Archemix \| Achievement of specified clinical and regulatory milestones \| C5 Licensed Product
Agreement
Payments for license fees		$ 6,000	$ 1,000					$ 1,000			$ 9,000
Number of milestone payments \| milestone_payment_number									2
Trial data period										12 months
License Agreements \| Archemix \| First indication \| C5 Licensed Product
Agreement
Amount to be paid on achievement of milestone								24,500
License Agreements \| Archemix \| Second and third indication \| C5 Licensed Product
Agreement
Amount to be paid on achievement of milestone								23,500
License Agreements \| Archemix \| Sustained delivery applications \| C5 Licensed Product
Agreement
Amount to be paid on achievement of milestone								$ 2,500
License Agreements \| University Of Massachusetts (UMass) \| miniCEP290
Agreement
Shares issued for license fees (in shares) \| shares	75,000				75,000
Licensing agreement term					10 years
License Agreements \| Research and development \| University Of Massachusetts (UMass) \| miniCEP290
Agreement
Payments for license fees				$ 400
License Agreements \| Research and development \| University Of Massachusetts (UMass) \| Achievement of specified clinical and regulatory milestones \| miniCEP290
Agreement
Payments for license fees					$ 14,750	$ 14,750
Shares issued for license fees (in shares) \| shares					75,000	75,000
License Agreements \| Research and development \| University Of Massachusetts (UMass) \| Specified Commercial Sales Milestones Related to a Licensed Product \| miniCEP290
Agreement
Payments for license fees					$ 48,000	$ 48,000
License Agreements \| General and administrative \| University Of Massachusetts (UMass) \| miniCEP290
Agreement
Payments for license fees				$ 18
License Agreements \| Series A Preferred Stock \| Archemix \| Achievement of specified clinical and regulatory milestones \| C5 Licensed Product
Agreement
Shares issued for license fees (in shares) \| shares								2,000,000
License Agreements \| Series B Preferred Stock \| Archemix \| Achievement of specified clinical and regulatory milestones \| C5 Licensed Product
Agreement
Shares issued for license fees (in shares) \| shares								500,000
Maximum \| License Agreements \| Archemix \| Achievement of specified clinical and regulatory milestones \| C5 Licensed Product
Agreement
Amount to be paid on achievement of milestone								$ 50,500
Maximum \| License Agreements \| Archemix \| First indication \| C5 Licensed Product
Agreement
Amount to be paid on achievement of milestone								24,500
Maximum \| License Agreements \| Archemix \| Second and third indication \| C5 Licensed Product
Agreement
Amount to be paid on achievement of milestone								23,500
Maximum \| License Agreements \| Archemix \| Sustained delivery applications \| C5 Licensed Product
Agreement
Amount to be paid on achievement of milestone								2,500
Maximum \| License Agreements \| Archemix \| Achievement of specified commercial milestones \| C5 Licensed Product
Agreement
Amount to be paid on achievement of milestone								$ 22,500