Commitments and Contingencies (Details)				9 Months Ended
	Jun. 30, 2022 EUR (€)	Jun. 22, 2021	Apr. 23, 2021	Sep. 30, 2022 EUR (€) licensed_product shares	Sep. 30, 2022 USD ($) licensed_product shares	Sep. 08, 2021 USD ($)
Commitments and contingencies
Litigation stay period (in days)		60 days	10 days
Settled Litigation
Commitments and contingencies
Settlement to be paid						$ 29,000,000
Inception 4
Commitments and contingencies
Contingent consideration arrangements, maximum amount					$ 105,000,000
Share price calculation base, period (in days)				5 days	5 days
Contingent consideration arrangements, maximum amount (in shares) | shares					7,200,000
Contingent consideration arrangements, contingently issuable shares as a percentage of shares outstanding				19.90%	19.90%
GA Product | Inception 4
Commitments and contingencies
Clinical and marketing approval milestones					$ 45,000,000
Wet AMD Product | Inception 4
Commitments and contingencies
Clinical and marketing approval milestones					60,000,000
DelSiTech | Avacincaptad Pegol | License Agreement
Commitments and contingencies
Payments for license fees | €	€ 1,250,000
Achievement of specified clinical and regulatory milestones | Archemix | C5 Licensed Product | Maximum | License Agreement
Commitments and contingencies
Amount to be paid on achievement of milestone					50,500,000
Achievement of specified clinical and regulatory milestones | University Of Massachusetts (UMass) | miniCEP290 | License Agreement | Research and Development Expense
Commitments and contingencies
Payments for license fees					$ 14,750,000
Shares issued for license fees (in shares) | shares				75,000	75,000
First indication | Archemix | C5 Licensed Product | Maximum | License Agreement
Commitments and contingencies
Amount to be paid on achievement of milestone					$ 24,500,000
Second and third indication | Archemix | C5 Licensed Product | Maximum | License Agreement
Commitments and contingencies
Amount to be paid on achievement of milestone					23,500,000
Sustained delivery applications | Archemix | C5 Licensed Product | Maximum | License Agreement
Commitments and contingencies
Amount to be paid on achievement of milestone					2,500,000
Achievement of specified commercial milestones | Archemix | C5 Licensed Product | Maximum | License Agreement
Commitments and contingencies
Amount to be paid on achievement of milestone					22,500,000
Achievement of specified clinical and development milestones | DelSiTech | Avacincaptad Pegol | License Agreement
Commitments and contingencies
Amount to be paid on achievement of milestone | €	35,000,000
Achievement of specified commercial sales milestones | DelSiTech | Avacincaptad Pegol | License Agreement
Commitments and contingencies
Payments for license fees | €	€ 60,000,000			€ 60,000,000
Specified clinical, marketing approval and reimbursement approval milestones with respect to a licensed product | University of Florida Research Foundation (UFRF) | RHO-adRP License Agreement
Commitments and contingencies
Amount to be paid on achievement of milestone					$ 23,500,000
Specified clinical, marketing approval and reimbursement approval milestones with respect to a licensed product | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | BEST1 License Agreement | Research and Development Expense
Commitments and contingencies
Number of licensed products | licensed_product				1	1
Specified clinical, marketing approval and reimbursement approval milestones with respect to a licensed product | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | Primary Licensed Product | BEST1 License Agreement | Research and Development Expense
Commitments and contingencies
Payments for license fees					$ 15,700,000
Specified clinical, marketing approval and reimbursement approval milestones with respect to a licensed product | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | Other Licensed Product | BEST1 License Agreement | Research and Development Expense
Commitments and contingencies
Payments for license fees					3,100,000
Specified commercial sales milestones with respect to a licensed product | University of Florida Research Foundation (UFRF) | RHO-adRP License Agreement
Commitments and contingencies
Amount to be paid on achievement of milestone					$ 70,000,000
Specified commercial sales milestones with respect to a licensed product | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | BEST1 License Agreement | Research and Development Expense
Commitments and contingencies
Number of licensed products | licensed_product				1	1
Specified commercial sales milestones with respect to a licensed product | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | Primary Licensed Product | BEST1 License Agreement | Research and Development Expense
Commitments and contingencies
Payments for license fees					$ 48,000,000
Specified commercial sales milestones with respect to a licensed product | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | Other Licensed Product | BEST1 License Agreement | Research and Development Expense
Commitments and contingencies
Payments for license fees					9,600,000
Specified commercial sales milestones with respect to a licensed product | University Of Massachusetts (UMass) | miniCEP290 | License Agreement | Research and Development Expense
Commitments and contingencies
Payments for license fees					$ 48,000,000