Commitments and Contingencies (Details)	3 Months Ended
	Mar. 31, 2023 USD ($) shares	Jun. 30, 2022 EUR (€)	Sep. 30, 2022 EUR (€)
Inception 4
Commitments and contingencies
Contingent consideration arrangements, maximum amount	$ 105,000,000
Share price calculation base, period (in 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%
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
Agilent | Avacincaptad Pegol Drug Substance - Agilent Technologies, Inc.
Commitments and contingencies
Contract term	7 years
Automatic renewal periods	2 years
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
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 commercial sales milestones | DelSiTech | Avacincaptad Pegol | License Agreement
Commitments and contingencies
Payments for license fees | €		€ 60,000,000
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
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