Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Cash flows from operating activities:
Net loss	$ (13.4)	$ (153.8)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2.3	3.5
Net accretion of bond discounts/premiums	(10.4)	(17.1)
Amortization of right-of-use assets	1.7	1.5
Amortization of collaboration contract asset	4.1	3.6
Net loss on disposal of property, plant and equipment	0.0	2.6
Stock-based compensation	35.5	64.9
Changes in operating assets and liabilities:
Accounts receivable	(14.6)	(7.3)
Other receivables	1.5	(0.3)
Prepaid expenses and other assets	2.3	(6.4)
Collaboration contract asset	0.0	(3.0)
Accounts payable and accrued liabilities	(17.7)	(16.3)
Operating lease liability	(1.6)	(1.6)
Deferred revenue	(233.1)	(45.5)
Net cash used in operating activities	(243.4)	(175.2)
Cash flows from investing activities:
Purchases of marketable securities	(347.6)	(600.8)
Maturities of marketable securities	611.1	538.0
Purchases of property, equipment and leasehold improvements	(1.7)	(1.5)
Proceeds from disposal of property, equipment and leaseholds improvements	0.0	0.1
Net cash provided by (used in) investing activities	261.8	(64.2)
Cash flows from financing activities:
Repayments of long-term debt	(0.1)	(0.3)
Repurchase of common shares	(17.8)	0.0
Proceeds from exercise of stock options and issuance of ESPP shares	0.5	7.7
Net cash (used in) provided by financing activities	(17.4)	7.4
Net increase (decrease) in cash and cash equivalents	1.0	(232.0)
Cash, cash equivalents and restricted cash, beginning of the period	100.5	317.2
Cash and cash equivalents, end of the period	101.5	85.2
Supplemental disclosure of cash flow information:
Repurchases of common shares unpaid at period end	2.5	0.0
Cash paid for taxes	$ 0.3	$ 1.6