Operating leases - Supplemental Operating Leases Information Table (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 28, 2024	Sep. 30, 2023	Sep. 28, 2024	Sep. 30, 2023
Lessee, Lease, Description [Line Items]
Operating cash flows from operating leases	$ 4	$ 0	$ 9	$ 0
Right-of-use assets obtained in exchange for operating lease liabilities
Right-of-use assets obtained in exchange for operating lease liabilities	34		82
New leases
Right-of-use assets obtained in exchange for operating lease liabilities
Right-of-use assets obtained in exchange for operating lease liabilities	35	0	87	0
Modified leases
Right-of-use assets obtained in exchange for operating lease liabilities
Right-of-use assets obtained in exchange for operating lease liabilities	$ 0	$ 0	$ 0	$ 0