Accounting policies - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 30, 2024	Apr. 01, 2023	Dec. 30, 2023
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) financing activities	$ (19)	$ (30)
Net cash provided by (used in) operating activities	10	62
Increase (decrease) in cash and cash equivalents	(18)	1
Supplier finance program, obligation	$ 128		$ 142
Revision of Prior Period, Error Correction, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) financing activities		6
Net cash provided by (used in) operating activities		5
Increase (decrease) in cash and cash equivalents		$ 1
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Supplier finance program general payment timing, period	0 days
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Supplier finance program general payment timing, period	135 days