Earnings (loss) per share - Narrative (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 25, 2022	Jun. 26, 2021	Jun. 25, 2022	Jun. 26, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Performance awards contingent on performance conditions which have not been met yet (in shares)	4,739,895		4,739,895
Dilutive effect of share-based awards (in shares)	0	3,886,000	0	3,544,000
Share-based awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive effect of share-based awards (in shares)	3,878,231		3,919,991