(Loss) earnings per share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Earnings Per Share [Abstract]
Net (loss) income attributable to shareholders	$ (22.4)	$ 21.5	$ 13.2	$ 635.2
Weighted average number of shares outstanding (in shares)	290,732,375	290,059,492	290,566,743	289,993,208
Dilutive effect of share-based awards (in shares)	0	1,743,262	1,149,764	1,870,765
Diluted weighted average number of shares outstanding (in shares)	290,732,375	291,802,754	291,716,507	291,863,973
Number of anti-dilutive shares excluded from diluted (loss) earnings per share calculation (in shares)	6,317,804	3,538,711	5,597,575	3,674,486
Basic (loss) earnings per share (in usd per share)	$ (0.08)	$ 0.07	$ 0.05	$ 2.19
Diluted (loss) earnings per share (in usd per share)	$ (0.08)	$ 0.07	$ 0.05	$ 2.18