Earnings per share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 28, 2020	Mar. 30, 2019
Earnings Per Share [Abstract]
Net income attributable to shareholders	$ 35.6	$ 613.7
Weighted average number of shares outstanding (in shares)	290,609,974	289,928,526
Dilutive effect of share-based awards (in shares)	1,501,279	4,733,387
Diluted weighted average number of shares outstanding (in shares)	292,111,253	294,661,913
Basic earnings per share (in usd per share)	$ 0.12	$ 2.12
Diluted earnings per share (in usd per share)	$ 0.12	$ 2.08
Anti-dilutive shares excluded from diluted income per share calculation (in shares)	5,508,174	3,809,508