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Shareholders' Equity - Share repurchase program (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Common shares held in treasury (shares)	219.2	218.5	217.9
Common shares held in treasury, at cost	$ 4,487.0	$ 4,424.0
Authorized Share Repurchase Program
Class of Stock [Line Items]
Aggregate cost of shares repurchased	$ 23.5	$ 0.0	$ 585.8
Number of shares repurchased (shares)	0.3	0.0	12.9
Average price per share repurchased	$ 89.65	$ 0	$ 45.44
Common shares | Authorized Share Repurchase Program
Class of Stock [Line Items]
Remaining share repurchase authorization	$ 996.8
Cumulative number of shares acquired since inception of share repurchase program	433.8
Aggregate purchase price of shares acquired since inception of share repurchase program	$ 5,900.0

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