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Shareholders' Equity (Shares Repurchased Under Share Repurchase Program) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended	3 Months Ended					9 Months Ended
	Apr. 30, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Oct. 20, 2021
Class of Stock [Line Items]
Aggregate purchase price		$ 879.2	$ 736.1	$ 306.1		$ 80.0
Shares of treasury stock retired	16.0
Stock Repurchase Program Board Authorized Repurchases [Member]
Class of Stock [Line Items]
Shares repurchased (in shares)		7.9			0.0		19.2	2.5
Aggregate purchase price		$ 879.2			$ 0.0		$ 1,921.4	$ 80.0
Average purchase price per share (in dollars per share)		$ 111.96			$ 0		$ 100.13	$ 31.95
Remaining amount available for share repurchase		$ 276.3					$ 276.3
Stock Repurchase Program Board Authorized Repurchases [Member] | Subsequent Event [Member]
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount									$ 1,000.0

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Amount of stock repurchase plan authorized.

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Total cost of shares repurchased divided by the total number of shares repurchased.

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