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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
	Oct. 31, 2015	Oct. 26, 2015	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Class of Stock [Line Items]
Aggregate purchase price					$ 211.3
Treasury Stock [Member]
Class of Stock [Line Items]
Aggregate purchase price					211.3
Stock Repurchase Program Board Authorized Repurchases [Member]
Class of Stock [Line Items]
Stock Repurchase Program, Authorized Amount			$ 250.0		$ 250.0
Shares repurchased (in shares)			2.5	4.4	3.5	8.0
Aggregate purchase price			$ 150.0	$ 235.9	$ 209.1	$ 415.7
Average purchase price per share (in dollars per share)			$ 59.83	$ 53.15	$ 60.54	$ 51.98
Treasury Shares Retirement [Member]
Class of Stock [Line Items]
Treasury Stock, Shares, Retired	43.0
Stock Repurchase Program Board Authorized Repurchases [Member] | Stock Repurchase Program Board Authorized Repurchases [Member]
Class of Stock [Line Items]
Shares repurchased (in shares)		0.4
Aggregate purchase price		$ 24.4
Average purchase price per share (in dollars per share)		$ 60.05
Remaining amount available for share repurchase		$ 297.2

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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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Number of shares that have been repurchased during the period and are being held in treasury.

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Number of shares of common and preferred stock retired from treasury during the period.

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Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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