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Shareholders' Equity (Shares Repurchased Under Share Repurchase Program) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Oct. 26, 2016
Class of Stock [Line Items]
Aggregate purchase price			$ 472.5
Stock Repurchase Program Board Authorized Repurchases [Member]
Class of Stock [Line Items]
Shares repurchased (in shares)	1.0	2.5	9.9	3.5
Aggregate purchase price	$ 50.0	$ 150.0	$ 470.6	$ 209.1
Average purchase price per share (in dollars per share)	$ 48.62	$ 59.83	$ 47.48	$ 60.54
Subsequent Event [Member] | Stock Repurchase Program Board Authorized Repurchases [Member]
Class of Stock [Line Items]
Remaining amount available for share repurchase					$ 315.9
Stock Repurchase Program, Authorized Amount					$ 250.0

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Amount of stock repurchase plan authorized.

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Amount remaining of a 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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-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 45
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Number of shares that have been repurchased during the period and are being held in treasury.

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-Topic 505
-SubTopic 10
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-Paragraph 1
-Subparagraph (SX 210.3-04)
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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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