Shareholders' Equity (Narrative) (Details) (USD $) In Millions, except Per Share data	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Class of Stock [Line Items]
Available for share repurchases under the share repurchase program	$ 117.6		$ 117.6
Shares repurchased	5.7	2.9	10.8	25.9
Aggregate purchase price	195.9	55.0	365.6	506.6
Average purchase price per share	$ 34.66	$ 19.08	$ 33.85	$ 19.59
Repurchase of Equity [Member]
Class of Stock [Line Items]
Available for share repurchases under the share repurchase program	315.7		315.7
Additional Authorized Amount Under Share Repurchase Program	250
Shares repurchased	1.5
Aggregate purchase price	$ 51.9
Average purchase price per share	$ 33.67

- Definition

The remaining repurchase amount for share repurchases under the share repurchase program approved by the Board of Directors.

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- Definition

The number of shares repurchased under the share repurchase program authorized by the Board of Directors.

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- Definition

The total cost of common stock repurchased under the share repurchase program authorized by the Board of Directors divided by the number of shares repurchased.

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- Definition

The cost of common stock repurchased under the share repurchase program authorized by the Board of Directors.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

The amount authorized by an entity's Board of Directors under a stock repurchase plan.

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