Stock-Based Compensation Plans (Summary Of Stock Option Activity) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2012 1992 Plan [Member]	Dec. 31, 2011 1992 Plan [Member]	Dec. 31, 2010 1992 Plan [Member]	Dec. 31, 2012 Director Plan [Member]	Dec. 31, 2011 Director Plan [Member]	Dec. 31, 2010 Director Plan [Member]	Dec. 31, 2009 Director Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Outstanding	5,905	307,129	608,564	100,000		100,000	100,000
Options exercised	(5,905)	(300,024)	(300,475)	(30,000)
Number of Shares, Forfeited		(1,200)	(960)
Number of Shares, Outstanding		5,905	307,129	70,000		100,000	100,000
Number of Options, Exercisable		5,905	307,129	70,000	100,000	100,000
Weighted Average Exercise Per Share, Outstanding	$ 15.37	$ 9.84	$ 9.75	$ 17.25		$ 17.25	$ 17.25
Weighted Average Exercise Per Share, Options exercised	$ 15.37	$ 9.74	$ 9.66	$ 17.25
Weighted Average Exercise Per Share, Options forfeited		$ 8.48	$ 7.45
Weighted Average Exercise Per Share, Outstanding		$ 15.37	$ 9.84	$ 17.25		$ 17.25	$ 17.25
Weighted Average Exercise Per Share, Exercisable		$ 15.37	$ 9.84	$ 17.25	$ 17.25	$ 17.25
Aggregate Intrinsic Value, Options exercised	$ 0.5	$ 15.8	$ 10.0	$ 2.5
Aggregate Intrinsic Value, Exercisable		$ 0.4	$ 16.3	$ 5.9	$ 6.5	$ 4.6

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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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