Benefit Plans (Stock Option and SARs Activity) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock options and Stock appreciation rights awards outstanding at January 1	1,158,700
Weighted-average exercise price per award outstanding at January 1	$ 25.93
Number of awards granted
Weighted-average exercise price on awards granted
Number of awards exercised	(117,950)
Weighted-average exercise price on awards exercised	$ 21.19
Number of awards forfeited, canceled or expired	(4,100)
Weighted-average exercise price on awards forfeited, canceled or expired	$ 30.66
Stock options and Stock appreciation rights awards outstanding at December 31	1,036,650
Weighted-average exercise price per award outstanding at December 31	$ 26.45
Aggregate intrinsic value on awards outstanding	$ 17
Weighted-average remaining contractual term on awards outstanding	4 years 1 month 28 days
Number of awards outstanding, fully vested and expected to vest	1,032,849
Weighted-average exercise price per award outstanding, fully vested and expected to vest	$ 26.45
Aggregate intrinsic value on awards outstanding, fully vested and expected to vest	17
Weighted-average remaining contractual term on awards outstanding, fully vested and expected to vest	4 years 1 month 25 days
Number of awards outstanding, exercisable	936,650
Weighted-average exercise price, awards outstanding, exercisable	$ 26.42
Aggregate intrinsic value, awards outstanding, exercisable	$ 15
Weighted-average remaining contractual term, awards outstanding, exercisable	3 years 10 months 15 days

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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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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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Weighted average price of options that were either forfeited or expired.

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Net number of share options (or share units) granted during the period.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount by which the current fair value of the underlying stock exceeds the exercise price of fully vested and expected to vest options outstanding.

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As of the balance sheet date, the number of shares into which fully vested and expected to vest stock options outstanding can be converted under the option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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