Stock-Based Compensation (Stock Option Activity) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015
Number of Options
Options outstanding at January 1, 2015	444,278
Exercised	(150,317)
Forfeited or expired	(3,979)
Options outstanding and exercisable at March 31, 2015	289,982
Options exercisable	289,982
Weighted Average Exercise Price
Options outstanding at January 1, 2015	$ 43.56
Exercised	$ 45.37
Forfeited or expired	$ 44.72
Options outstanding and exercisable at March 31, 2015	$ 42.61
Weighted Average Exercise Price - Options exercisable	$ 42.61
Aggregate Intrinsic Value - Options outstanding	$ 12
Aggregate Intrinsic Value - Options exercisable	$ 12

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.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 10

-Section 50

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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.

+ References

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- Definition

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.

+ References

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

+ References

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

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- Definition

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

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- Definition

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

+ References

No definition available.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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No definition available.

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Number of share options (or share units) exercised during the current period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

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