Supplemental Financial Information (Earnings Per Share) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2014	Mar. 31, 2013
Earnings Per Share [Abstract]
Numerator: Net income	$ 165	$ 191
Denominator for net income per share (basic)	584	570
Effect of dilutive securities:
Stock awards	6	15
Denominator for net income per share (diluted) (shares)	590	585
Net income per share (basic) (usd per share)	$ 0.28	$ 0.34
Net income per share (diluted) (usd per share)	$ 0.28	$ 0.33
Anti-dilutive common share equivalents (shares)	35	21

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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

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