Computation of EPS (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Computation of EPS
Net income available to common shareholders	$ 2,003	$ 1,562	$ 1,916
Weighted average number of shares outstanding, basic	718,140	703,042	698,739
Effect of dilutive outstanding equity-based awards	10,232	11,321	10,138
Weighted average number of shares outstanding, diluted	728,372	714,363	708,877
EPS basic	$ 2.79us-gaap_EarningsPerShareBasic	$ 2.22us-gaap_EarningsPerShareBasic	$ 2.74us-gaap_EarningsPerShareBasic
EPS diluted	$ 2.75us-gaap_EarningsPerShareDiluted	$ 2.19us-gaap_EarningsPerShareDiluted	$ 2.70us-gaap_EarningsPerShareDiluted
Anti-dilutive awards	14,333	28,456	36,589

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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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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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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