Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Earnings Per Share [Line Items]
Net income attributable to common stockholders - basic	$ 2,866	$ 1,117	$ 4,819	$ 2,062
Less: earnings adjustment for dilutive stock compensation rights	(1)	(4)	(2)	(1)
Net income attributable to common stockholders – diluted	$ 2,865	$ 1,113	$ 4,817	$ 2,061
Weighted-average common shares outstanding - basic	1,548	1,596	1,547	1,606
Dilutive effect of warrants and awards under stock incentive plans	33	64	33	67
Weighted-average common shares outstanding - diluted	1,581	1,660	1,580	1,673
Diluted earnings per common share	$ 1.81	$ 0.67	$ 3.05	$ 1.23
Stock options [Member]
Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted EPS (shares)	26		26
Warrants [Member]
Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of diluted EPS (shares)		46		46

Amount of increase (decrease) to net income used for calculating diluted earnings per share (EPS), resulting from the assumed exercise of stock options or restrictive stock units (RSUs).

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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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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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 call options and warrants 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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Net Income or Loss Available to Common Stockholders plus adjustments resulting from the assumption that dilutive convertible securities were converted, options or warrants were exercised, or that other shares were issued upon the satisfaction of certain conditions.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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