Employee Benefit Plans (Stock Based Compensation) (Narrative) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected Volatility, Minimum	18.80%	17.50%
Equity Awards Vested and Expected to Vest, Remaining Term	2 years 10 months 24 days
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	184,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	42,000
Expected Range Of Shares Awarded Annually Under Long Term Incentive Plan	1.0% to 1.5%
Share-based Payment Arrangement, Expense, Tax Benefit	$ 66	$ 42	$ 38
Proceeds from Stock Options Exercised	27	36	29
Share-based Payment Arrangement, Exercise of Option, Tax Benefit	75	59	100
Employee Service Share Based Compensation Tax Benefit Realized From Vesting Of Performance Share Units	36	13	12
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount	291
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Vested In Period Total Fair Value	$ 211	$ 149	$ 138
Stock Options/Stock Appreciation Rights SARS [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity Awards Vested and Expected to Vest, Awards	33,769
Equity Awards Vested and Expected to Vest, Average Intrinsic Value	$ 1,424
Equity Awards Vested and Expected to Vest, Remaining Term	5 years 10 months 24 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 20.81	$ 20.24	$ 17.22
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	$ 383	$ 283	$ 320
Performance Share Units/Other Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity Awards Vested and Expected to Vest, Awards	5,514
Equity Awards Vested and Expected to Vest, Average Intrinsic Value	$ 826
Equity Awards Vested and Expected to Vest, Remaining Term	2 years 1 month 6 days
Share Based Compensation Arrangement By Share Based Payment Award Options and Other Restricted Awards Exercised In Period Total Intrinsic Value	$ 188	$ 74	$ 49
Performance Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 117.87	$ 131.55	$ 111.00

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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Amount of tax benefit from exercise of option under share-based payment arrangement.

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Amount of cash inflow from exercise of option under share-based payment arrangement.

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The estimated measure of the minimum percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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Number of shares authorized for issuance under share-based payment arrangement.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted average remaining contractual term for fully vested and expected to vest exercisable or convertible options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Disclosure of the aggregate tax benefit realized from the vesting of performance share units during the annual period.

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Expected range of shares awarded on an annual basis under the long-term incentive plan. There is no annual award limit in the long-term incentive plan.

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The total fair value of share-based awards for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares, other instruments, or cash in accordance with the terms of the arrangement.

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Share Based Compensation Arrangement By Share Based Payment Award Options and Other Restricted Awards Exercised In Period Total Intrinsic Value

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