Equity Compensation Plans (Narrative) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of shares available for grant (shares)	26
Weighted average fair value per option granted	$ 29.06	$ 37.42	$ 33.09
Stock option expense reduced operating earnings	$ 55	$ 57	$ 53
Stock option expense earnings per share	$ 0.15	$ 0.15	$ 0.11
Total intrinsic value of options exercised	$ 244	$ 147	$ 215
Stock Options
Awards vesting period	3 years
Awards expiration period	10 years
Unrecognized compensation cost related to stock options	$ 70
Recognition period for unrecognized compensation cost for restricted stock	1 year 9 months 18 days
Stock Options \| Vesting After Two years
Percentage of stock options vesting in a period of one year	50.00%
Stock Options \| Vesting In Third Year
Percentage of stock options vesting in a period of one year	50.00%
Restricted Stock and Restricted Stock Units (RSUs)
Awards vesting period	3 years
Stock option expense reduced operating earnings	$ 79	$ 83	$ 70
Stock option expense earnings per share	$ 0.21	$ 0.22	$ 0.15
Unrecognized compensation cost related to stock options	$ 53
Recognition period for unrecognized compensation cost for restricted stock	1 year 7 months 6 days
Fair value of vesting shares	$ 88	$ 242	$ 200

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

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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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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Percentage of vesting of award under share-based payment arrangement.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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