Management Stock Plans - Compensation Costs, Tax Benefit and Unrecognized Compensation Costs (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Compensation costs	$ 89	$ 77	$ 66
Tax benefit	23	20	26
Unrecognized compensation costs	$ 129	$ 110	$ 111
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition	1 year 4 months 24 days

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Amount of cost capitalized for award under share-based payment arrangement.

+ References

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

+ References

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

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