Severance and Leased Real Estate (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2019
Severance
Restructuring reserve [Roll Forward]
Balance at the beginning of the period	$ 87	$ 33
Accrued to expense	89	205
Payments, net	(87)	(151)
Balance at the end of the period	$ 89	$ 87
Real Estate Lease No Longer In Use \| Leased real estate
Severance and Leased Real Estate
Operating lease payments due			$ 110

Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

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Amount of cash payments made as the result of exit or disposal activities. Excludes payments associated with a discontinued operation or an asset retirement obligation.

+ References

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Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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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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Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.

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