Income Taxes - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Tax Disclosure [Abstract]
Effective income tax rate	14.90%	34.30%	20.10%	31.00%
Cash paid for income taxes, net of refunds			$ 567	$ 413
Change in cash paid for income taxes, net of refunds			154
Provisional estimate of the benefit of the 2017 tax act due to the one-time transition tax			5
Provisional estimate of the impact of the 2017 tax act due to deemed repatriation transition tax			740
Tax expense relating to remitted accumulated earnings of non-U.S. subsidiaries			$ 27

Increase (Decrease) in Income Taxes Paid, Net

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- Definition

Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Transition Tax For Accumulated Foreign Earnings, Provisional Income Tax Expense

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Tax Cuts And Jobs Act Of 2017, Incomplete Accounting, Transition Tax For Accumulated Foreign and State Earnings, Provisional Income Tax Expense

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- Definition

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to repatriation of foreign earnings.

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The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

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