Fair Value Measurements - Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	$ 76	$ 417
Gross Amounts of Derivative Assets Presented in the Consolidated Balance Sheet	227	146
Gross Amounts of Derivative Liabilities Presented in the Consolidated Balance Sheet	14	53
Fair value on a recurring basis \| Foreign currency forward/option contracts
Assets and Liabilities Measured on Recurring Basis
Gross Amounts of Derivative Assets Presented in the Consolidated Balance Sheet	207	127
Gross Amounts of Derivative Liabilities Presented in the Consolidated Balance Sheet	13	22
Fair value on a recurring basis \| Interest rate swap contracts
Assets and Liabilities Measured on Recurring Basis
Gross Amounts of Derivative Assets Presented in the Consolidated Balance Sheet	20	19
Gross Amounts of Derivative Liabilities Presented in the Consolidated Balance Sheet	1	31
Fair value on a recurring basis \| Commercial paper
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities		366
Fair value on a recurring basis \| Certificates of deposit/time deposits
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	27	10
Fair value on a recurring basis \| Asset-backed securities
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities		1
Fair value on a recurring basis \| U.S. municipal securities
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	49	40
Fair value on a recurring basis \| Investments
Assets and Liabilities Measured on Recurring Basis
Investments	22
Fair value on a recurring basis \| Level 1 \| Investments
Assets and Liabilities Measured on Recurring Basis
Investments	22
Fair value on a recurring basis \| Level 2 \| Foreign currency forward/option contracts
Assets and Liabilities Measured on Recurring Basis
Gross Amounts of Derivative Assets Presented in the Consolidated Balance Sheet	207	127
Gross Amounts of Derivative Liabilities Presented in the Consolidated Balance Sheet	13	22
Fair value on a recurring basis \| Level 2 \| Interest rate swap contracts
Assets and Liabilities Measured on Recurring Basis
Gross Amounts of Derivative Assets Presented in the Consolidated Balance Sheet	20	19
Gross Amounts of Derivative Liabilities Presented in the Consolidated Balance Sheet	1	31
Fair value on a recurring basis \| Level 2 \| Commercial paper
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities		366
Fair value on a recurring basis \| Level 2 \| Certificates of deposit/time deposits
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	27	10
Fair value on a recurring basis \| Level 2 \| Asset-backed securities
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities		1
Fair value on a recurring basis \| Level 3 \| U.S. municipal securities
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	$ 49	$ 40

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