Fair Value Measurements - Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	$ 603	$ 297
Gross Amounts of Derivative Assets Presented in the Consolidated Balance Sheet	77	259
Gross Amounts of Derivative Liabilities Presented in the Consolidated Balance Sheet	182	95
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	55	234
Gross Amounts of Derivative Liabilities Presented in the Consolidated Balance Sheet	179	94
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	22	25
Gross Amounts of Derivative Liabilities Presented in the Consolidated Balance Sheet	3	1
Fair value on a recurring basis | Corporate debt securities
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	10	10
Fair value on a recurring basis | Commercial paper
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	446	14
Fair value on a recurring basis | Certificates of deposit/time deposits
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	84	197
Fair value on a recurring basis | Asset-backed securities Automobile loan related
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	14	31
Fair value on a recurring basis | Asset-backed securities Credit card related
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	29	18
Fair value on a recurring basis | Asset-backed securities Other asset-backed securities
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities		7
Fair value on a recurring basis | U.S. municipal securities
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	20	20
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	55	234
Gross Amounts of Derivative Liabilities Presented in the Consolidated Balance Sheet	179	94
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	22	25
Gross Amounts of Derivative Liabilities Presented in the Consolidated Balance Sheet	3	1
Fair value on a recurring basis | Level 2 | Corporate debt securities
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	10	10
Fair value on a recurring basis | Level 2 | Commercial paper
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	446	14
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	84	197
Fair value on a recurring basis | Level 2 | Asset-backed securities Automobile loan related
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	14	31
Fair value on a recurring basis | Level 2 | Asset-backed securities Credit card related
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	29	18
Fair value on a recurring basis | Level 2 | Asset-backed securities Other asset-backed securities
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities		7
Fair value on a recurring basis | Level 3 | U.S. municipal securities
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	$ 20	$ 20