Fair Value Measurements - Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	$ 191	$ 127
Gross Amounts of Derivative Assets Presented in the Consolidated Balance Sheet	170	296
Gross Amounts of Derivative Liabilities Presented in the Consolidated Balance Sheet	156	69
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	117	272
Gross Amounts of Derivative Liabilities Presented in the Consolidated Balance Sheet	155	68
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	53	24
Gross Amounts of Derivative Liabilities Presented in the Consolidated Balance Sheet	1	1
Fair value on a recurring basis | Foreign government agency securities
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	10	10
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	36	12
Fair value on a recurring basis | Certificates of deposit/time deposits
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	46	26
Fair value on a recurring basis | Asset-backed securities Automobile loan related
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	44	26
Fair value on a recurring basis | Asset-backed securities Credit card related
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	19	10
Fair value on a recurring basis | Asset-backed securities Equipment lease related
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	1	2
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	19
Fair value on a recurring basis | U.S. municipal securities
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	18	12
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	117	272
Gross Amounts of Derivative Liabilities Presented in the Consolidated Balance Sheet	155	68
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	53	24
Gross Amounts of Derivative Liabilities Presented in the Consolidated Balance Sheet	1	1
Fair value on a recurring basis | Level 2 | Foreign government agency securities
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	10	10
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	36	12
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	46	26
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	44	26
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	19	10
Fair value on a recurring basis | Level 2 | Asset-backed securities Equipment lease related
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	1	2
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	19
Fair value on a recurring basis | Level 3 | U.S. municipal securities
Assets and Liabilities Measured on Recurring Basis
Available-for-sale marketable securities	$ 18	$ 12