Fair Value Measurement of Assets and Liabilities - Financial Assets and Liabilities Measured at Fair Value, Recurring and Nonrecurring (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Assets:
Derivatives	$ 139	$ 84
Liabilities:
Derivatives	10
Short-term Investments
Assets:
Investments	2,914	3,730
Long-term Investments
Assets:
Investments	3,449	5,552
Corporate debt securities | Short-term Investments
Assets:
Investments	2,039	2,519
Corporate debt securities | Long-term Investments
Assets:
Investments	3,449	5,319
Equity instruments | Short-term Investments
Assets:
Investments	740	1,037
Recurring
Assets:
Cash and cash equivalents	2,387	4,105
Total financial assets	8,889	13,471
Recurring | Short-term Investments
Assets:
Investments	2,914	3,730
Recurring | Long-term Investments
Assets:
Investments	3,449	5,552
Recurring | Restricted cash | Short-term Investments
Assets:
Investments	30	19
Recurring | Corporate debt securities | Short-term Investments
Assets:
Investments	2,039	2,519
Recurring | Corporate debt securities | Long-term Investments
Assets:
Investments	3,449	5,319
Recurring | Government and agency securities | Short-term Investments
Assets:
Investments	55	3
Recurring | Government and agency securities | Long-term Investments
Assets:
Investments		233
Recurring | Time deposits | Short-term Investments
Assets:
Investments	50	152
Recurring | Equity instruments | Short-term Investments
Assets:
Investments	740	1,037
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Cash and cash equivalents	1,954	1,694
Total financial assets	2,724	2,750
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term Investments
Assets:
Investments	770	1,056
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Long-term Investments
Assets:
Investments	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Restricted cash | Short-term Investments
Assets:
Investments	30	19
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate debt securities | Short-term Investments
Assets:
Investments	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate debt securities | Long-term Investments
Assets:
Investments	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Government and agency securities | Short-term Investments
Assets:
Investments	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Government and agency securities | Long-term Investments
Assets:
Investments		0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Time deposits | Short-term Investments
Assets:
Investments	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity instruments | Short-term Investments
Assets:
Investments	740	1,037
Recurring | Significant Other Observable Inputs (Level 2)
Assets:
Cash and cash equivalents	433	2,411
Total financial assets	6,165	10,721
Recurring | Significant Other Observable Inputs (Level 2) | Short-term Investments
Assets:
Investments	2,144	2,674
Recurring | Significant Other Observable Inputs (Level 2) | Long-term Investments
Assets:
Investments	3,449	5,552
Recurring | Significant Other Observable Inputs (Level 2) | Restricted cash | Short-term Investments
Assets:
Investments	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt securities | Short-term Investments
Assets:
Investments	2,039	2,519
Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt securities | Long-term Investments
Assets:
Investments	3,449	5,319
Recurring | Significant Other Observable Inputs (Level 2) | Government and agency securities | Short-term Investments
Assets:
Investments	55	3
Recurring | Significant Other Observable Inputs (Level 2) | Government and agency securities | Long-term Investments
Assets:
Investments		233
Recurring | Significant Other Observable Inputs (Level 2) | Time deposits | Short-term Investments
Assets:
Investments	50	152
Recurring | Significant Other Observable Inputs (Level 2) | Equity instruments | Short-term Investments
Assets:
Investments	0	0
Recurring | Foreign Exchange Contract | Other Current Assets
Assets:
Derivatives	139	84
Recurring | Foreign Exchange Contract | Other Current Liabilities
Liabilities:
Derivatives	32	20
Recurring | Foreign Exchange Contract | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Current Assets
Assets:
Derivatives	0	0
Recurring | Foreign Exchange Contract | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Current Liabilities
Liabilities:
Derivatives	0	0
Recurring | Foreign Exchange Contract | Significant Other Observable Inputs (Level 2) | Other Current Assets
Assets:
Derivatives	139	84
Recurring | Foreign Exchange Contract | Significant Other Observable Inputs (Level 2) | Other Current Liabilities
Liabilities:
Derivatives	$ 32	$ 20