Fair value measurement (Details) (USD $) | Mar. 31, 2015 | Dec. 31, 2014 | Mar. 31, 2014 | Dec. 31, 2013 |
In Millions, unless otherwise specified |
Assets: | | | | |
Total available-for-sale investments | $26,674 | $26,732 | | |
Fair Value, Measurements, Recurring [Member] | | | | |
Derivative Assets: | | | | |
Interest rate swap contracts | 109 | 46 | | |
Total assets | 27,462 | 27,170 | | |
Derivative Liabilities: | | | | |
Interest rate swap contracts | | 26 | | |
Contingent consideration obligations in connection with business combinations | 215 | 215 | | |
Total liabilities | 424 | 257 | | |
Fair Value, Measurements, Recurring [Member] | Foreign currency contracts [Member] | | | | |
Derivative Assets: | | | | |
Foreign currency contracts | 679 | 360 | | |
Derivative Liabilities: | | | | |
Foreign currency contracts | 12 | 4 | | |
Fair Value, Measurements, Recurring [Member] | Cross currency swap contracts [Member] | | | | |
Derivative Assets: | | | | |
Foreign currency contracts | | 32 | | |
Derivative Liabilities: | | | | |
Foreign currency contracts | 197 | 12 | | |
Fair Value, Measurements, Recurring [Member] | U.S. Treasury securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 3,284 | 3,646 | | |
Fair Value, Measurements, Recurring [Member] | Other government-related debt securities - U.S. [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 518 | 528 | | |
Fair Value, Measurements, Recurring [Member] | Other government-related debt securities - Foreign and other [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 1,725 | 1,569 | | |
Fair Value, Measurements, Recurring [Member] | Corporate debt securities - Financial [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 6,576 | 6,041 | | |
Fair Value, Measurements, Recurring [Member] | Corporate debt securities - Industrial [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 6,902 | 6,351 | | |
Fair Value, Measurements, Recurring [Member] | Corporate debt securities - Other [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 678 | 649 | | |
Fair Value, Measurements, Recurring [Member] | Residential mortgage-backed securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 1,604 | 1,702 | | |
Fair Value, Measurements, Recurring [Member] | Other mortgage- and asset-backed securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 1,674 | 1,796 | | |
Fair Value, Measurements, Recurring [Member] | Money market mutual funds [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 2,035 | 3,004 | | |
Fair Value, Measurements, Recurring [Member] | Other short-term interest-bearing securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 1,520 | 1,302 | | |
Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 158 | 144 | | |
Fair Value, Measurements, Recurring [Member] | Quoted prices in active markets for identical assets (Level 1) [Member] | | | | |
Derivative Assets: | | | | |
Interest rate swap contracts | 0 | 0 | | |
Total assets | 5,477 | 6,794 | | |
Derivative Liabilities: | | | | |
Interest rate swap contracts | | 0 | | |
Contingent consideration obligations in connection with business combinations | 0 | 0 | | |
Total liabilities | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Quoted prices in active markets for identical assets (Level 1) [Member] | Foreign currency contracts [Member] | | | | |
Derivative Assets: | | | | |
Foreign currency contracts | 0 | 0 | | |
Derivative Liabilities: | | | | |
Foreign currency contracts | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Quoted prices in active markets for identical assets (Level 1) [Member] | Cross currency swap contracts [Member] | | | | |
Derivative Assets: | | | | |
Foreign currency contracts | | 0 | | |
Derivative Liabilities: | | | | |
Foreign currency contracts | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Quoted prices in active markets for identical assets (Level 1) [Member] | U.S. Treasury securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 3,284 | 3,646 | | |
Fair Value, Measurements, Recurring [Member] | Quoted prices in active markets for identical assets (Level 1) [Member] | Other government-related debt securities - U.S. [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Quoted prices in active markets for identical assets (Level 1) [Member] | Other government-related debt securities - Foreign and other [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Quoted prices in active markets for identical assets (Level 1) [Member] | Corporate debt securities - Financial [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Quoted prices in active markets for identical assets (Level 1) [Member] | Corporate debt securities - Industrial [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Quoted prices in active markets for identical assets (Level 1) [Member] | Corporate debt securities - Other [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Quoted prices in active markets for identical assets (Level 1) [Member] | Residential mortgage-backed securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Quoted prices in active markets for identical assets (Level 1) [Member] | Other mortgage- and asset-backed securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Quoted prices in active markets for identical assets (Level 1) [Member] | Money market mutual funds [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 2,035 | 3,004 | | |
Fair Value, Measurements, Recurring [Member] | Quoted prices in active markets for identical assets (Level 1) [Member] | Other short-term interest-bearing securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Quoted prices in active markets for identical assets (Level 1) [Member] | Equity securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 158 | 144 | | |
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | | | | |
Derivative Assets: | | | | |
Interest rate swap contracts | 109 | 46 | | |
Total assets | 21,985 | 20,376 | | |
Derivative Liabilities: | | | | |
Interest rate swap contracts | | 26 | | |
Contingent consideration obligations in connection with business combinations | 0 | 0 | | |
Total liabilities | 209 | 42 | | |
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Foreign currency contracts [Member] | | | | |
Derivative Assets: | | | | |
Foreign currency contracts | 679 | 360 | | |
Derivative Liabilities: | | | | |
Foreign currency contracts | 12 | 4 | | |
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Cross currency swap contracts [Member] | | | | |
Derivative Assets: | | | | |
Foreign currency contracts | | 32 | | |
Derivative Liabilities: | | | | |
Foreign currency contracts | 197 | 12 | | |
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | U.S. Treasury securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Other government-related debt securities - U.S. [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 518 | 528 | | |
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Other government-related debt securities - Foreign and other [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 1,725 | 1,569 | | |
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Corporate debt securities - Financial [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 6,576 | 6,041 | | |
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Corporate debt securities - Industrial [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 6,902 | 6,351 | | |
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Corporate debt securities - Other [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 678 | 649 | | |
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Residential mortgage-backed securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 1,604 | 1,702 | | |
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Other mortgage- and asset-backed securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 1,674 | 1,796 | | |
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Money market mutual funds [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Other short-term interest-bearing securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 1,520 | 1,302 | | |
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Equity securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) [Member] | | | | |
Derivative Assets: | | | | |
Interest rate swap contracts | 0 | 0 | | |
Total assets | 0 | 0 | | |
Derivative Liabilities: | | | | |
Interest rate swap contracts | | 0 | | |
Contingent consideration obligations in connection with business combinations | 215 | 215 | 596 | 595 |
Total liabilities | 215 | 215 | | |
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) [Member] | Foreign currency contracts [Member] | | | | |
Derivative Assets: | | | | |
Foreign currency contracts | 0 | 0 | | |
Derivative Liabilities: | | | | |
Foreign currency contracts | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) [Member] | Cross currency swap contracts [Member] | | | | |
Derivative Assets: | | | | |
Foreign currency contracts | | 0 | | |
Derivative Liabilities: | | | | |
Foreign currency contracts | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) [Member] | U.S. Treasury securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) [Member] | Other government-related debt securities - U.S. [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) [Member] | Other government-related debt securities - Foreign and other [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) [Member] | Corporate debt securities - Financial [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) [Member] | Corporate debt securities - Industrial [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) [Member] | Corporate debt securities - Other [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) [Member] | Residential mortgage-backed securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) [Member] | Other mortgage- and asset-backed securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) [Member] | Money market mutual funds [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) [Member] | Other short-term interest-bearing securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | 0 | 0 | | |
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) [Member] | Equity securities [Member] | | | | |
Assets: | | | | |
Total available-for-sale investments | $0 | $0 | | |