v2.4.0.6
Fair value measurement (Details) (USD $)
In Millions, unless otherwise specified
Dec. 31, 2012
Dec. 31, 2011
Assets:    
Total available-for-sale investments $ 23,745 $ 20,003
Fair Value, Measurements, Recurring [Member]
    
Derivative Assets:    
Interest rate swap contracts   377
Total assets 23,856 20,552
Derivative Liabilities:    
Contingent consideration obligations in connection with a business combination 221 190
Total liabilities 286 264
Fair Value, Measurements, Recurring [Member] | Foreign currency contracts [Member]
    
Derivative Assets:    
Foreign currency contracts 46 172
Derivative Liabilities:    
Foreign currency contracts 59 48
Fair Value, Measurements, Recurring [Member] | Cross currency swap contracts [Member]
    
Derivative Assets:    
Foreign currency contracts 65  
Derivative Liabilities:    
Foreign currency contracts 6 26
Fair Value, Measurements, Recurring [Member] | U.S. Treasury securities [Member]
    
Assets:    
Total available-for-sale investments 4,458 3,946
Fair Value, Measurements, Recurring [Member] | Other government-related debt securities - U.S. [Member]
    
Assets:    
Total available-for-sale investments 1,030 1,571
Fair Value, Measurements, Recurring [Member] | Other government-related debt securities - Foreign and other [Member]
    
Assets:    
Total available-for-sale investments 1,608 450
Fair Value, Measurements, Recurring [Member] | Corporate debt securities - Financial [Member]
    
Assets:    
Total available-for-sale investments 3,361 2,508
Fair Value, Measurements, Recurring [Member] | Corporate debt securities - Industrial [Member]
    
Assets:    
Total available-for-sale investments 4,380 3,146
Fair Value, Measurements, Recurring [Member] | Corporate debt securities - Other [Member]
    
Assets:    
Total available-for-sale investments 452 289
Fair Value, Measurements, Recurring [Member] | Residential mortgage-backed securities [Member]
    
Assets:    
Total available-for-sale investments 1,829 518
Fair Value, Measurements, Recurring [Member] | Other mortgage- and asset-backed securities [Member]
    
Assets:    
Total available-for-sale investments 1,767 1,267
Fair Value, Measurements, Recurring [Member] | Money market mutual funds [Member]
    
Assets:    
Total available-for-sale investments 2,620 6,266
Fair Value, Measurements, Recurring [Member] | Other short-term interest-bearing securities [Member]
    
Assets:    
Total available-for-sale investments 2,186  
Fair Value, Measurements, Recurring [Member] | Equity securities [Member]
    
Assets:    
Total available-for-sale investments 54 42
Fair Value, Measurements, Recurring [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
    
Derivative Assets:    
Interest rate swap contracts   0
Total assets 7,132 10,254
Derivative Liabilities:    
Contingent consideration obligations in connection with a business combination 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 4,458 3,946
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 2,620 6,266
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  
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 54 42
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member]
    
Derivative Assets:    
Interest rate swap contracts   377
Total assets 16,724 10,298
Derivative Liabilities:    
Contingent consideration obligations in connection with a business combination 0 0
Total liabilities 65 74
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Foreign currency contracts [Member]
    
Derivative Assets:    
Foreign currency contracts 46 172
Derivative Liabilities:    
Foreign currency contracts 59 48
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Cross currency swap contracts [Member]
    
Derivative Assets:    
Foreign currency contracts 65  
Derivative Liabilities:    
Foreign currency contracts 6 26
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 1,030 1,571
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 1,608 450
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Corporate debt securities - Financial [Member]
    
Assets:    
Total available-for-sale investments 3,361 2,508
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Corporate debt securities - Industrial [Member]
    
Assets:    
Total available-for-sale investments 4,380 3,146
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Corporate debt securities - Other [Member]
    
Assets:    
Total available-for-sale investments 452 289
Fair Value, Measurements, Recurring [Member] | Significant other observable inputs (Level 2) [Member] | Residential mortgage-backed securities [Member]
    
Assets:    
Total available-for-sale investments 1,829 518
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 1,767 1,267
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 2,186  
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     
Total assets    0
Derivative Liabilities:    
Contingent consideration obligations in connection with a business combination 221 190
Total liabilities 221 190
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  
Fair Value, Measurements, Recurring [Member] | Significant unobservable inputs (Level 3) [Member] | Equity securities [Member]
    
Assets:    
Total available-for-sale investments $ 0 $ 0