Supplemental Equity and Comprehensive Income Information (Details 2) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss)    
Balance at Beginning of Period $ (6,289) $ (3,913)
Other comprehensive income (loss), before tax:    
Amounts before reclassification 116 16
Amounts reclassified out 97 85
Total other comprehensive income (loss), before tax 213 101
Tax effect (245) (29)
Total other comprehensive income (loss), net of tax (32) 72
Balance at End of Period (6,321) (3,841)
Cumulative Translation Adjustment    
Accumulated Other Comprehensive Income (Loss)    
Balance at Beginning of Period (1,095) (188)
Other comprehensive income (loss), before tax:    
Amounts before reclassification (44) 5
Amounts reclassified out 0 0
Total other comprehensive income (loss), before tax (44) 5
Tax effect (149) 3
Total other comprehensive income (loss), net of tax (193) 8
Balance at End of Period (1,288) (180)
Gains (losses) associated with defined benefit pension and postretirement plans amortization    
Accumulated Other Comprehensive Income (Loss)    
Balance at Beginning of Period (5,293) (3,715)
Other comprehensive income (loss), before tax:    
Amounts before reclassification 24 0
Amounts reclassified out 124 91
Total other comprehensive income (loss), before tax 148 91
Tax effect (57) (30)
Total other comprehensive income (loss), net of tax 91 61
Balance at End of Period (5,202) (3,654)
Debt and equity security gains (losses)    
Accumulated Other Comprehensive Income (Loss)    
Balance at Beginning of Period 0 (2)
Other comprehensive income (loss), before tax:    
Amounts before reclassification 0 2
Amounts reclassified out 0 0
Total other comprehensive income (loss), before tax 0 2
Tax effect 0 (1)
Total other comprehensive income (loss), net of tax 0 1
Balance at End of Period 0 (1)
Cash flow hedging instruments gains (losses)    
Accumulated Other Comprehensive Income (Loss)    
Balance at Beginning of Period 99 (8)
Other comprehensive income (loss), before tax:    
Amounts before reclassification 136 9
Amounts reclassified out (27) (6)
Total other comprehensive income (loss), before tax 109 3
Tax effect (39) (1)
Total other comprehensive income (loss), net of tax 70 2
Balance at End of Period $ 169 $ (6)