Annual report pursuant to Section 13 and 15(d)

Employee Benefit Plans - Narrative (Details)

v3.8.0.1
Employee Benefit Plans - Narrative (Details) - USD ($)
shares in Millions
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets $ 25,675,000,000 $ 23,772,000,000  
Increase (decrease) from change in weighted average discount rates 1,100,000,000 (1,300,000,000)  
Defined Contribution Plan:      
Cost recognized $ 1,000,000,000 $ 1,000,000,000 $ 1,000,000,000
Number of common stock shares held in plan (in shares) 218 224  
Dividend payments to the plan $ 86,000,000 $ 60,000,000 48,000,000
Interest Rate Swap      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 156,000,000 257,000,000  
Participant Loans      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 20,000,000 36,000,000  
Commodity and Balanced Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 451,000,000 369,000,000  
Other Various Investments      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 197,000,000 168,000,000  
U.S. | Pension Plan | Qualified      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 19,708,000,000 18,239,000,000 17,962,000,000
Company contributions $ 0 0  
Percentage of prior years market gains (losses) recognized at next measurement date 60.00%    
Percentage of prior years market gains (losses) recognized equally over four year period 40.00%    
Effect of 25 basis point decline in discount rate on net periodic benefit cost $ 6,000,000    
Effect of 25 basis point decline in expected return on plan assets on net periodic benefit cost 45,000,000    
Plan assets recognized in the next fiscal year with respect to decline in discount rate 6,000,000    
Plan assets recognized in the next fiscal year with respect to decline in expected return 47,000,000    
U.S. | Pension Plan | Qualified | Equity securities      
Defined Benefit Plan Disclosure [Line Items]      
Amount of employer and related party securities included in plan assets $ 261,000,000 $ 203,000,000  
Actual plan asset allocations 1.33% 1.11%  
U.S. | Other Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Company contributions $ 0 $ 0  
U.S. | Other Pension Plan | Nonqualified      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 2,724,000,000 2,744,000,000 2,805,000,000
Company contributions 98,000,000 104,000,000  
Estimated future employer contributions in next fiscal year 92,000,000    
U.S. | Postretirement Health and Life Plans      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 300,000,000 0 0
Company contributions 393,000,000 104,000,000  
Estimated future employer contributions in next fiscal year $ 19,000,000    
Percentage of unrecognized gain (loss) recognized during the period 50.00%    
Health care cost trend rate assumed for next fiscal year 7.00%    
Ultimate health care cost trend rate 5.00%    
Effect of 1% increase on service and interest cost components $ 1,000,000    
Effect of 1% increase on accumulated postretirement benefit obligation 26,000,000    
Effect of 1% decrease on service and interest cost components 1,000,000    
Effect of 1% decrease on accumulated postretirement benefit obligation 23,000,000    
Non-U.S. | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Fair value of plan assets 2,943,000,000 2,789,000,000 $ 2,738,000,000
Company contributions 23,000,000 $ 48,000,000  
Estimated future employer contributions in next fiscal year $ 17,000,000