XML 115 R80.htm IDEA: XBRL DOCUMENT v3.8.0.1
Retirement Benefits (Details 11) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Defined Contribution Plans Disclosure (Amounts in paragraphs)      
Employer match for contributions by plan participant 7.00%    
Defined Contribution Plan, Employer Discretionary Contribution Amount $ 344 $ 311 $ 291
Pension and post-retirement benefits disclosures (Amounts in paragraphs)      
Accumulated benefit obligation for all defined benefit pension plans 31,600 30,100  
OPEB contributions      
Defined Contribution Plans Disclosure (Amounts in paragraphs)      
Expected 2017 employer contributions 43    
Information About Plan Assets (Amounts in paragraphs) [Abstract]      
Defined Benefit Plan, Plan Assets, Contributions by Employer 45 83  
Pension Benefits      
Defined Contribution Plans Disclosure (Amounts in paragraphs)      
Expected 2017 employer contributions 87    
Information About Plan Assets (Amounts in paragraphs) [Abstract]      
Defined Benefit Plan, Plan Assets, Contributions by Employer 596 81  
Pension Benefits | Voluntary Contributions [Member]      
Information About Plan Assets (Amounts in paragraphs) [Abstract]      
Defined Benefit Plan, Plan Assets, Contributions by Employer 500    
OpportunisticFunds      
Information About Plan Assets (Amounts in paragraphs) [Abstract]      
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments 768 638  
Private Equity Funds [Member]      
Information About Plan Assets (Amounts in paragraphs) [Abstract]      
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments $ 1,400 1,300  
Average investment term, alternative investments 10 years    
Real Estate Funds      
Information About Plan Assets (Amounts in paragraphs) [Abstract]      
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments $ 71 72  
Average investment term, alternative investments 10 years    
Hedge Funds      
Information About Plan Assets (Amounts in paragraphs) [Abstract]      
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments $ 0 0  
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency quarterly    
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period 90 days    
Fixed Income Funds      
Information About Plan Assets (Amounts in paragraphs) [Abstract]      
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Unfunded Commitments $ 0 $ 0  
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency daily, monthly or quarterly    
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period 30 days    
U.S. Equity Securities [Member]      
Information About Plan Assets (Amounts in paragraphs) [Abstract]      
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency Monthly    
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period 30 days    
International Equity Securities [Member]      
Information About Plan Assets (Amounts in paragraphs) [Abstract]      
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Frequency Monthly    
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period 30 days    
SavingsPlan      
Defined Contribution Plans Disclosure (Amounts in paragraphs)      
Employer match for contributions by plan participant 4.00%    
Minimum | OpportunisticFunds      
Information About Plan Assets (Amounts in paragraphs) [Abstract]      
Average investment term, alternative investments 5 years    
Maximum | OpportunisticFunds      
Information About Plan Assets (Amounts in paragraphs) [Abstract]      
Average investment term, alternative investments 10 years