Annual report pursuant to Section 13 and 15(d)

Employee Benefit Plans - Fair Value Measurements (Details)

v3.10.0.1
Employee Benefit Plans - Fair Value Measurements (Details) - USD ($)
$ in Millions
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets $ 23,475 $ 25,675    
Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 11,538 13,332    
Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 10,368 11,251    
Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,569 1,092 $ 1,029 $ 1,037
Money market and interest-bearing cash        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,530 2,190    
Money market and interest-bearing cash | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,530 2,190    
Money market and interest-bearing cash | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Money market and interest-bearing cash | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Cash and cash equivalent commingled/mutual funds        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 644 1,004    
Cash and cash equivalent commingled/mutual funds | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Cash and cash equivalent commingled/mutual funds | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 644 1,004    
Cash and cash equivalent commingled/mutual funds | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
U.S. government and agency securities        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 4,451 4,194    
U.S. government and agency securities | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 3,637 3,331    
U.S. government and agency securities | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 805 854    
U.S. government and agency securities | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 9 9 10 11
Corporate debt securities        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 2,852 2,417    
Corporate debt securities | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Corporate debt securities | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 2,852 2,417    
Corporate debt securities | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Asset-backed securities        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 2,119 1,832    
Asset-backed securities | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Asset-backed securities | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 2,119 1,832    
Asset-backed securities | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Non-U.S. debt securities        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,500 1,591    
Non-U.S. debt securities | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 539 693    
Non-U.S. debt securities | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 961 898    
Non-U.S. debt securities | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Fixed income commingled/mutual funds        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 2,110 2,451    
Fixed income commingled/mutual funds | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 933 775    
Fixed income commingled/mutual funds | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,177 1,676    
Fixed income commingled/mutual funds | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Common and preferred equity securities        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 4,414 5,833    
Common and preferred equity securities | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 4,414 5,833    
Common and preferred equity securities | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Common and preferred equity securities | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Equity commingled/mutual funds        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,563 2,024    
Equity commingled/mutual funds | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 288 271    
Equity commingled/mutual funds | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,275 1,753    
Equity commingled/mutual funds | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Public real estate investment trusts        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 104 138    
Public real estate investment trusts | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 104 138    
Public real estate investment trusts | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Public real estate investment trusts | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Private real estate        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 5 93    
Private real estate | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Private real estate | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Private real estate | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 5 93 150 144
Real estate commingled/mutual funds        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 898 844    
Real estate commingled/mutual funds | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Real estate commingled/mutual funds | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 13 13    
Real estate commingled/mutual funds | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 885 831 748 731
Limited partnerships        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 240 240    
Limited partnerships | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0    
Limited partnerships | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 158 155    
Limited partnerships | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 82 85 38 49
Other investments        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,045 824    
Other investments | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 93 101    
Other investments | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 364 649    
Other investments | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 588 74 $ 83 $ 102
Commodity and Balanced Funds        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 305 451    
Insurance Annuity Contracts        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 562 50    
Other Various Investments        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets $ 178 $ 323