Annual report pursuant to Section 13 and 15(d)

Employee Benefit Plans - Fair Value Measurements (Details)

v3.20.4
Employee Benefit Plans - Fair Value Measurements (Details) - USD ($)
$ in Millions
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets $ 27,786 $ 25,836    
Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 12,865 12,285    
Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 13,197 11,890    
Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,724 1,661 $ 1,569 $ 1,092
Money market and interest-bearing cash        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,380 1,426    
Money market and interest-bearing cash | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,380 1,426    
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 383 250    
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 383 250    
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 5,835 5,301    
U.S. government and agency securities | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 4,590 4,403    
U.S. government and agency securities | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,238 890    
U.S. government and agency securities | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 7 8 9 9
Corporate debt securities        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 5,021 3,676    
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 5,021 3,676    
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 1,967 2,684    
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 1,967 2,684    
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 2,143 1,763    
Non-U.S. debt securities | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,021 748    
Non-U.S. debt securities | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,122 1,015    
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 2,543 2,243    
Fixed income commingled/mutual funds | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,224 804    
Fixed income commingled/mutual funds | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,319 1,439    
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 4,438 4,655    
Common and preferred equity securities | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 4,438 4,655    
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 1,676 1,502    
Equity commingled/mutual funds | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 134 147    
Equity commingled/mutual funds | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,542 1,355    
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 73 91    
Public real estate investment trusts | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 73 91    
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 | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets   0 5 93
Real estate commingled/mutual funds        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 963 945    
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 20 18    
Real estate commingled/mutual funds | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 943 927 885 831
Limited partnerships        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 267 263    
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 184 173    
Limited partnerships | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 83 90 82 85
Other investments        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,097 1,037    
Other investments | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 5 11    
Other investments | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 401 390    
Other investments | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 691 636 $ 588 $ 74
Commodity and Balanced Funds        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 246 233    
Insurance Annuity Contracts        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 664 614    
Other Various Investments        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets $ 187 $ 190