Annual report pursuant to Section 13 and 15(d)

Employee Benefit Plans - Fair Value Measurements (Details)

v3.3.1.900
Employee Benefit Plans - Fair Value Measurements (Details) - USD ($)
$ in Millions
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets $ 23,505 $ 24,133    
Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 13,843 13,315    
Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 8,625 9,856    
Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,037 962 $ 879 $ 817
Money market and interest-bearing cash        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 3,061 3,814    
Money market and interest-bearing cash | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 3,061 3,814    
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 4 4    
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 4 4    
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 3,615 4,166    
U.S. government and agency securities | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 2,723 2,004    
U.S. government and agency securities | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 881 2,151    
U.S. government and agency securities | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 11 11 12 13
Corporate debt securities        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,795 1,454    
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 1,795 1,454    
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 1,939 1,930    
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 1,939 1,930    
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 1,294 1,114    
Non-U.S. debt securities | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 632 627    
Non-U.S. debt securities | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 662 487    
Non-U.S. debt securities | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 0 6 10
Fixed income commingled/mutual funds        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,972 1,498    
Fixed income commingled/mutual funds | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 551 101    
Fixed income commingled/mutual funds | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,421 1,397    
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 6,735 6,628    
Common and preferred equity securities | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 6,735 6,628    
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 1,506 1,833    
Equity commingled/mutual funds | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 3 16    
Equity commingled/mutual funds | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 1,503 1,817    
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 138 124    
Public real estate investment trusts | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 138 124    
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 144 127    
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 144 127 119 110
Real estate commingled/mutual funds        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 743 636    
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 12 4    
Real estate commingled/mutual funds | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 731 632 462 324
Limited partnerships        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 170 187    
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 121 122    
Limited partnerships | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 49 65 145 231
Other investments        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 389 618    
Other investments | Level 1        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 0 1    
Other investments | Level 2        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 287 490    
Other investments | Level 3        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 102 127 $ 135 $ 129
Interest Rate Swap        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 114 297    
Participant Loans        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 58 78    
Commodity and Balanced Funds        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets 165 178    
Other Various Investments        
Defined Benefit Plan Disclosure [Line Items]        
Fair value of plan assets $ 52 $ 65