v3.19.3.a.u2
Post-Employment Benefits - Assets (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value $ 10,637 $ 8,904
Unfunded commitments to investments in the private funds 571 518
U.S. large cap    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 2,873 2,168
U.S. mid and small cap    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 648 515
International    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 2,202 1,671
U.S. government securities    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 562 476
Corporate debt instruments    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 1,266 1,150
Non U.S. government securities    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 445 405
Other    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 320 199
Absolute return funds    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 1,557 1,684
Commodities    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 32 59
Cash and Cash Equivalents    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 182 192
Other    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 550 385
Quoted Prices in Active Markets    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 3,661 2,837
Quoted Prices in Active Markets | U.S. large cap    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 1,647 1,319
Quoted Prices in Active Markets | U.S. mid and small cap    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 548 226
Quoted Prices in Active Markets | International    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 464 370
Quoted Prices in Active Markets | U.S. government securities    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 52 51
Quoted Prices in Active Markets | Corporate debt instruments    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 362 269
Quoted Prices in Active Markets | Non U.S. government securities    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 3 5
Quoted Prices in Active Markets | Other    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 69 15
Quoted Prices in Active Markets | Absolute return funds    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 424 448
Quoted Prices in Active Markets | Cash and Cash Equivalents    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 84 123
Quoted Prices in Active Markets | Other    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 8 11
Significant Other Observable Inputs    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 1,114 1,030
Significant Other Observable Inputs | U.S. large cap    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value   5
Significant Other Observable Inputs | U.S. mid and small cap    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 4  
Significant Other Observable Inputs | U.S. government securities    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 357 269
Significant Other Observable Inputs | Corporate debt instruments    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 724 701
Significant Other Observable Inputs | Non U.S. government securities    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 2  
Significant Other Observable Inputs | Other    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 27 55
Significant Unobservable Inputs    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 3 4
Significant Unobservable Inputs | U.S. mid and small cap    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 2  
Significant Unobservable Inputs | Commodities    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 1 4
Measured at NAV    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 5,859 5,033
Measured at NAV | U.S. large cap    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 1,226 844
Measured at NAV | U.S. mid and small cap    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 94 289
Measured at NAV | International    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 1,738 1,301
Measured at NAV | U.S. government securities    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 153 156
Measured at NAV | Corporate debt instruments    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 180 180
Measured at NAV | Non U.S. government securities    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 440 400
Measured at NAV | Other    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 224 129
Measured at NAV | Absolute return funds    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 1,133 1,236
Measured at NAV | Commodities    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 31 55
Measured at NAV | Cash and Cash Equivalents    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value 98 69
Measured at NAV | Other    
Defined benefit plans disclosures    
Defined benefit plans' assets at fair value $ 542 $ 374
Equities | Minimum    
Defined benefit plans disclosures    
Redemption notice period 7 days  
Equities | Maximum    
Defined benefit plans disclosures    
Redemption notice period 30 days  
Fixed Income Securities    
Defined benefit plans disclosures    
Maximum amount of fund with redemption limit to 33% $ 235  
Maximum amount of fund with redemption limit to 25% $ 100  
Maximum redemption fund percentage - 33% 33.00%  
Maximum redemption fund percentage - 25% 25.00%  
Investments that are subject to lock until 2022 $ 45  
Fixed Income Securities | Minimum    
Defined benefit plans disclosures    
Redemption notice period 2 days  
Fixed Income Securities | Maximum    
Defined benefit plans disclosures    
Redemption notice period 14 days  
Absolute return funds | Minimum    
Defined benefit plans disclosures    
Redemption notice period 5 days  
Absolute return funds | Maximum    
Defined benefit plans disclosures    
Redemption notice period 90 days