Post-Employment Benefits - Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	$ 13,838	$ 12,371
Unfunded commitments to investments in the private funds	585	523
U.S. large cap
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	3,664	3,410
U.S. mid and small cap
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	936	775
International
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	2,902	2,654
U.S. government securities
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	366	475
Corporate debt instruments
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	1,709	1,408
Non U.S. government securities
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	626	523
Other,
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	510	503
Absolute return funds
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	1,934	1,618
Cash and Cash Equivalents
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	266	281
Other.
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	925	724
Quoted Prices in Active Markets
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	4,958	4,578
Quoted Prices in Active Markets | U.S. large cap
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	2,403	2,202
Quoted Prices in Active Markets | U.S. mid and small cap
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	876	721
Quoted Prices in Active Markets | International
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	591	542
Quoted Prices in Active Markets | U.S. government securities
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	21	23
Quoted Prices in Active Markets | Corporate debt instruments
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	434	425
Quoted Prices in Active Markets | Non U.S. government securities
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	33	16
Quoted Prices in Active Markets | Other,
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	87	159
Quoted Prices in Active Markets | Absolute return funds
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	476	462
Quoted Prices in Active Markets | Cash and Cash Equivalents
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	35	19
Quoted Prices in Active Markets | Other.
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	2	9
Significant Other Observable Inputs
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	1,697	1,269
Significant Other Observable Inputs | U.S. government securities
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	325	289
Significant Other Observable Inputs | Corporate debt instruments
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	1,260	908
Significant Other Observable Inputs | Non U.S. government securities
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	1
Significant Other Observable Inputs | Other,
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	111	72
Significant Unobservable Inputs
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	4	3
Significant Unobservable Inputs | U.S. mid and small cap
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	4	3
Measured at NAV
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	7,179	6,521
Measured at NAV | U.S. large cap
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	1,261	1,208
Measured at NAV | U.S. mid and small cap
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	56	51
Measured at NAV | International
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	2,311	2,112
Measured at NAV | U.S. government securities
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	20	163
Measured at NAV | Corporate debt instruments
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	15	75
Measured at NAV | Non U.S. government securities
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	592	507
Measured at NAV | Other,
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	312	272
Measured at NAV | Absolute return funds
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	1,458	1,156
Measured at NAV | Cash and Cash Equivalents
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	231	262
Measured at NAV | Other.
Defined benefit plans disclosures
Defined benefit plans' assets at fair value	$ 923	$ 715
Equities | Minimum
Defined benefit plans disclosures
Redemption notice period	2 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%	$ 290
Maximum amount of fund with redemption limit to 25%	$ 150
Maximum redemption fund percentage - 33%	33.00%
Maximum redemption fund percentage - 25%	25.00%
Investments that are subject to lock until 2022	$ 50
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 fund | Minimum
Defined benefit plans disclosures
Redemption notice period	5 days
Absolute return fund | Maximum
Defined benefit plans disclosures
Redemption notice period	90 days