Pension, Other Postretirement Benefits and Savings Plans - Fair Values of Pension Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	$ 4,970	$ 4,780
Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	185	370
Pension Plan | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	4,970	4,780	$ 4,445
Pension Plan | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	3,041	2,740	2,464
Pension Plan | Fair Value, Inputs, Level 1, 2 and 3 | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	4,292	4,031
Pension Plan | Fair Value, Inputs, Level 1, 2 and 3 | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	2,327	2,159
Pension Plan | Quoted Prices in Active Markets for Identical Assets (Level 1) | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	122	47
Pension Plan | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	194	178
Pension Plan | Significant Unobservable Inputs (Level 3) | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	3	4
Pension Plan | Significant Unobservable Inputs (Level 3) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	29	23
Pension Plan | Significant Other Observable Inputs (Level 2) | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	4,167	3,980
Pension Plan | Significant Other Observable Inputs (Level 2) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	2,104	1,958
Pension Plan | Cash and short term securities | Fair Value, Inputs, Level 1, 2 and 3 | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	122	47
Pension Plan | Cash and short term securities | Fair Value, Inputs, Level 1, 2 and 3 | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	46	33
Pension Plan | Cash and short term securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	122	47
Pension Plan | Cash and short term securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	42	29
Pension Plan | Cash and short term securities | Significant Other Observable Inputs (Level 2) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	4	4
Pension Plan | Equity Securities, Common and Preferred Stock | Fair Value, Inputs, Level 1, 2 and 3 | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	24	24
Pension Plan | Equity Securities, Common and Preferred Stock | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	24	24
Pension Plan | Equity Securities, Commingled Funds | Fair Value, Inputs, Level 1, 2 and 3 | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	19	36
Pension Plan | Equity Securities, Commingled Funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	19	36
Pension Plan | Equity Securities, Commingled Funds | Fair Value Measured at Net Asset Value Per Share | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	23	9
Pension Plan | Equity Securities, Commingled Funds | Fair Value Measured at Net Asset Value Per Share | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	62	69
Pension Plan | Equity Securities, Mutual Funds | Fair Value, Inputs, Level 1, 2 and 3 | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	6	5
Pension Plan | Equity Securities, Mutual Funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	6	5
Pension Plan | Equity Securities, Mutual Funds | Fair Value Measured at Net Asset Value Per Share | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	4	11
Pension Plan | Debt Securities, Corporate Bonds | Fair Value, Inputs, Level 1, 2 and 3 | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	2,843	2,577
Pension Plan | Debt Securities, Corporate Bonds | Fair Value, Inputs, Level 1, 2 and 3 | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	230	190
Pension Plan | Debt Securities, Corporate Bonds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	24	10
Pension Plan | Debt Securities, Corporate Bonds | Significant Unobservable Inputs (Level 3) | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	1	1
Pension Plan | Debt Securities, Corporate Bonds | Significant Other Observable Inputs (Level 2) | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	2,842	2,576
Pension Plan | Debt Securities, Corporate Bonds | Significant Other Observable Inputs (Level 2) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	206	180
Pension Plan | Debt Securities, Government Bonds | Fair Value, Inputs, Level 1, 2 and 3 | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	1,038	1,120
Pension Plan | Debt Securities, Government Bonds | Fair Value, Inputs, Level 1, 2 and 3 | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	2,503	2,271
Pension Plan | Debt Securities, Government Bonds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	42	60
Pension Plan | Debt Securities, Government Bonds | Significant Other Observable Inputs (Level 2) | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	1,038	1,120
Pension Plan | Debt Securities, Government Bonds | Significant Other Observable Inputs (Level 2) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	2,461	2,211
Pension Plan | Debt Securities, Repurchase Agreements | Fair Value, Inputs, Level 1, 2 and 3 | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	(650)	(511)
Pension Plan | Debt Securities, Repurchase Agreements | Significant Other Observable Inputs (Level 2) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	(650)	(511)
Pension Plan | Debt Securities, Asset-backed Securities | Fair Value, Inputs, Level 1, 2 and 3 | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	280	283
Pension Plan | Debt Securities, Asset-backed Securities | Fair Value, Inputs, Level 1, 2 and 3 | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	76	74
Pension Plan | Debt Securities, Asset-backed Securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	8	5
Pension Plan | Debt Securities, Asset-backed Securities | Significant Unobservable Inputs (Level 3) | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value		1
Pension Plan | Debt Securities, Asset-backed Securities | Significant Other Observable Inputs (Level 2) | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	280	282
Pension Plan | Debt Securities, Asset-backed Securities | Significant Other Observable Inputs (Level 2) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	68	69
Pension Plan | Debt Securities, Commingled Funds | Fair Value, Inputs, Level 1, 2 and 3 | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	20
Pension Plan | Debt Securities, Commingled Funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	20
Pension Plan | Debt Securities, Commingled Funds | Fair Value Measured at Net Asset Value Per Share | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	295	310
Pension Plan | Debt Securities, Commingled Funds | Fair Value Measured at Net Asset Value Per Share | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	665	604
Pension Plan | Debt Securities, Mutual Funds | Fair Value, Inputs, Level 1, 2 and 3 | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	19	19
Pension Plan | Debt Securities, Mutual Funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	9	9
Pension Plan | Debt Securities, Mutual Funds | Significant Other Observable Inputs (Level 2) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	10	10
Pension Plan | Debt Securities, Mutual Funds | Fair Value Measured at Net Asset Value Per Share | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	148	141
Pension Plan | Debt Securities, Mutual Funds | Fair Value Measured at Net Asset Value Per Share | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	81	7
Pension Plan | Alternatives, Insurance Contracts | Fair Value, Inputs, Level 1, 2 and 3 | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	2	2
Pension Plan | Alternatives, Insurance Contracts | Fair Value, Inputs, Level 1, 2 and 3 | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	28	22
Pension Plan | Alternatives, Insurance Contracts | Significant Unobservable Inputs (Level 3) | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	2	2
Pension Plan | Alternatives, Insurance Contracts | Significant Unobservable Inputs (Level 3) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	28	22	$ 19
Pension Plan | Alternatives, Other Investments | Fair Value, Inputs, Level 1, 2 and 3 | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	7	2
Pension Plan | Alternatives, Other Investments | Fair Value, Inputs, Level 1, 2 and 3 | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	6	(4)
Pension Plan | Alternatives, Other Investments | Significant Unobservable Inputs (Level 3) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	1	1
Pension Plan | Alternatives, Other Investments | Significant Other Observable Inputs (Level 2) | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	7	2
Pension Plan | Alternatives, Other Investments | Significant Other Observable Inputs (Level 2) | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	5	(5)
Pension Plan | Equity Securities, Partnership Interests | Fair Value Measured at Net Asset Value Per Share | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	166	267
Pension Plan | Debt Securities, Partnership Interests | Fair Value Measured at Net Asset Value Per Share | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	102
Pension Plan | Short Term Securities, Commingled Funds | Fair Value Measured at Net Asset Value Per Share | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	22	67
Pension Plan | Short Term Securities, Commingled Funds | Fair Value Measured at Net Asset Value Per Share | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	3	4
Pension Plan | Alternatives, Commingled Funds | Fair Value Measured at Net Asset Value Per Share | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	6	6
Pension Plan | Investments Before Other Plan Assets | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	5,048	4,825
Pension Plan | Investments Before Other Plan Assets | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	3,148	2,860
Pension Plan | Other Assets | United States
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	(78)	(45)
Pension Plan | Other Assets | Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	$ (107)	$ (120)