Pension, Other Postretirement Benefits and Savings Plans - Fair Values of Pension Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
United States
Defined Benefit Plan Disclosure [Line Items]
Plan assets, fair value	$ 3,425	$ 3,847
Total plan assets, fair value	4,445	4,978
United States | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	48	39
United States | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	3,375	3,805
United States | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	2	3
United States | Cash and short term securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	48	55
United States | Cash and short term securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	48	39
United States | Cash and short term securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	16
United States | Cash and short term securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Equity Securities, Common and Preferred Stock
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Equity Securities, Common and Preferred Stock | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Equity Securities, Common and Preferred Stock | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Equity Securities, Common and Preferred Stock | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Equity Securities, Commingled Funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value	11	54
Total plan assets, fair value	0	0
United States | Equity Securities, Commingled Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Equity Securities, Commingled Funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Equity Securities, Commingled Funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Equity Securities, Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value	0	0
Total plan assets, fair value	0	0
United States | Equity Securities, Mutual Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Equity Securities, Mutual Funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Equity Securities, Mutual Funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Debt Securities, Corporate Bonds
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	2,344	2,699
United States | Debt Securities, Corporate Bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Debt Securities, Corporate Bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	2,344	2,698
United States | Debt Securities, Corporate Bonds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	1
United States | Debt Securities, Government Bonds
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	968	1,033
United States | Debt Securities, Government Bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Debt Securities, Government Bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	968	1,033
United States | Debt Securities, Government Bonds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Debt Securities, Repurchase Agreements
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Debt Securities, Repurchase Agreements | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Debt Securities, Repurchase Agreements | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Debt Securities, Repurchase Agreements | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Debt Securities, Asset-backed Securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	63	58
United States | Debt Securities, Asset-backed Securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Debt Securities, Asset-backed Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	63	58
United States | Debt Securities, Asset-backed Securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Debt Securities, Commingled Funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value	603	682
Total plan assets, fair value		0
United States | Debt Securities, Commingled Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value		0
United States | Debt Securities, Commingled Funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value		0
United States | Debt Securities, Commingled Funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value		0
United States | Debt Securities, Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value	90	111
Total plan assets, fair value	0	0
United States | Debt Securities, Mutual Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Debt Securities, Mutual Funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Debt Securities, Mutual Funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Alternatives, Real Estate
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value		0
United States | Alternatives, Real Estate | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value		0
United States | Alternatives, Real Estate | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value		0
United States | Alternatives, Real Estate | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value		0
United States | Alternatives, Insurance Contracts
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	2	2
United States | Alternatives, Insurance Contracts | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Alternatives, Insurance Contracts | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Alternatives, Insurance Contracts | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	2	2
United States | Alternatives, Other Investments
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Alternatives, Other Investments | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Alternatives, Other Investments | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Alternatives, Other Investments | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
United States | Equity Securities, Partnership Interests
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value	247	238
United States | Short Term Securities, Commingled Funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value	59	67
United States | Alternatives, Commingled Funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value	0	0
United States | Investments Before Other Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	4,435	4,999
United States | Other Assets
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	10	(21)
Non-U.S.
Defined Benefit Plan Disclosure [Line Items]
Plan assets, fair value	1,864	2,044
Total plan assets, fair value	2,464	2,806
Non-U.S. | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	155	163
Non-U.S. | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	1,688	1,725
Non-U.S. | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	21	156
Non-U.S. | Cash and short term securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	29	20
Non-U.S. | Cash and short term securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	26	19
Non-U.S. | Cash and short term securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	3	1
Non-U.S. | Cash and short term securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
Non-U.S. | Equity Securities, Common and Preferred Stock
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	19	24
Non-U.S. | Equity Securities, Common and Preferred Stock | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	19	24
Non-U.S. | Equity Securities, Common and Preferred Stock | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
Non-U.S. | Equity Securities, Common and Preferred Stock | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
Non-U.S. | Equity Securities, Commingled Funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value	56	66
Total plan assets, fair value	14	148
Non-U.S. | Equity Securities, Commingled Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	14	17
Non-U.S. | Equity Securities, Commingled Funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
Non-U.S. | Equity Securities, Commingled Funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	131
Non-U.S. | Equity Securities, Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value	7	18
Total plan assets, fair value	4	5
Non-U.S. | Equity Securities, Mutual Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	4	5
Non-U.S. | Equity Securities, Mutual Funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
Non-U.S. | Equity Securities, Mutual Funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
Non-U.S. | Debt Securities, Corporate Bonds
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	171	156
Non-U.S. | Debt Securities, Corporate Bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	17	14
Non-U.S. | Debt Securities, Corporate Bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	154	142
Non-U.S. | Debt Securities, Corporate Bonds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
Non-U.S. | Debt Securities, Government Bonds
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	2,158	2,358
Non-U.S. | Debt Securities, Government Bonds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	62	73
Non-U.S. | Debt Securities, Government Bonds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	2,096	2,285
Non-U.S. | Debt Securities, Government Bonds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
Non-U.S. | Debt Securities, Repurchase Agreements
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	(641)	(763)
Non-U.S. | Debt Securities, Repurchase Agreements | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
Non-U.S. | Debt Securities, Repurchase Agreements | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	(641)	(763)
Non-U.S. | Debt Securities, Repurchase Agreements | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
Non-U.S. | Debt Securities, Asset-backed Securities
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	67	47
Non-U.S. | Debt Securities, Asset-backed Securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	5	4
Non-U.S. | Debt Securities, Asset-backed Securities | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	62	43
Non-U.S. | Debt Securities, Asset-backed Securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
Non-U.S. | Debt Securities, Commingled Funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value	638	579
Total plan assets, fair value		10
Non-U.S. | Debt Securities, Commingled Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value		0
Non-U.S. | Debt Securities, Commingled Funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value		10
Non-U.S. | Debt Securities, Commingled Funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value		0
Non-U.S. | Debt Securities, Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value	7	7
Total plan assets, fair value	18	7
Non-U.S. | Debt Securities, Mutual Funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	8	7
Non-U.S. | Debt Securities, Mutual Funds | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	10	0
Non-U.S. | Debt Securities, Mutual Funds | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
Non-U.S. | Alternatives, Real Estate
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value		4
Non-U.S. | Alternatives, Real Estate | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value		0
Non-U.S. | Alternatives, Real Estate | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value		0
Non-U.S. | Alternatives, Real Estate | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value		4
Non-U.S. | Alternatives, Insurance Contracts
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	19	18
Non-U.S. | Alternatives, Insurance Contracts | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
Non-U.S. | Alternatives, Insurance Contracts | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
Non-U.S. | Alternatives, Insurance Contracts | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	19	18
Non-U.S. | Alternatives, Other Investments
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	6	10
Non-U.S. | Alternatives, Other Investments | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	0	0
Non-U.S. | Alternatives, Other Investments | Significant Other Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	4	7
Non-U.S. | Alternatives, Other Investments | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	2	3
Non-U.S. | Equity Securities, Partnership Interests
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value	0	0
Non-U.S. | Short Term Securities, Commingled Funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value	7	6
Non-U.S. | Alternatives, Commingled Funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value	5	95
Non-U.S. | Investments Before Other Plan Assets
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	2,584	2,815
Non-U.S. | Other Assets
Defined Benefit Plan Disclosure [Line Items]
Total plan assets, fair value	$ (120)	$ (9)