Retirement Plans and Other Retiree Benefits - Allocation of Plan Assets and Level of Valuation Input, by Major Asset Category (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Percent of fixed income assets invested in US treasury or agency securities	50.00%	50.00%
Other Retiree Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 37	$ 54	$ 0
Other Retiree Benefit Plans | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	24	36
Other Retiree Benefit Plans | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	13	18
Other Retiree Benefit Plans | Cash and cash equivalents | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	1
Other Retiree Benefit Plans | U.S. common stocks | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	3
Other Retiree Benefit Plans | International common stocks | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Retiree Benefit Plans | Pooled funds | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	4
Other Retiree Benefit Plans | Fixed income securities | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	20	28
Other Retiree Benefit Plans | Guaranteed investment contracts | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Other Retiree Benefit Plans | Domestic, developed and emerging markets equity funds | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	7	8
Other Retiree Benefit Plans | Fixed income funds | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	4
Other Retiree Benefit Plans | Hedge funds | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	2
Other Retiree Benefit Plans | Multi-Asset funds | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	3
Other Retiree Benefit Plans | Real estate funds | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	1
Other Retiree Benefit Plans | Other assets and liabilities, net
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,806	1,568	1,812
United States | Pension Plans | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,187	1,076
United States | Pension Plans | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	704	534
United States | Pension Plans | Cash and cash equivalents | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	41	29
United States | Pension Plans | U.S. common stocks | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	49	75
United States | Pension Plans | International common stocks | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
United States | Pension Plans | Pooled funds | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	29	106
United States | Pension Plans | Fixed income securities | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1,067	865
United States | Pension Plans | Guaranteed investment contracts | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	1	1
United States | Pension Plans | Domestic, developed and emerging markets equity funds | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	328	229
United States | Pension Plans | Fixed income funds | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	177	116
United States | Pension Plans | Hedge funds | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	56
United States | Pension Plans | Multi-Asset funds | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	155	94
United States | Pension Plans | Real estate funds | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	41	39
United States | Pension Plans | Other assets and liabilities, net
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	(85)	(42)
International | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	586	510	$ 575
International | Pension Plans | Fair Value, Inputs, Level 1, 2 and 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	181	173
International | Pension Plans | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	405	337
International | Pension Plans | Cash and cash equivalents | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	15	9
International | Pension Plans | U.S. common stocks | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	3
International | Pension Plans | International common stocks | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	3	4
International | Pension Plans | Pooled funds | Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	104	82
International | Pension Plans | Fixed income securities | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	14	24
International | Pension Plans | Guaranteed investment contracts | Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	42	51
International | Pension Plans | Domestic, developed and emerging markets equity funds | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	165	134
International | Pension Plans | Fixed income funds | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	196	173
International | Pension Plans | Hedge funds | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	17	6
International | Pension Plans | Multi-Asset funds | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	2	2
International | Pension Plans | Real estate funds | Fair Value Measured at Net Asset Value Per Share
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	25	22
International | Pension Plans | Other assets and liabilities, net
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0