Pension and Other Benefit Programs - Fair Value Of Plan Assets (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	$ 946	$ 819
Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	144	135
Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	796	677
Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	6	7
Cash
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	7	8
Cash | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	7	8
Cash | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	0	0
Cash | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	0	0
U.S. large-cap
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	25	21
U.S. large-cap | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	0	0
U.S. large-cap | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	25	21
U.S. large-cap | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	0	0
U.S. small-cap
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	7	5
U.S. small-cap | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	0	0
U.S. small-cap | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	7	5
U.S. small-cap | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	0	0
International
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	13	11
International | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	0	0
International | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	13	11
International | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	0	0
Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	894	774
Fixed income securities | Quoted Prices in Active Markets for Identical Assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	137	127
Fixed income securities | Significant Observable Inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	751	640
Fixed income securities | Significant Unobservable Inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Fair Value Measurements	$ 6	$ 7