Income Tax (Tax Credit Carryforwards) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	$ 105	$ 58
Foreign Tax Authority
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	88
Foreign Tax Authority | 2020-2024
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	18
Foreign Tax Authority | 2025-2029
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	70
Foreign Tax Authority | 2030-2034
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	0
Foreign Tax Authority | 2035-2039
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	0
Foreign Tax Authority | Indefinite
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	0
General business tax credit carryforward
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	17
General business tax credit carryforward | 2020-2024
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	0
General business tax credit carryforward | 2025-2029
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	0
General business tax credit carryforward | 2030-2034
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	0
General business tax credit carryforward | 2035-2039
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	17
General business tax credit carryforward | Indefinite
Tax Credit Carryforward [Line Items]
Tax credit carryforwards	$ 0