Income Taxes (Schedule of Deferred Tax Assets and Related Valuation Allowance Recognized for Net Operating and Other Loss Carryforwards and Tax Carryforwards) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Deferred tax assets, tax credit carryforwards	$ 1,796
Valuation allowance, tax credit carryforwards	(963)
Net deferred tax assets, tax credit carryforwards	833
Deferred tax assets, operating loss carryforwards	8
Operating Loss Carryforwards, Valuation Allowance	0
Net deferred tax assets, operating loss carryforwards	8
Deferred tax assets, state and local tax carryforwards	206
State and local tax carryforwards, valuation allowance	(94)
Net deferred tax assets, state and local tax carryforwards	112
Deferred tax assets, other non-attribute	(645)
Other non-attribute, valuation allowance	0
Deferred tax assets, gross, net of deferred tax liabilities	1,357
Deferred tax assets, valuation allowance	(1,057)
Deferred tax assets, net	317	$ 461
Foreign tax credits
Operating Loss Carryforwards [Line Items]
Deferred tax assets, tax credit carryforwards	1,522
Valuation allowance, tax credit carryforwards	(963)
Net deferred tax assets, tax credit carryforwards	559
General business credits
Operating Loss Carryforwards [Line Items]
Deferred tax assets, tax credit carryforwards	274
Valuation allowance, tax credit carryforwards	0
Net deferred tax assets, tax credit carryforwards	274
State and local jurisdiction
Operating Loss Carryforwards [Line Items]
Deferred tax assets, operating loss carryforwards	198
Operating Loss Carryforwards, Valuation Allowance	(94)
Net deferred tax assets, operating loss carryforwards	104
Deferred tax liability
Operating Loss Carryforwards [Line Items]
Deferred tax assets, net	$ 300	$ 453