Income Taxes (Net Deferred Tax Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Abstract]
Deferred tax assets	$ 951	$ 813
Deferred tax liabilities	(347)	(451)
Net deferred tax assets	$ 604	$ 362

Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards classified as noncurrent.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant