Income Taxes (Income Tax Expense (Benefit)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax [Line Items]
Valuation Allowance, Deferred Tax Asset, Change in Amount	$ 127
U.S.	836	$ 47	$ (358)
International	32	27	27
Total	$ 868	$ 74	$ (331)