Income Taxes (Reconciliation of Valuation Allowance of Deferred Tax Assets) (Details) - Valuation Allowance of Deferred Tax Assets - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 234	$ 350	$ 311
Change in assessment (a)	(2)	1	(28)
Current year operations	2	(271)	48
Foreign currency and other	(43)	154	19
Balance at end of year	$ 191	$ 234	$ 350