Income Taxes (Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 78	$ 71	$ 65
Additions, based on tax positions related to current year	8	6	1
Additions for tax positions of prior years	15	6	14
Reductions for tax positions of prior years	(1)	0	(6)
Settlements	(1)	(2)	0
Lapses in statutes of limitation	(13)	(3)	(3)
Ending balance	$ 86	$ 78	$ 71