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 [Roll Forward]
Balance at January 1	$ 23	$ 34	$ 70
Additions for tax positions of current year	2	0	0
Additions for tax positions of prior years	29	1	1
Reductions for tax positions of prior years	(14)	(2)	(5)
Settlements	0	(10)	(32)
Balance at December 31	$ 40	$ 23	$ 34