Income Taxes (Valuation Allowance on Deferred Tax Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Valuation Allowance, Deferred Tax Asset [Roll Forward]
Balance, beginning of year	$ 136	$ 117	$ 214
Charged to costs and expenses	22	32	18
Other adjustments	(15)	(13)	(115)
Balance, ending of year	143	136	117
Federal
Valuation Allowance, Deferred Tax Asset [Roll Forward]
Balance, beginning of year	3	0	0
Charged to costs and expenses	12	3	0
Other adjustments	0	0	0
Balance, ending of year	15	3	0
State
Valuation Allowance, Deferred Tax Asset [Roll Forward]
Balance, beginning of year	127	106	196
Charged to costs and expenses	5	34	24
Other adjustments	(16)	(13)	(114)
Balance, ending of year	116	127	106
Foreign Operations
Valuation Allowance, Deferred Tax Asset [Roll Forward]
Balance, beginning of year	6	11	18
Charged to costs and expenses	5	(5)	(6)
Other adjustments	1	0	(1)
Balance, ending of year	$ 12	$ 6	$ 11