Income Taxes (Schedule of Unrecognized Tax Benefits Roll Forward) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	$ 42	$ 38	$ 34
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	1	1	1
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	1	1	1
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	51
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits	48	44	15
Unrecognized Tax Benefits, Additions based on tax positions related to the current year	0	0	0
Unrecognized Tax Benefits, Additions for tax positions of prior years	5	11	29
Unrecognized Tax Benefits, Reductions for tax positions of prior years	0	(5)	0
Unrecognized Tax Benefits, Settlements	0	(2)	0
Unrecognized Tax Benefits, Expiration of statute of limitations	0	0	0
Unrecognized Tax Benefits	$ 53	$ 48	$ 44