Income Taxes (Schedule of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning unrecognized tax benefits	$ 39	$ 141	$ 124
Current year additions	0	17	0
Effectively settled tax positions	(39)	(102)	0
Ending unrecognized tax benefits	$ 0	$ 39	$ 141