Stockholders' Equity (Summary Of Dividends Paid On Common Stock) (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended												12 Months Ended
	Oct. 01, 2020	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stockholders Equity [Line Items]
Common stock dividends paid, Amount		$ 41	$ 43	$ 42	$ 34	$ 34	$ 35	$ 37	$ 34	$ 37	$ 38	$ 42	$ 32	$ 257	$ 140	$ 149
Common stock dividends, rate per share	$ 0.26	$ 0.11	$ 0.11	$ 0.11	$ 0.09	$ 0.09	$ 0.09	$ 0.09	$ 0.08	$ 0.08	$ 0.08	$ 0.08	$ 0.06
Special Dividend [Member]
Stockholders Equity [Line Items]
Common stock dividends paid, Amount		$ 97
Common stock dividends, rate per share		$ 0.26