Accounts Receivable (Schedule Of Allowance For Doubtful Accounts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance for Doubtful Accounts, Beginning of the Period	$ 105
Allowance for Doubtful Accounts, End of the Period	120	$ 105
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance for Doubtful Accounts, Beginning of the Period	105	69	$ 131
Charged to Other Revenue	109	93	87
Write-offs, net of Recoveries	(83)	(89)	(149)
Reclassified to Northwest Operations	(11)
Allowance for Doubtful Accounts, End of the Period	120	105	$ 69
Restatement Adjustment [Member] | Impact Of Adoption Of ACS 606 [Member] | Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance for Doubtful Accounts, Beginning of the Period	$ 32
Allowance for Doubtful Accounts, End of the Period		$ 32