Accounts Receivable (Schedule Of Allowance For Doubtful Accounts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance for Doubtful Accounts, Beginning of Period	$ 72
Allowance for Doubtful Accounts, End of Period	57	$ 72
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance for Doubtful Accounts, Beginning of Period	72	71	$ 93
Charged to Other Revenue	67	61	69
Charged (Credited) to Switched and Nonswitched Revenue and Other Accounts	(17)		(3)
Write-offs, net of Recoveries	(65)	(60)	(88)
Allowance for Doubtful Accounts, End of Period	$ 57	$ 72	$ 71