Retirement Plans (Schedule Of Changes In Defined Benefit Plan Obligations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension Benefits [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	$ 1,249	$ 1,308
Service cost	15	15	$ 33
Interest cost	42	42	52
Actuarial loss (gain)	59	63
Plan amendments		2
Plan curtailments		(31)
Plan settlements		(94)
Foreign exchange rate changes	2	1
Benefits paid	(88)	(57)
Benefit obligation at end of year	1,279	1,249	1,308
Change in plan assets:
Fair value of plan assets at beginning of year	985	1,059
Actual return on plan assets	122	61
Employer contributions	14	16
Plan settlements		(94)
Benefits paid	(88)	(57)
Foreign exchange rate changes	2
Fair value of plan assets at end of year	1,035	985	1,059
Funded status at end of year	(244)	(264)
Amounts recognized in balance sheet:
Other long-term assets	4	3
Other current liabilities	(13)	(13)
Other long-term liabilities	(235)	(254)
Net amount	(244)	(264)
Amounts recognized in accumulated other comprehensive earnings:
Net actuarial loss (gain)	257	285
Prior service cost (credit)	6	8
Total	263	293
Postretirement Benefits [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	21	23
Service cost			1
Interest cost		1	1
Actuarial loss (gain)		(1)
Participant contributions	1
Benefits paid	(3)	(2)
Benefit obligation at end of year	19	21	$ 23
Change in plan assets:
Employer contributions	2	2
Participant contributions	1
Benefits paid	(3)	(2)
Funded status at end of year	(19)	(21)
Amounts recognized in balance sheet:
Other current liabilities	(3)	(3)
Other long-term liabilities	(16)	(18)
Net amount	(19)	(21)
Amounts recognized in accumulated other comprehensive earnings:
Net actuarial loss (gain)	(11)	(11)
Prior service cost (credit)	(3)	(5)
Total	$ (14)	$ (16)