Retirement Plans (Schedule Of Net Funded Status) (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Settlements			$ (1,200)
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Funded status, December 31				$ (1,732)	$ (1,896)
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, January 1				13,264	13,683
Service cost				153	160	$ 158
Interest cost				467	536	580
Settlements				(1,653)	(1,295)
Actuarial (gain) loss				(1,089)	913
Defined Benefit Plan, Benefit Obligation, Business Combination				0	0
Defined Benefit Plan, Benefit Obligation, Divestiture				0	33
Plan amendments				2	3
Benefits Paid				(677)	(769)
Effect of foreign currency exchange rate movements				0	0
Benefit obligation, December 31	$ 13,683			10,467	13,264	13,683
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, January 1				11,368	10,312
Actual return on plan assets				(332)	1,830
Company contributions				29	1,290
Benefits paid				(677)	(769)
Settlements	(9)	$ (8)		$ (1,653)	$ (1,295)
Defined benefit plan, plan assets, acquired plan assets				0	0
Effect of foreign currency exchange rate movements				$ 0	$ 0
Fair value of plan assets, December 31	10,312			8,735	11,368	10,312
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Funded status, December 31				(54)	(71)
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit obligation, January 1				247	219
Service cost				5	4	4
Interest cost				8	9	9
Settlements				(2)	(4)
Actuarial (gain) loss				(17)	2
Defined Benefit Plan, Benefit Obligation, Business Combination				0	5
Defined Benefit Plan, Benefit Obligation, Divestiture				0	0
Plan amendments				0	0
Benefits Paid				(9)	(8)
Effect of foreign currency exchange rate movements				(17)	20
Benefit obligation, December 31	219			215	247	219
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets, January 1				176	153
Actual return on plan assets				(2)	10
Company contributions				10	10
Benefits paid				(9)	(8)
Settlements				$ (2)	$ (4)
Defined benefit plan, plan assets, acquired plan assets				0	3
Effect of foreign currency exchange rate movements				$ (12)	$ 12
Fair value of plan assets, December 31	$ 153			$ 161	$ 176	$ 153