Employee Benefit Plans (Changes In Defined Benefit Obligation And Fair Value Of Defined Benefit Plan Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets, beginning	$ 2,131
Fair value of plan assets, ending	2,448	$ 2,131
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation, beginning	2,992	2,880
Service cost	78	82	$ 92
Interest cost	106	113	112
Actuarial loss (gain)	129	132
Employee contributions	2	1
Curtailments	0	0
Settlements	(6)	(10)
Defined Benefit Plan, Benefit Obligation, Business Combination	3
Divestitures	0	(8)
Benefits paid	(86)	(142)
Plan Amendments	(180)	0
Actual expenses	(2)	(2)
Foreign currency effects	73	(54)
Benefit obligation, ending	3,109	2,992	2,880
Fair value of plan assets, beginning	2,131	1,922
Actual return on plan assets	340	232
Employer contributions	29	183
Employee contributions	2	1
Settlements	(6)	(10)
Divestitures	0	(2)
Benefits Paid	(86)	(142)
Actual Expenses	(2)	(2)
Foreign currency effects	40	(51)
Fair value of plan assets, ending	2,448	2,131	1,922
Funded status	(661)	(861)
Prepaid benefit cost	55	30
Accrued benefit liability - current	(17)	(16)
Accrued benefit liability - long-term	(699)	(875)
Net amount recognized in the balance sheet	(661)	(861)
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation, beginning	171	199
Service cost	2	3	5
Interest cost	6	8	8
Actuarial loss (gain)	(4)	5
Curtailments	0	(38)
Settlements	0
Divestitures	0	0
Benefits paid	(11)	(9)
Plan Amendments	(10)	3
Foreign currency effects	0	0
Benefit obligation, ending	154	171	$ 199
Employer contributions	11	9
Benefits Paid	(11)	(9)
Funded status	(154)	(171)
Accrued benefit liability - current	(12)	(13)
Accrued benefit liability - long-term	(142)	(158)
Net amount recognized in the balance sheet	$ (154)	$ (171)