Retirement Plans (Net Periodic Pension Expense For Qualified And Nonqualified U.S. Defined Benefit Plans) (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	$ (376)
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost				$ 160	$ 158	$ 161
Interest cost				536	580	597
Expected return on plan assets				(774)	(815)	(783)
Amortization of Gains (Losses)				339	400	428
Amortization of prior service cost				28	41	43
Recognized Net Gain (Loss) Due to Curtailments				23	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	$ 3	$ 3	$ 439	383	445	15
Defined Benefit Plan, Other Cost (Credit)				22	0	0
Net periodic pension expense				717	809	461
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost				4	4	6
Interest cost				9	9	10
Expected return on plan assets				(11)	(10)	(11)
Amortization of Gains (Losses)				2	1	1
Amortization of prior service cost				0	0	0
Recognized Net Gain (Loss) Due to Curtailments				0	0	0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement				1	0	0
Defined Benefit Plan, Other Cost (Credit)				0	0	0
Net periodic pension expense				$ 5	$ 4	$ 6