Retirement Plans (Schedule Of Fair Values Of Defined Benefit Plan Assets Organized By Asset Class And Fair Value Hierarchy Of ASC 820) (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 5,750	$ 5,492
Percentage of defined benefit plan assets	100.00%	100.00%
Fair Value, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 1,302	$ 1,249
Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	1,686	1,548
Fair Value, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	133	515
Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	2,629	2,180
U.S. equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 1,331	$ 1,464
Percentage of defined benefit plan assets	23.00%	27.00%
U.S. equities [Member] | Fair Value, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 785	$ 789
U.S. equities [Member] | Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	10	5
U.S. equities [Member] | Fair Value, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	0	386
U.S. equities [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	536	284
International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 1,164	$ 1,089
Percentage of defined benefit plan assets	20.00%	20.00%
International equities [Member] | Fair Value, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 513	$ 459
International equities [Member] | Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	16	15
International equities [Member] | Fair Value, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	0	0
International equities [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	635	615
Emerging market equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 237	$ 213
Percentage of defined benefit plan assets	4.00%	4.00%
Emerging market equities [Member] | Fair Value, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 0	$ 0
Emerging market equities [Member] | Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	0	0
Emerging market equities [Member] | Fair Value, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	0	0
Emerging market equities [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	237	213
Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 1,648	$ 1,472
Percentage of defined benefit plan assets	29.00%	27.00%
Corporate bonds [Member] | Fair Value, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 0	$ 0
Corporate bonds [Member] | Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	1,202	1,008
Corporate bonds [Member] | Fair Value, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	0	0
Corporate bonds [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	446	464
Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 981	$ 1,052
Percentage of defined benefit plan assets	17.00%	19.00%
Government bonds [Member] | Fair Value, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 0	$ 0
Government bonds [Member] | Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	450	512
Government bonds [Member] | Fair Value, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	0	0
Government bonds [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	531	540
Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 389	$ 202
Percentage of defined benefit plan assets	7.00%	3.00%
Other [Member] | Fair Value, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 4	$ 1
Other [Member] | Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	8	8
Other [Member] | Fair Value, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	133	129
Other [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 244	$ 64