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, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 5,492	$ 5,476
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	$ 1,249	$ 1,670
Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	1,548	1,078
Fair Value, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	515	471
Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	2,180	2,257
U.S. equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 1,464	$ 1,643
Percentage of defined benefit plan assets	27.00%	30.00%
U.S. equities [Member] | Fair Value, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 789	$ 968
U.S. equities [Member] | Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	5	5
U.S. equities [Member] | Fair Value, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	386	350
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	284	320
International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 1,089	$ 1,361
Percentage of defined benefit plan assets	20.00%	25.00%
International equities [Member] | Fair Value, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 459	$ 595
International equities [Member] | Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	15	21
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	615	745
Emerging market equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 213	$ 243
Percentage of defined benefit plan assets	4.00%	5.00%
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	213	243
Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 1,472	$ 1,119
Percentage of defined benefit plan assets	27.00%	20.00%
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	1,008	696
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	464	423
Government bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 1,052	$ 788
Percentage of defined benefit plan assets	19.00%	14.00%
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	512	350
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	540	438
High yield bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 0	$ 10
Percentage of defined benefit plan assets	0.00%	0.00%
High yield bonds [Member] | Fair Value, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 0	$ 0
High yield bonds [Member] | Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	0	0
High yield bonds [Member] | Fair Value, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	0	0
High yield 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	0	10
Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 202	$ 312
Percentage of defined benefit plan assets	3.00%	6.00%
Other [Member] | Fair Value, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 1	$ 107
Other [Member] | Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	8	6
Other [Member] | Fair Value, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	129	121
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	$ 64	$ 78