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, 2016	Sep. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 5,019	$ 4,863
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	$ 1,855	$ 1,600
Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	2,759	2,892
Fair Value, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	405	371
U.S. equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 1,678	$ 1,673
Percentage of defined benefit plan assets	33.00%	34.00%
U.S. equities [Member] | Fair Value, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 1,081	$ 956
U.S. equities [Member] | Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	305	460
U.S. equities [Member] | Fair Value, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	292	257
International equities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 1,234	$ 1,179
Percentage of defined benefit plan assets	25.00%	24.00%
International equities [Member] | Fair Value, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 627	$ 502
International equities [Member] | Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	607	677
International 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]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 257	$ 211
Percentage of defined benefit plan assets	5.00%	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	257	211
Emerging market equities [Member] | Fair Value, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	0	0
Corporate bonds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 648	$ 628
Percentage of defined benefit plan assets	13.00%	13.00%
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	648	628
Corporate 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]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 752	$ 676
Percentage of defined benefit plan assets	15.00%	14.00%
Government bonds [Member] | Fair Value, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 3	$ 2
Government bonds [Member] | Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	749	674
Government 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]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 122	$ 175
Percentage of defined benefit plan assets	2.00%	4.00%
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	122	175
High yield bonds [Member] | Fair Value, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	0	0
Other [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 328	$ 321
Percentage of defined benefit plan assets	7.00%	7.00%
Other [Member] | Fair Value, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 144	$ 140
Other [Member] | Fair Value, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	71	67
Other [Member] | Fair Value, Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of defined benefit plan assets	$ 113	$ 114