Stock-Based Compensation (Narrative)(Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance shares awarded in 2013, outstanding and contingent on meeting performance objectives through 2016 and provision of service by the employees		4,944,575
Percent level objectives were met through the current year for performance shares awarded primarily in 2013		86.00%
Performance shares at the current fiscal year's performance level		4,252,335
Performance shares distributed from the 2013 performance shares	2,549,083
Performance shares distributed from 2013 performance share awards, shares issued	1,393,715
Performance shares distributed from 2013 performance share awards, withheld for income taxes	944,002
Performance shares distributed from 2013 performance share awards, paid in cash	211,366
Performance shares distributed from 2013 performance share awards, employees providing one additional year of service	1,691,986
Performance shares distributed from 2013 performance share awards, employees with one additional year of service, issued as shares	1,070,264
Performance shares distributed from 2013 performance share awards, employees with one additional year of service, withheld for income taxes	616,734
Performance shares distributed from 2013 performance share awards, employees with one additional year of service, paid in cash	4,988
Performance shares canceled from 2013 Performance Share Awards	11,266
Total compensation expense for stock option and incentive shares plans	$ 110	$ 145	$ 24
Income tax benefits recognized in income statement for compensation arrangements	33	$ 45	$ 2
Unrecognized compensation cost related to non-vested awards granted	$ 149
Unrecognized compensation cost is expected to be recognized, weighted-average period, years	1 year 6 months
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance shares awarded in 2017, outstanding and contingent on meeting performance objectives through 2019	2,388,125
Performance shares awarded in 2016, outstanding and contingent on meeting performance objectives through 2018		2,178,388
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of options granted at the closing market price of common stock on the grant date	100.00%
Amount of stock option vesting per year	one-third
Stock option expiration years from date of grant years	10 years
Share-based compensation arrangement by share-based payment award, number of shares available for grant	11,500,000
Weighted-average price of shares granted	$ 8.36	$ 9.02	$ 12.48
Cash received for stock options exercises	$ 148	$ 31	$ 36
Options exercised, total intrinsic value	36	9	16
Actual tax benefit realized from tax deductions related to option exercises	$ 2	$ 2	$ 10
Risk-free interest rate	1.70%	1.90%	1.90%
Expected dividend yield	3.60%	3.80%	3.10%
Expected volatility rate	24.00%	27.00%	28.00%
Expected life of option	7 years	7 years	7 years
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vested in period	130,641
Common shares issued	84,398
Shares withheld for income tax	46,243
Unvested shares outstanding	1,194,500
Incentive Shares Member
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares available for grant	12,900,000
Shares vested in period	4,372,000
Unvested shares outstanding	4,999,000	7,328,000
Total fair value of shares vested	$ 245	$ 11	$ 9
Cash paid primarily for tax withholdings	$ 101	4	5
Restricted Stock For Non Management Directors Member
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares available for grant	174,335
Restricted stock awarded	17,984
Restricted stock units awarded	2,248
Includes both Continuing and Discontinued Operations [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation expense for stock option and incentive shares plans	$ 115	159	30
Discontinued Operations, Held-for-sale or Disposed of by Sale [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total compensation expense for stock option and incentive shares plans	$ 5	$ 14	$ 6