Stock-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
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
Percent level objectives were met through the current year for performance shares awarded primarily in 2016	97.00%
Shares to be distributed early next fiscal year from the 2016 performance shares	1,818,508
Total compensation expense for stock option and incentive shares plans	$ 216	$ 110	$ 145
Income tax benefits recognized in income statement for compensation arrangements	42	$ 33	$ 45
Unrecognized compensation cost related to non-vested awards granted	$ 182
Unrecognized compensation cost is expected to be recognized, weighted-average period, years	1 year 1 month
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	2,375,313
Performance shares awarded in 2016, outstanding and contingent on meeting performance objectives through 2018	1,874,750
Performance shares awarded in 2018, outstanding and contingent on meeting performance objectives through 2019	2,261,700
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	11,600,000
Weighted-average price of shares granted	$ 12.13	$ 8.36	$ 9.02
Cash received for stock options exercises	$ 143	$ 148	$ 31
Options exercised, total intrinsic value	53	36	9
Employee Service Share-based Compensation, Tax Benefit from Exercise of Stock Options	$ 7	$ 2	$ 2
Risk-free interest rate	2.40%	1.70%	1.90%
Expected dividend yield	2.90%	3.60%	3.80%
Expected volatility rate	23.00%	24.00%	27.00%
Expected life of option	7 years	7 years	7 years
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares issued	167,837
Shares withheld for income tax	142,163
Shares vested in period	310,000
Unvested shares outstanding	1,276,200
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	10,300,000
Shares vested in period	310,000
Unvested shares outstanding	6,898,000	4,999,000
Total fair value of shares vested	$ 20	$ 245	$ 11
Cash paid primarily for tax withholdings	$ 9	101	4
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	159,965
Restricted stock awarded	12,228
Restricted stock units awarded	2,038
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	$ 216	115	159
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