Income Taxes Components of Provision for Income Taxes on Continuing Operations (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2014	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Components of Income Tax [Line Items]
Income from Continuing Operations before Income Taxes, Domestic				$ 1,155	$ 1,051	$ 1,370
Current
Federal				1,975	(477)	109
State				101	(21)	15
Foreign				1,403	906	585
Total				3,479	408	709
Deferred
Federal				(523)	201	(175)
State				(51)	(31)	(6)
Foreign				(667)	22	(121)
Total				(1,241)	192	(302)
Income tax provision				2,238	600	407
Income (Loss) from Continuing Operations before Income Taxes, Foreign				431	1,100	546
Income Taxes Paid				1,388	1,163	782
Taxes Payable, Current				1,538	337
Undistributed Earnings of Foreign Subsidiaries				5,500
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount		$ 780
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount	$ (85)		$ (51)	$ (31)	(24)	(24)
Global Workplace Solutions
Deferred
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount					$ 680	$ 35