CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 1,697	$ 1,360	$ 4,816	$ 4,365
Investment securities, available-for-sale:
Net unrealized loss	(2)	(30)	(21)	(2)
Income tax effect	1	11	8	1
Reclassification adjustment for net gain realized in net income	0	0	(21)	0
Income tax effect	0	0	8	0
Defined benefit pension and other postretirement plans:
Net unrealized actuarial loss and prior service credit	0	0	0	(7)
Income tax effect	0	0	0	3
Amortization of actuarial gain and prior service credit realized in net income	(3)	0	(3)	(7)
Income tax effect	1	0	1	3
Derivative instruments classified as cash flow hedges:
Net unrealized (loss) gain	(10)	(14)	118	3
Income tax effect	4	3	(33)	0
Reclassification adjustment for net gain realized in net income	(35)	(16)	(61)	(39)
Income tax effect	9	4	16	8
Foreign currency translation adjustments	0	0	1	0
Other comprehensive (loss) income, net of tax	(35)	(42)	13	(37)
Comprehensive income	$ 1,662	$ 1,318	$ 4,829	$ 4,328