CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 2,575	$ 2,373	$ 8,727	$ 8,729
Investment securities:
Net unrealized gain (loss)	(2)	(3)	(4)	2
Income tax effect	1	1	1	0
Reclassification adjustments	(1)	(1)	(1)	(3)
Income tax effect	0	1	0	1
Defined benefit pension and other postretirement plans:
Net unrealized actuarial gain (loss) and prior service credit (cost)	0	0	(3)	2
Income tax effect	0	0	2	(1)
Reclassification adjustments	7	9	13	15
Income tax effect	(2)	(2)	(3)	(3)
Derivative instruments:
Net unrealized gain (loss)	(95)	(106)	(112)	(247)
Income tax effect	22	23	28	54
Reclassification adjustments	14	(43)	1	(58)
Income tax effect	(2)	9	3	13
Foreign currency translation adjustments	287	277	322	621
Other comprehensive income (loss), net of tax	229	165	247	396
Comprehensive income	$ 2,804	$ 2,538	$ 8,974	$ 9,125