CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 3,959	$ 3,126
Investment securities:
Net unrealized gain (loss)	(10)	(1)
Income tax effect	2	0
Defined benefit pension and other postretirement plans:
Net unrealized actuarial gain (loss) and prior service credit (cost)	1	(1)
Income tax effect	0	1
Reclassification adjustments	1	3
Income tax effect	0	(1)
Derivative instruments:
Net unrealized gain (loss)	114	(297)
Income tax effect	(22)	63
Reclassification adjustments	(6)	(18)
Income tax effect	0	5
Foreign currency translation adjustments	(588)	1,046
Other comprehensive income (loss), net of tax	(508)	800
Comprehensive income	$ 3,451	$ 3,926