CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Net income	$ 1,598	$ 1,270	$ 3,005	$ 2,563
Investment securities, available-for-sale:
Net unrealized gain	11	2	28	50
Income tax effect	(4)		(10)	(17)
Reclassification adjustment for net gain realized in net income		(1)		(1)
Defined benefit pension and other postretirement plans:
Net unrealized actuarial loss and prior service credit	(8)	(3)	(7)	(3)
Income tax effect	3	1	3	1
Amortization of actuarial (gain) loss and prior service credit realized in net income	(5)	5	(7)	8
Income tax effect	2	(2)	3	(3)
Derivative instruments classified as cash flow hedges:
Net unrealized (loss) gain	(7)	6	17	15
Income tax effect	1		(3)
Reclassification adjustment for net gain realized in net income	(12)	(6)	(23)	(17)
Income tax effect	2	2	4	5
Other comprehensive (loss) income, net of tax	(17)	4	5	38
Comprehensive income	$ 1,581	$ 1,274	$ 3,010	$ 2,601