CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash flows from operating activities:
Net income available to common shareholders	$ 1,070	$ 974
Adjustments to reconcile net income to net cash provided by/(used in) operating activities:
Depreciation and amortization	105	97
Deferred income taxes, net	23	(24)
Premium and discount amortization on available-for-sale securities and net (gain)/loss on other investments	40	12
Provisions/(benefits) for credit losses and legal and regulatory proceedings	72	(29)
Share-based compensation expense	149	103
Unrealized (gain)/loss on company-owned life insurance policies, net of expenses	136	(159)
Losses on extinguishment of debt	0	98
Other	25	47
Net change in:
Assets segregated for regulatory purposes excluding cash and cash equivalents	101	(3,000)
Collateralized agreements, net of collateralized financings	10	(178)
Loans provided to financial advisors, net of repayments	(85)	(69)
Brokerage client receivables and other receivables, net	(57)	(425)
Trading instruments, net	126	42
Derivative instruments, net	246	41
Other assets	(97)	(238)
Brokerage client payables and other payables	2,985	4,694
Accrued compensation, commissions and benefits	(261)	160
Purchases and originations of loans held for sale, net of proceeds from sales of securitizations and loans held for sale	(18)	(1)
Net cash provided by operating activities	4,570	2,145
Cash flows from investing activities:
Increase in bank loans, net	(5,377)	(2,620)
Proceeds from sales of loans held for investment	191	248
Purchases of available-for-sale securities	(2,743)	(3,081)
Available-for-sale securities maturations, repayments and redemptions	1,346	1,658
Proceeds from sales of available-for-sale securities	2	969
Cash and cash equivalents acquired in business acquisitions, including those segregated for regulatory purposes, net of cash paid for acquisitions	1,769	(245)
Additions to property and equipment	(68)	(99)
Investment in note receivable	(125)	0
(Purchases)/sales of other investments, net	(33)	21
Other investing activities, net	(81)	(8)
Net cash used in investing activities	(5,119)	(3,157)
Cash flows from financing activities:
Proceeds from senior notes issuances, net of debt issuance costs paid	0	737
Extinguishment of senior notes payable	0	(844)
Increase in bank deposits	4,800	3,539
Repurchases of common stock and share-based awards withheld for payment of withholding tax requirements	(160)	(148)
Dividends on common stock	(200)	(163)
Exercise of stock options and employee stock purchases	44	42
Other financing, net	(5)	(6)
Net cash provided by financing activities	4,598	3,128
Currency adjustment:
Effect of exchange rate changes on cash	(289)	114
Net increase in cash and cash equivalents, including those segregated for regulatory purposes and restricted cash	3,760	2,230
Cash and cash equivalents, including those segregated for regulatory purposes and restricted cash at beginning of year	16,449	9,634
Cash and cash equivalents, including those segregated for regulatory purposes and restricted cash at end of period	20,209	11,864
Cash and cash equivalents, including those segregated for regulatory purposes and restricted cash
Cash and cash equivalents	5,958	5,982
Cash and cash equivalents segregated for regulatory purposes and restricted cash	14,251	5,882
Total cash and cash equivalents, including those segregated for regulatory purposes and restricted cash at end of period	20,209	11,864
Supplemental disclosures of cash flow information:
Cash paid for interest	137	113
Cash paid for income taxes, net	386	335
Cash outflows for lease liabilities	80	84
Non-cash right-of-use assets recorded for new and modified leases	39	101
Restricted stock awards issued as consideration for TriState Capital acquisition	28	0
Effective settlement of note receivable for TriState Capital acquisition	123	0
Common Stock
Supplemental disclosures of cash flow information:
Stock issued as consideration for TriState Capital acquisition	778	0
Preferred Stock
Supplemental disclosures of cash flow information:
Stock issued as consideration for TriState Capital acquisition	120	0
Federal Home Loan Bank Advances [Member]
Cash flows from financing activities:
Proceeds from Federal Home Loan Bank advances	1,025	0
Repayments of Federal Home Loan Bank advances and other borrowed funds	$ (906)	$ (29)