CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net income	$ 446	$ 312
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	35	32
Deferred income taxes	14	18
Premium and discount amortization on available-for-sale securities and net (gain)/loss on other investments	14	(1)
Provisions/(benefits) for credit losses and legal and regulatory proceedings	(8)	16
Share-based compensation expense	65	43
Unrealized gain on company-owned life insurance policies, net of expenses	(38)	(83)
Other	(1)	22
Net change in:
Assets segregated for regulatory purposes excluding cash and cash equivalents	(7,499)	(2,749)
Collateralized agreements, net of collateralized financings	125	(62)
Loans provided to financial advisors, net of repayments	(56)	5
Brokerage client receivables and other receivables, net	197	254
Trading instruments, net	209	22
Derivative instruments, net	58	(9)
Other assets	(431)	(530)
Brokerage client payables and other payables	5,021	4,970
Accrued compensation, commissions and benefits	(395)	(253)
Purchases and originations of loans held for sale, net of proceeds from sales of securitizations and loans held for sale	(43)	(86)
Net cash provided by/(used in) operating activities	(2,287)	1,921
Cash flows from investing activities:
Increase in bank loans, net	(1,137)	(704)
Proceeds from sales of loans held for investment	75	16
Purchases of available-for-sale securities	(824)	(1,243)
Available-for-sale securities maturations, repayments and redemptions	501	544
Proceeds from sales of available-for-sale securities	0	519
Business acquisitions, net of cash acquired	0	(218)
Additions to property and equipment	(19)	(25)
Investment in note receivable	125	0
Other investing activities, net	(26)	(12)
Net cash used in investing activities	(1,555)	(1,123)
Cash flows from financing activities:
Increase in bank deposits	1,597	989
Repurchases of common stock and share-based awards withheld for payment of withholding tax requirements	(51)	(35)
Dividends on common stock	(60)	(55)
Exercise of stock options and employee stock purchases	17	18
Other financing, net	(5)	0
Net cash provided by financing activities	1,497	891
Currency adjustment:
Effect of exchange rate changes on cash	3	73
Net increase/(decrease) in cash and cash equivalents, including those segregated for regulatory purposes and restricted cash	(2,342)	1,762
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	14,107	11,396
Cash and cash equivalents, including those segregated for regulatory purposes and restricted cash
Cash and cash equivalents	8,216	5,377
Cash and cash equivalents segregated for regulatory purposes and restricted cash	5,891	6,019
Total cash and cash equivalents, including those segregated for regulatory purposes and restricted cash at end of period	14,107	11,396
Supplemental disclosures of cash flow information:
Cash paid for interest	41	35
Cash paid for income taxes, net	12	67
Cash outflows for lease liabilities	25	27
Non-cash right-of-use assets recorded for new and modified leases	16	50
FHLB advances
Cash flows from financing activities:
Repayments of Federal Home Loan Bank advances and other borrowed funds	$ (1)	$ (26)