Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Cash flows from operating activities:
Net income	$ 2,438	$ 2,073
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Deferred income taxes	7	9
Depreciation and amortization	51	49
Amortization of right-of-use assets	22	20
Employee stock plan compensation	80	75
Unrealized (gains) losses on other investments, net	(18)	(21)
Customer bad debt expense	14	2
Shares distributed to customers under IBKR Promotions	17	7
Change in operating assets and liabilities:
Securities - segregated for regulatory purposes	4,283	446
Securities borrowed	(1,678)	(729)
Securities purchased under agreements to resell	(2,672)	549
Financial instruments owned, at fair value	(1,461)	(870)
Receivables from customers	(11,548)	(4,844)
Other receivables	(615)	1,644
Other assets	(135)	(59)
Securities loaned	5,471	1,542
Financial instruments sold but not yet purchased, at fair value	188	52
Payable to customers	11,567	1,678
Other payables	875	552
Net cash provided by operating activities	6,886	2,175
Cash flows from investing activities:
Purchases of other investments	(28)	(10)
Distributions received and proceeds from sales of other investments		23
Purchase of property, equipment and intangible assets	(34)	(40)
Net cash used in investing activities	(62)	(27)
Cash flows from financing activities:
Short-term borrowings, net	16	(7)
Dividends paid to stockholders	(65)	(31)
Distributions to noncontrolling interests	(576)	(453)
Repurchases of common stock for employee tax withholdings	(54)	(34)
Proceeds from sales of treasury stock	57	34
Payments made under the Tax Receivable Agreement	(25)	(25)
Net cash used in financing activities	(647)	(516)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	41	(26)
Net increase in cash, cash equivalents and restricted cash	6,218	1,606
Cash, cash equivalents and restricted cash at beginning of period	32,593	28,603
Cash, cash equivalents and restricted cash at end of period	38,811	30,209
Cash, cash equivalents and restricted cash
Cash and cash equivalents	3,595	3,824
Cash segregated for regulatory purposes	35,216	26,385
Cash, cash equivalents and restricted cash	38,811	30,209
Supplemental disclosures of cash flow information:
Cash paid for interest	3,119	2,375
Cash paid for taxes, net	213	162
Cash paid for amounts included in lease liabilities	31	26
Non-cash financing activities:
Issuance of common stock in exchange of member interests in IBG LLC	39	229
Redemption of member interests from IBG Holdings LLC	(39)	(229)
Adjustments to additional paid-in capital for changes in proportionate ownership in IBG LLC	40	32
Adjustments to noncontrolling interests for changes in proportionate ownership in IBG LLC	$ (40)	$ (32)