FINANCING ACTIVITIES AND OFF-BALANCE SHEET RISK (Details) - USD ($)		1 Months Ended			3 Months Ended		9 Months Ended		12 Months Ended
	Mar. 21, 2025	May 31, 2024	Mar. 31, 2024	Nov. 30, 2023	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024	Jun. 12, 2025
Debt Instrument [Line Items]
Credit card receivables							$ 2,917,000,000	$ 239,000,000
Net interest revenues					$ 456,000,000	$ 274,000,000	1,103,000,000	813,000,000
Customer advance balance					207,000,000		207,000,000
Settlement date basis, equities		2 days
Settlement date basis, options		1 day
Cryptocurrencies, fair value					51,800,000,000		51,800,000,000		$ 35,200,000,000
Accrued for legal and regulatory contingencies					61,000,000		61,000,000		128,000,000
Remote
Debt Instrument [Line Items]
Accrued for legal and regulatory contingencies					0		0		$ 0
Coastal Bank | Robinhood credit
Debt Instrument [Line Items]
Customer advance limit				$ 300,000,000
Coastal Bank | Robinhood credit | Interest Rate Margin One
Debt Instrument [Line Items]
Variable rate on loan				3.75%
Customer advance limit threshold				$ 150,000,000
Coastal Bank | Robinhood credit | Interest Rate Margin Two
Debt Instrument [Line Items]
Variable rate on loan				3.00%
Customer advance limit threshold				$ 150,000,000
Robinhood Credit
Debt Instrument [Line Items]
Net interest revenues					14,000,000	$ 0	26,000,000	$ 0
RHM March 2025 Credit Facility | Secured Overnight Financing Rate, Interest Period Of One Month
Debt Instrument [Line Items]
Variable rate on loan	0.10%
RHM March 2025 Credit Facility | Base Rate
Debt Instrument [Line Items]
Variable rate on loan	0.00%
Barclays Arrangement Maturing November 2026 | Robinhood Credit
Debt Instrument [Line Items]
Line of credit facility, amount entered into					200,000,000		$ 200,000,000
Barclays Arrangement Maturing November 2026 | Robinhood Credit | Minimum
Debt Instrument [Line Items]
Undrawn fees rate							0.25%
Barclays Arrangement Maturing November 2026 | Robinhood Credit | Maximum
Debt Instrument [Line Items]
Undrawn fees rate							0.35%
Barclays Arrangement Maturing November 2026 | Commercial Paper Rate | Robinhood Credit
Debt Instrument [Line Items]
Variable rate on loan							1.75%
SVB Arrangement Maturing April 2027 | Robinhood Credit
Debt Instrument [Line Items]
Line of credit facility, amount entered into					$ 150,000,000		$ 150,000,000
Undrawn fees rate							0.25%
Borrowings bear interest rate					1.50%		1.50%
Wells Fargo Bank Arrangement Maturing August 2028 | Robinhood Credit
Debt Instrument [Line Items]
Line of credit facility, amount entered into					$ 300,000,000		$ 300,000,000
Wells Fargo Bank Arrangement Maturing August 2028 | Robinhood Credit | Minimum
Debt Instrument [Line Items]
Undrawn fees rate							0.275%
Wells Fargo Bank Arrangement Maturing August 2028 | Robinhood Credit | Maximum
Debt Instrument [Line Items]
Undrawn fees rate							0.325%
Wells Fargo Bank Arrangement Maturing August 2028 | Daily Simple SOFR | Robinhood Credit
Debt Instrument [Line Items]
Variable rate on loan							1.40%
Wells Fargo Bank Arrangement Maturing August 2028 | Daily Simple SOFR During - Controlled Or Early Amortization Period | Robinhood Credit
Debt Instrument [Line Items]
Variable rate on loan							2.00%
SVB And Barclays Arrangements | Robinhood Credit
Debt Instrument [Line Items]
Weighted average interest									7.81%
SVB, Barclays and WF Arrangements | Robinhood Credit
Debt Instrument [Line Items]
Outstanding borrowings, long-term					$ 378,000,000		$ 378,000,000		$ 131,000,000
Weighted average interest					6.45%		6.45%
Credit card receivables					$ 1,400,000,000		$ 2,900,000,000		748,000,000
Provision for credit losses					501,000,000		501,000,000		179,000,000
Revolving Credit Facility | March 2024 credit facility
Debt Instrument [Line Items]
Line of credit facility, amount entered into	$ 2,250,000,000
Line of credit facility, term			364 days
Revolving Credit Facility | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, increase limit	1,000,000,000									$ 1,125,000,000
Outstanding borrowings, long-term									$ 0
Revolving Credit Facility | RHM March 2025 Credit Facility | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, amount entered into	1,000,000,000
Line of credit facility, increase limit	250,000,000
Line of credit facility, remaining borrowing capacity	$ 1,250,000,000
Variable rate on loan	1.50%
Commitment fee percentage	0.25%
Revolving Credit Facility | RHM March 2025 Credit Facility | Line of Credit | Federal Reserve Bank of New York Rate
Debt Instrument [Line Items]
Variable rate on loan	0.50%
Revolving Credit Facility | RHM March 2025 Credit Facility | Line of Credit | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Variable rate on loan	1.00%
Revolving Credit Facility | RHS March 2025 Credit Agreement | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, amount entered into	$ 2,650,000,000
Line of credit facility, increase limit	1,325,000,000
Line of credit facility, remaining borrowing capacity	$ 3,975,000,000
Commitment fee percentage	0.50%
Line of credit facility, term	364 days
Outstanding borrowings, long-term					$ 0		$ 0
Revolving Credit Facility | RHS March 2025 Credit Agreement | Line of Credit | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Variable rate on loan	0.10%
Revolving Credit Facility | RHS March 2025 Credit Agreement, Tranche A | Line of Credit
Debt Instrument [Line Items]
Variable rate on loan	1.25%
Revolving Credit Facility | RHM March 2025 Credit Facility, Tranche B and C | Line of Credit
Debt Instrument [Line Items]
Variable rate on loan	2.50%