FINANCING ACTIVITIES AND OFF-BALANCE SHEET RISK - Narrative (Details) - USD ($)			1 Months Ended	9 Months Ended
	Jul. 03, 2023	Mar. 24, 2023	Apr. 30, 2022	Sep. 30, 2023	Dec. 31, 2022	Oct. 31, 2019
Debt Instrument [Line Items]
Credit card receivables authorized amount				$ 100,000,000
Credit card receivables outstanding				0
Accrued interest payable and interest expense				$ 197,000,000
Settlement date basis, equities				2 days
Settlement date basis, options				1 day
Robinhood credit | Coastal Bank
Debt Instrument [Line Items]
Customer advance limit	$ 225,000,000
Increment in customer advance limit	50,000,000
Customer advance limit residual amount	$ 25,000,000
Robinhood credit | Coastal Bank | Interest Rate Margin One
Debt Instrument [Line Items]
Variable rate on loan	8.50%
Robinhood credit | Coastal Bank | Interest Rate Margin Two
Debt Instrument [Line Items]
Variable rate on loan	7.00%
Robinhood credit | Coastal Bank | Interest Rate Margin Three
Debt Instrument [Line Items]
Variable rate on loan	5.75%
Robinhood credit | Coastal Bank | Interest Rate Margin Four
Debt Instrument [Line Items]
Variable rate on loan	4.50%
Robinhood credit | Coastal Bank | Interest Rate Margin, Five
Debt Instrument [Line Items]
Variable rate on loan	4.50%
Revolving Credit Facility | Line of Credit | April 2023 Credit Agreement
Debt Instrument [Line Items]
Increase limit on credit facility		$ 1,087,500,000.0000
Agreement fee		$ 3,262,500,000
Unused capacity, commitment fee percentage		0.50%
Revolving Credit Facility | Line of Credit | April 2023 Credit Agreement | SOFR
Debt Instrument [Line Items]
Variable rate on loan		0.10%
Revolving Credit Facility | Line of Credit | April 2023 Credit Facility, Tranche A
Debt Instrument [Line Items]
Variable rate on loan		1.25%
Revolving Credit Facility | Line of Credit | April 2023 Credit Facility, Tranche B and C
Debt Instrument [Line Items]
Variable rate on loan		2.50%
Revolving Credit Facility | Line of Credit | October 2019 Credit Facility
Debt Instrument [Line Items]
Line of credit facility, amount entered into						$ 200,000,000
Outstanding borrowings, long-term				$ 0	$ 0
Revolving Credit Facility | Line of Credit | October 2019 Credit Facility, As Amended
Debt Instrument [Line Items]
Line of credit facility, amount entered into				$ 625,000,000
Revolving Credit Facility | Line of Credit | April 2023 Credit Agreement
Debt Instrument [Line Items]
Line of credit facility, amount entered into		$ 2,175,000,000	$ 2,275,000,000
Line of credit facility, term		364 days	364 days