FINANCING ACTIVITIES AND OFF-BALANCE SHEET RISK (Details)		1 Months Ended				12 Months Ended
	Mar. 24, 2023 USD ($)	Nov. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Apr. 30, 2022 USD ($)	Oct. 31, 2019 USD ($)	Dec. 31, 2023 USD ($) day	Apr. 30, 2021 USD ($)	Oct. 31, 2020 USD ($)
Debt Instrument [Line Items]
Credit card receivables authorized amount						$ 100,000,000
Credit card receivables outstanding						0
Customer advance balance						$ 205,000,000
Settlement date basis, equities | day						2
Settlement date basis, options | day						1
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
Secured Overnight Financing Rate, Interest Period Of One Month
Debt Instrument [Line Items]
Variable rate on loan			0.11%
Secured Overnight Financing Rate, Interest Period Of Three Months
Debt Instrument [Line Items]
Variable rate on loan			0.26%
Secured Overnight Financing Rate, Interest Period Of Six Months
Debt Instrument [Line Items]
Variable rate on loan			0.43%
Base Rate
Debt Instrument [Line Items]
Variable rate on loan			0.00%
Revolving Credit Facility | October 2019 Credit Facility | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, amount entered into					$ 200,000,000
Outstanding borrowings, long-term			$ 0			$ 0
Commitment fee percentage			0.10%
Revolving Credit Facility | October 2019 Credit Facility | Eurodollar | Line of Credit
Debt Instrument [Line Items]
Variable rate on loan					1.00%
Revolving Credit Facility | October 2019 Credit Facility | Federal Reserve Bank of New York Rate | Line of Credit
Debt Instrument [Line Items]
Variable rate on loan			0.50%		0.50%
Revolving Credit Facility | October 2019 Credit Facility | Eurodollar, One Month Interest Period | Line of Credit
Debt Instrument [Line Items]
Variable rate on loan					1.00%
Revolving Credit Facility | October 2019 Credit Facility | Secured Overnight Financing Rate (SOFR) | Line of Credit
Debt Instrument [Line Items]
Variable rate on loan			1.00%
Revolving Credit Facility | October 2019 Credit Facility | Secured Overnight Financing Rate, Interest Period Of One Month | Line of Credit
Debt Instrument [Line Items]
Variable rate on loan			1.00%
Revolving Credit Facility | October 2019 Credit Facility, As Amended | Line of Credit
Debt Instrument [Line Items]
Line of credit facility, amount entered into							$ 625,000,000	$ 600,000,000
Revolving Credit Facility | April 2023 Credit Agreement | Line of Credit
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
Revolving Credit Facility | Line of Credit | April 2023 Credit Agreement
Debt Instrument [Line Items]
Line of credit facility, increase limit	$ 1,087,500,000.0000
Line of credit facility, remaining borrowing capacity	$ 3,262,500,000
Unused capacity, commitment fee percentage	0.50%
Revolving Credit Facility | Line of Credit | April 2023 Credit Agreement | Secured Overnight Financing Rate (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 2022 Credit Facility, Tranche B and C
Debt Instrument [Line Items]
Variable rate on loan	2.50%