Debt - Warehouse Lines of Credit (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Warehouse agreement borrowings	$ 39,029	$ 21,302
Warehouse Agreement Borrowings
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	105,000	64,000
Warehouse agreement borrowings	39,029	21,302
Western Alliance Bank \| Warehouse Agreement Borrowings
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	50,000	24,500
Warehouse agreement borrowings	$ 18,277	$ 8,489
Debt, weighted average interest rate	3.25%	3.79%
Stated Cash Interest Rate	3.25%
Western Alliance Bank \| Warehouse Agreement Borrowings \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	2.00%
Texas Capital Bank, N.A. \| Warehouse Agreement Borrowings
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 40,000	$ 24,500
Warehouse agreement borrowings	$ 12,903	$ 10,210
Debt, weighted average interest rate	3.35%	3.51%
Stated Cash Interest Rate	3.35%
Debt instrument, decrease in rate of interest accruing on outstanding principal	0.25%
Flagstar Bank, FSB \| Warehouse Agreement Borrowings
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 15,000	$ 15,000
Warehouse agreement borrowings	$ 7,849	$ 2,603
Debt, weighted average interest rate	3.00%	3.69%
Stated Cash Interest Rate	3.00%
Flagstar Bank, FSB \| Warehouse Agreement Borrowings \| London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Debt instrument, basis spread on variable rate	2.00%

Debt Instrument, Decrease In Rate Of Interest Accruing On Outstanding Principal

No definition available.

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Namespace Prefix:	rdfn_
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- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Weighted average interest rate of debt outstanding.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of the outstanding short-term borrowings under a revolving line of credit used by mortgage bankers to finance the origination or purchase of loans.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(13))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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Balance Type:	credit
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- Details

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- Details

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