Financial Instruments - Schedule of Assets, Liabilities, and Equity Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Liabilities
Servicing Asset at Fair Value, Amount	$ 35,061	$ 36,261
Fair Value, Measurements, Recurring
Assets
Cash equivalents	123,762	186,410
Loans held for sale	192,622	199,604
Other current assets	11,053	4,007
Total assets	512,601	578,021
Liabilities
Total liabilities	2,340	2,914
Servicing Asset at Fair Value, Amount	35,061	36,261
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Current	140,531	122,259
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Noncurrent	9,572	29,480
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Cash equivalents	123,762	186,410
Loans held for sale	0	0
Other current assets	0	0
Total assets	273,865	338,149
Liabilities
Total liabilities	0	0
Servicing Asset at Fair Value, Amount	0	0
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Current	140,531	122,259
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Noncurrent	9,572
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2)
Assets
Cash equivalents	0	0
Loans held for sale	192,622	199,604
Other current assets	1,840	1,669
Total assets	194,462	201,273
Liabilities
Total liabilities	2,297	1,873
Servicing Asset at Fair Value, Amount	0	0
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Current		0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3)
Assets
Cash equivalents	0	0
Loans held for sale	0	0
Other current assets	9,213	2,338
Total assets	44,274	38,599
Liabilities
Total liabilities	43	1,041
Servicing Asset at Fair Value, Amount	35,061	36,261
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Current		0
Fair Value, Measurements, Recurring \| Money market funds
Assets
Cash equivalents	123,762	186,410
Fair Value, Measurements, Recurring \| Money market funds \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Cash equivalents	123,762	186,410
Fair Value, Measurements, Recurring \| Money market funds \| Significant Other Observable Inputs (Level 2)
Assets
Cash equivalents	0	0
Fair Value, Measurements, Recurring \| Money market funds \| Significant Unobservable Inputs (Level 3)
Assets
Cash equivalents	0	0
U.S. treasury securities \| Fair Value, Measurements, Recurring
Liabilities
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Current	108,326	96,925
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Noncurrent	4,939	29,480
U.S. treasury securities \| Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Liabilities
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Current	108,326	96,925
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Noncurrent	4,939
U.S. treasury securities \| Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2)
Assets
Short-term investments		0
Liabilities
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Current	0
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Noncurrent	0
U.S. treasury securities \| Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3)
Assets
Short-term investments		0
Liabilities
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Current	0
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Noncurrent	0
Agency bonds \| Fair Value, Measurements, Recurring
Liabilities
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Current	32,205	25,334
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Noncurrent	4,633	0
Agency bonds \| Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Liabilities
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Current	32,205	25,334
Debt Securities, Available-for-Sale, Excluding Accrued Interest, Noncurrent	4,633	29,480
Agency bonds \| Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2)
Assets
Short-term investments	0	0
Long-term investments	0	0
Agency bonds \| Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3)
Assets
Short-term investments	0	0
Long-term investments	0	0
Forward sales commitments \| Fair Value, Measurements, Recurring
Assets
Other current assets	1,840	1,669
Liabilities
Accrued liabilities	2,297	1,873
Forward sales commitments \| Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Other current assets	0	0
Liabilities
Accrued liabilities	0	0
Forward sales commitments \| Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2)
Assets
Other current assets	1,840	1,669
Liabilities
Accrued liabilities	2,297	1,873
Forward sales commitments \| Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3)
Assets
Other current assets	0	0
Liabilities
Accrued liabilities	0	0
IRLCs \| Fair Value, Measurements, Recurring
Assets
Other current assets	9,213	2,338
Liabilities
Accrued liabilities	43	1,041
IRLCs \| Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Other current assets	0	0
Liabilities
Accrued liabilities	0	0
IRLCs \| Fair Value, Measurements, Recurring \| Significant Other Observable Inputs (Level 2)
Assets
Other current assets	0	0
Liabilities
Accrued liabilities	0	0
IRLCs \| Fair Value, Measurements, Recurring \| Significant Unobservable Inputs (Level 3)
Assets
Other current assets	9,213	2,338
Liabilities
Accrued liabilities	$ 43	$ 1,041

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

+ Details

Name:	us-gaap_AssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_AssetsFairValueDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

+ References

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtSecuritiesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as noncurrent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(12))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=124260329&loc=d3e26626-111562

+ Details

Name:	us-gaap_AvailableForSaleSecuritiesDebtSecuritiesNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

No definition available.

+ Details

Name:	us-gaap_CashAndCashEquivalentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

+ References

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleExcludingAccruedInterestNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI https://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 22
-URI https://asc.fasb.org/extlink&oid=99393222&loc=SL20226052-175313

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI https://asc.fasb.org/extlink&oid=123594938&loc=d3e13433-108611

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

+ Details

Name:	us-gaap_DerivativeAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI https://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI https://asc.fasb.org/extlink&oid=123594938&loc=d3e13433-108611

Reference 4: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 22
-URI https://asc.fasb.org/extlink&oid=99393222&loc=SL20226052-175313

+ Details

Name:	us-gaap_DerivativeLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value of financial and nonfinancial obligations.

+ References

+ Details

Name:	us-gaap_LiabilitiesFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_LiabilitiesFairValueDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

+ References

No definition available.

+ Details

Name:	us-gaap_LoansHeldForSaleFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 2
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=6469459&loc=d3e122492-111745

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI https://asc.fasb.org/extlink&oid=128311188&loc=d3e122625-111746

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745

+ Details

Name:	us-gaap_ServicingAssetAtFairValueAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CashAndCashEquivalentsAxis=us-gaap_MoneyMarketFundsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=rdfn_AgencyBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_ForwardContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_InterestRateLockCommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: