Leases - Maturity of Lease Liabilities (Details) $ in Thousands	3 Months Ended
Mar. 31, 2022 USD ($)
Operating leases
2022, excluding the three months ended March 31, 2022	$ 12,903
2023	16,244
2024	14,653
2025	11,233
2026	10,495
Thereafter	6,434
Total lease payments	71,962
Less: Interest	6,908
Present value of lease liabilities	65,054
Finance leases
2022, excluding the three months ended March 31, 2022	482
2023	629
2024	544
2025	220
2026	2
Thereafter	0
Total lease payments	1,877
Less: Interest	142
Present value of lease liabilities	1,735
Other Leases
2022, excluding the three months ended March 31, 2022	644
2023	397
2024	346
2025	272
2026	28
Thereafter	0
Total lease payments	1,687
Total Lease Obligations
2022, excluding the three months ended March 31, 2022	14,029
2023	17,270
2024	15,543
2025	11,725
2026	10,525
Thereafter	6,434
Total lease payments	75,526
Operating lease, capitalized interest expense	2,515
Financing lease, capitalized interest expense	$ 77

Finance Lease, Liability, to be Paid, after Year Four

No definition available.

Name:	rdfn_FinanceLeaseLiabilityToBePaidAfterYearFour
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Financing Lease, Capitalized Interest Expense

+ References

No definition available.

+ Details

Name:	rdfn_FinancingLeaseCapitalizedInterestExpense
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Lessee, Lease Liability, Payments, Due

+ References

No definition available.

+ Details

Name:	rdfn_LesseeLeaseLiabilityPaymentsDue
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lessee, Lease Liability, Payments Due

+ References

No definition available.

+ Details

Name:	rdfn_LesseeLeaseLiabilityPaymentsDueAbstract
Namespace Prefix:	rdfn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Lessee, Lease Liability, Payments, Due After Year Four

+ References

No definition available.

+ Details

Name:	rdfn_LesseeLeaseLiabilityPaymentsDueAfterYearFour
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lessee, Lease Liability, Payments, Due Next Twelve Months

+ References

No definition available.

+ Details

Name:	rdfn_LesseeLeaseLiabilityPaymentsDueNextTwelveMonths
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lessee, Lease Liability, Payments, Due Year Four

+ References

No definition available.

+ Details

Name:	rdfn_LesseeLeaseLiabilityPaymentsDueYearFour
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lessee, Lease Liability, Payments, Due Year One

+ References

No definition available.

+ Details

Name:	rdfn_LesseeLeaseLiabilityPaymentsDueYearOne
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lessee, Lease Liability, Payments, Due Year Three

+ References

No definition available.

+ Details

Name:	rdfn_LesseeLeaseLiabilityPaymentsDueYearThree
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lessee, Lease Liability, Payments, Due Year Two

+ References

No definition available.

+ Details

Name:	rdfn_LesseeLeaseLiabilityPaymentsDueYearTwo
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lessee, Operating Lease, Liability, Other, Payments, After Year Four

+ References

No definition available.

+ Details

Name:	rdfn_LesseeOperatingLeaseLiabilityOtherPaymentsAfterYearFour
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lessee, Operating Lease, Liability, Other, Payments, Due

+ References

No definition available.

+ Details

Name:	rdfn_LesseeOperatingLeaseLiabilityOtherPaymentsDue
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lessee, Operating Lease, Liability, Other, Payments, Due

+ References

No definition available.

+ Details

Name:	rdfn_LesseeOperatingLeaseLiabilityOtherPaymentsDueAbstract
Namespace Prefix:	rdfn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Lessee, Operating Lease, Liability, Other, Payments, Due Next Twelve Months

+ References

No definition available.

+ Details

Name:	rdfn_LesseeOperatingLeaseLiabilityOtherPaymentsDueNextTwelveMonths
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lessee, Operating Lease, Liability, Other, Payments, Due Year Four

+ References

No definition available.

+ Details

Name:	rdfn_LesseeOperatingLeaseLiabilityOtherPaymentsDueYearFour
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lessee, Operating Lease, Liability, Other, Payments, Due Year One

+ References

No definition available.

+ Details

Name:	rdfn_LesseeOperatingLeaseLiabilityOtherPaymentsDueYearOne
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lessee, Operating Lease, Liability, Other, Payments, Due Year Three

+ References

No definition available.

+ Details

Name:	rdfn_LesseeOperatingLeaseLiabilityOtherPaymentsDueYearThree
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lessee, Operating Lease, Liability, Other, Payments, Due Year Two

+ References

No definition available.

+ Details

Name:	rdfn_LesseeOperatingLeaseLiabilityOtherPaymentsDueYearTwo
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lessee, Operating Lease, Liability, to be Paid, After Year Four

+ References

No definition available.

+ Details

Name:	rdfn_LesseeOperatingLeaseLiabilityToBePaidAfterYearFour
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Operating Lease, Capitalized Interest Expense

+ References

No definition available.

+ Details

Name:	rdfn_OperatingLeaseCapitalizedInterestExpense
Namespace Prefix:	rdfn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

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

- Definition

Present value of lessee's discounted obligation for lease payments from finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918701-209980

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977

+ Details

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

- Definition

Amount of lessee's undiscounted obligation for lease payments for finance lease.

+ References

+ Details

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

- Definition

Amount of lessee's undiscounted obligation for lease payment for finance lease to be paid in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

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

- Definition

Amount of lessee's undiscounted obligation for lease payment for finance lease to be paid in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

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

- Definition

Amount of lessee's undiscounted obligation for lease payment for finance lease to be paid in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

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

- Definition

Amount of lessee's undiscounted obligation for lease payment for finance lease to be paid in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

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

- Definition

Amount of lessee's undiscounted obligation for lease payment for finance lease to be paid in remainder of current fiscal year.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918701-209980

+ Details

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

- Definition

Amount of lessee's undiscounted obligation for lease payments in excess of discounted obligation for lease payments for finance lease.

+ References

+ Details

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

- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease.

+ References

+ Details

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

- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

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

- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

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

- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

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

- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

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

- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease having initial or remaining lease term in excess of one year to be paid in remainder of current fiscal year.

+ References

+ Details

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

- Definition

Amount of lessee's undiscounted obligation for lease payments in excess of discounted obligation for lease payments for operating lease.

+ References

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Present value of lessee's discounted obligation for lease payments from operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977

+ Details

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