Debt Instrument, Covenant, Minimum Net Worth

No definition available.

Name:	rdn_DebtInstrumentCovenantMinimumNetWorth
Namespace Prefix:	rdn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Debt instrument, covenant, net worth.

+ References

No definition available.

+ Details

Name:	rdn_DebtInstrumentCovenantNetWorth
Namespace Prefix:	rdn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Investments, Number Of States

+ References

No definition available.

+ Details

Name:	rdn_InvestmentsNumberOfStates
Namespace Prefix:	rdn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Net consolidated assets (liabilities).

+ References

No definition available.

+ Details

Name:	rdn_NetConsolidatedAssetsLiabilities
Namespace Prefix:	rdn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number Of Investments

+ References

No definition available.

+ Details

Name:	rdn_NumberOfInvestments
Namespace Prefix:	rdn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of debt instrument, covenant, net worth.

+ References

No definition available.

+ Details

Name:	rdn_PercentageOfDebtInstrumentCovenantNetWorth
Namespace Prefix:	rdn_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of loans on properties.

+ References

No definition available.

+ Details

Name:	rdn_PercentageOfLoansOnProperties
Namespace Prefix:	rdn_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Private Offering Of Mortgage Loans.

+ References

No definition available.

+ Details

Name:	rdn_PrivateOfferingOfMortgageLoans
Namespace Prefix:	rdn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Residential mortgage loans held for sale-unpaid principal balance.

+ References

No definition available.

+ Details

Name:	rdn_ResidentialMortgageLoansHeldForSale-UnpaidPrincipalBalance
Namespace Prefix:	rdn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Unpaid principal balance of loan.

+ References

No definition available.

+ Details

Name:	rdn_UnpaidPrincipalBalanceOfLoan
Namespace Prefix:	rdn_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- 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

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

- Definition

Reflects the carrying amount of loans and leases for which agreements to acquire or dispose exist.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 942
-SubTopic 825
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478898/942-825-50-2

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 942
-SubTopic 825
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478898/942-825-50-1

+ Details

Name:	us-gaap_LoansAndLeasesReceivableCommitmentsToPurchaseOrSell
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 80
-Name Accounting Standards Codification
-Section 55
-Paragraph 14
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480078/944-80-55-14

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 944
-SubTopic 80
-Name Accounting Standards Codification
-Section 55
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480078/944-80-55-9

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1)(c))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1)(6))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478777/944-210-S99-1

+ Details

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

- Details

Name:	srt_ConsolidatedEntitiesAxis=us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	srt_StatementGeographicalAxis=stpr_CA
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=rdn_OtherStatesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=rdn_RadianMortgageCapitalMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=rdn_RadianMortgageCapitalTrust2025-J1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=rdn_RadianMortgageCapitalTrust2025-J2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Residential Mortgage Loans - Additional Information (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2025 USD ($) State Investment	Jun. 30, 2025 USD ($) State Investment	Dec. 31, 2024 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Mortgage loans held for sale-at fair value	$ 698,367	$ 698,367	$ 519,885
Variable Interest Entity, Primary Beneficiary
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net consolidated assets (liabilities)	30,000	30,000
Residential Mortgage Loans Held for Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Mortgage loans held for sale-at fair value	$ 698,000	$ 698,000	$ 520,000
Number of investments \| Investment	832	832
Residential mortgage loans held for sale-unpaid principal balance	$ 690,000	$ 690,000
Number of states \| State	46	46
Unpaid principal balance of loan	76.00%	99.00%
Commitments to purchase and fund mortgage loans		$ 230,000
Residential Mortgage Loans Held for Sale \| California
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of loans on properties	24.00%	24.00%
Residential Mortgage Loans Held for Sale \| Other State
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of loans on properties	10.00%	10.00%
Residential Mortgage Loans Held for Sale \| Financial Asset, Equal to or Greater than 90 Days Past Due
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of investments \| Investment	0	0
Minimum \| Residential Mortgage Loans Held for Sale \| Other State
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of loans on properties	0.00%	0.00%
Radian Mortgage Capital \| Residential Mortgage Loans Held for Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage of net worth for debt covenants	6.00%	6.00%
Net worth for debt covenants	$ 74,000	$ 74,000
Minimum net worth for debt covenants	$ 45,000	45,000
Radian Mortgage Capital Trust 2025-J1
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Private offering of mortgage loans		368,000
Radian Mortgage Capital Trust 2025-J2
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Private offering of mortgage loans		$ 396,000