Name:	rdn_CededCommissionPercentageChargedOnCededRiskInForceInEventOfUnexercisedCommutationOption
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Percentage of commissions due to ceded insurance.

No definition available.

Name:	rdn_CededInsuranceCommissionPercentage
Namespace Prefix:	rdn_
Data Type:	num:percentItemType
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Period Type:	duration

First Lien Primary Mortgage Insurance Risk In Force Ceded

No definition available.

Name:	rdn_FirstLienPrimaryMortgageInsuranceRiskInForceCeded
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The percentage of the entity's ceded risk related to a quota share arrangement which was subjected to a change in ceding commission percentage.

No definition available.

Name:	rdn_PercentageofCededInsuranceSubjectedtoChangeinCommissionPercentage
Namespace Prefix:	rdn_
Data Type:	num:percentItemType
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Period Type:	duration

Percentage of New Insurance Written To Be Ceded

No definition available.

Name:	rdn_PercentageOfNewInsuranceWrittenToBeCeded
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Data Type:	num:percentItemType
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This concept represents the percentage of premium and losses incurred allowed to be ceded under reinsurance agreements.

No definition available.

Name:	rdn_PercentageOfPremiumAndLossesIncurredToBeCeded
Namespace Prefix:	rdn_
Data Type:	num:percentItemType
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Period Type:	instant

Percentage of reinsurance able to be commuted, as per the quota share reinsurance agreement

No definition available.

Name:	rdn_PercentageOfReinsuranceAbleToBeCommuted
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Data Type:	num:percentItemType
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Period Type:	instant

The amortization period related to prepaid reinsurance commissions.

No definition available.

Name:	rdn_PrepaidReinsuranceCommissionsAmortizationPeriod
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A commission paid on the ceded insurance risk in lieu of recapturing the risk per the initial agreement.

No definition available.

Name:	rdn_ProfitCommissionEarnedonCededRisk
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Balance Type:	credit
Period Type:	duration

Name:	rdn_ReinsuranceTransactionDetailsLineItems
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Represents upfront payments to the entity related to commissions on ceded insurance risk not yet earned. The amortization of this amount will be netted against the entity's deferred policy acquisition costs on the ceded policies.

No definition available.

Name:	rdn_UnearnedCedingCommissions
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Data Type:	xbrli:monetaryItemType
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Amount of earned premiums ceded to other entities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 17

-Article 12

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 235

-Section S99

-Paragraph 2

-Subparagraph (SX 210.12-17)

-URI http://asc.fasb.org/extlink&oid=34713774&loc=d3e574992-122915

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.1)

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 605

-Section 50

-Paragraph 1

-Subparagraph (b),(c)(2)

-URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 1

-Article 7

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 605

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6486662&loc=d3e27175-158546

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of written premiums ceded to other entities.

Name:	us-gaap_CededPremiumsWritten
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Amount of fees and commissions from financial services and banking activities and correspondent clearing. Includes fees from depositor accounts, credit cards, merchant discounts, and fiduciary and trust activities, guarantee fees, investment advisory, management, and administrative fees, transfer agent fees, and insurance commissions.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.13)

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 13

-Article 9

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

The unexpired portion of premiums ceded on policies in force as of the balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Prepaid Reinsurance Premiums

-URI http://asc.fasb.org/extlink&oid=6521719

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 340

-Section 25

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6485982&loc=d3e22818-158507

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

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

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
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Name:	us-gaap_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentAxis=rdn_NonConventionalMortgageLoanMember
Namespace Prefix:
Data Type:	na
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