Name:	rdn_IncomeTaxExaminationProposedPenaltiesResultingFromIrsExaminationOfTaxYears2000Through2007
Namespace Prefix:	rdn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Number of Days Company Has to Respond to IRS Office of Appeals Deficiency Notice with payment of assessed tax liabilities, penalties and interest or to petition the US Tax Court to litigate.

No definition available.

Name:	rdn_NumberOfDaysCompanyHasToRespondToIrsOfficeOfAppealsDeficiencyNotice
Namespace Prefix:	rdn_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

This concept represents the proposed Increase an entities tax liability resulting from an IRS examination excluding interest and penalties.

No definition available.

Name:	rdn_ProposedIncreaseToTaxLiabilityResultingFromIRSExaminationOfTaxYears2000Through2007
Namespace Prefix:	rdn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

This concept represents qualified deposits made with the United States Department of Treasury relating to proposed adjustments to the entity's tax losses and deductions based on examinations by the Internal Revenue Department.

No definition available.

Name:	rdn_QualifiedDepositWithUSDepartmentOfTreasuryRelatingToTaxYears2000Through2004
Namespace Prefix:	rdn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Qualified Deposit With The U.S. Department Of Treasury Relating To Tax Years 2005 Through 2007

No definition available.