Name:	rdn_ChangeInPresentValueofEstimatedCreditLossPayments
Namespace Prefix:	rdn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The increase (decrease) during the reporting period in goodwill and intangible assets which includes amortization, impairment, etc.

No definition available.

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

This concept represents the total of net gains/losses on investments, net gains/losses on other financial instruments, and any other gains on financial instruments for the purposes of reconciling net income (loss) from segments to consolidated results.

No definition available.

Name:	rdn_NetGainsLossesonAllFinancialInstruments
Namespace Prefix:	rdn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

This concept represents the adjusted pre-tax operating income (loss) for segment reporting (non GAAP) and only includes the revenue and expense items that management considers in assessing the performance of the segment businesses.

No definition available.

Name:	rdn_OperatingIncomeLossPreTaxNonGAAP
Namespace Prefix:	rdn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 25

-Paragraph 23

-URI http://asc.fasb.org/extlink&oid=34752592&loc=d3e1043-128460

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

Amount of gain (loss) from the difference between the repurchase price of a debt instrument initially issued by the entity and the net carrying amount of the debt at the time of its repurchase.

No definition available.

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

This element represents the income or loss from continuing operations attributable to the economic entity which may also be defined as revenue less expenses from ongoing operations, after income or loss from equity method investments, but before income taxes, extraordinary items, and noncontrolling interest.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 940

-SubTopic 20

-Section 25

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=51673353&loc=d3e41242-110953

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 10

-Article 5

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

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.

No definition available.