Name:	rdn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentOtherThanOptionsFairValuePerShareAtPeriodEnd
Namespace Prefix:	rdn_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

Share-based Compensation Arrangement by Share-based Payment Award, Vesting Percentage of Total Award, Fourth Anniversary

No definition available.

Name:	rdn_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPercentageOfTotalAwardFourthAnniversary
Namespace Prefix:	rdn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Share-based Compensation Arrangement by Share-based Payment Award, Vesting Percentage of Total Award, Third Anniversary

No definition available.

Name:	rdn_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPercentageOfTotalAwardThirdAnniversary
Namespace Prefix:	rdn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

The market value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

No definition available.

Name:	rdn_ShareBasedCompensationArrangementEquityInstrumentsOtherThanOptionsGrantPrice
Namespace Prefix:	rdn_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

This concept represents the maximum contractual term in PnYnMnD format for share-based payment awards.

No definition available.

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

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

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

Number of equity instruments other than options outstanding, including both vested and non-vested instruments.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(i)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901