Percentage of commissions due to ceded insurance.

No definition available.

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

- Definition

First Lien Primary Mortgage Insurance Risk In Force Ceded

+ References

No definition available.

+ Details

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

- Definition

This concept represents the number of quota share reinsurance agreements the company has entered into with third party reinsurance providers.

+ References

No definition available.

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

Name:	rdn_PercentageOfReinsuranceAbleToBeRecaptured
Namespace Prefix:	rdn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

Name:	rdn_ProfitCommissionEarnedonCededRisk
Namespace Prefix:	rdn_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_CededCreditRiskLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of earned premiums ceded to other entities.

+ References

Reference 1: 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 2: 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 3: 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

Reference 4: 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

+ Details

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

- Definition

Amount of written premiums ceded to other entities.

+ References

Reference 1: 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 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 17

-Article 12

+ Details

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

- Definition

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.

+ References

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

+ Details

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

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_ReinsurerConcentrationRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_CededCreditRiskAxis=rdn_InitialQuotaShareReinsuranceTransactionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CededCreditRiskAxis=rdn_SecondQuotaShareReinsuranceTransactionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Note 7 - Reinsurance Reinsurance Transactions (Details) - Reinsurer Concentration Risk [Member] - Radian Guaranty [Member] $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Dec. 31, 2014	Dec. 31, 2012 transaction
Ceded Credit Risk [Line Items]
Number of Quota Share Reinsurance Agreements \| transaction						2
Initial Quota Share Reinsurance Transaction [Member]
Ceded Credit Risk [Line Items]
Ceded Premiums Written	$ 3,437	$ 4,668	$ 11,326	$ 15,018
Ceded Premiums Earned	5,068	6,578	17,510	20,188
Fees and Commissions	745	1,166	$ 2,453	3,754
Ceded Insurance Commission Percentage			20.00%		25.00%
First Lien Primary Mortgage Insurance Risk In Force Ceded	900,000		$ 900,000
Percentage of Ceded Insurance Subjected to Change in Commission Percentage			66.70%
Initial Quota Share Reinsurance Transaction [Member] \| Maximum [Member]
Ceded Credit Risk [Line Items]
First Lien Primary Mortgage Insurance Risk In Force Ceded	1,600,000		$ 1,600,000
Second Quota Share Reinsurance Transaction [Member]
Ceded Credit Risk [Line Items]
Ceded Premiums Written	5,029	9,082	11,953	24,447
Ceded Premiums Earned	7,135	7,699	18,942	21,481
Fees and Commissions	$ 1,998	$ 3,179	$ 6,437	$ 8,557
Percentage of Ceded Insurance Subjected to Change in Commission Percentage	50.00%		50.00%
First Lien Primary Mortgage Insurance Risk In Force Ceded	$ 1,400,000		$ 1,400,000
Profit Commission Earned on Ceded Risk	700		6,500
Second Quota Share Reinsurance Transaction [Member] \| Maximum [Member]
Ceded Credit Risk [Line Items]
First Lien Primary Mortgage Insurance Risk In Force Ceded	$ 1,600,000		$ 1,600,000