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

Represents the percentage of NIW that is able to be ceded under an entity's quota share arrangements.

+ References

No definition available.

+ Details

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

- Definition

The carrying amount for commissions, taxes and other expenses that were incurred but unpaid as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.15)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_AccruedLiabilitiesForCommissionsExpenseAndTaxes
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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 (c)(2)
-URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547

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)(3)
-URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547

+ 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

- Definition

Ratio of non-life losses and loss expenses to non-life net premiums earned.

+ References

No definition available.

+ Details

Name:	us-gaap_LossRatio
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Details

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

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
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:

Note 7 - Reinsurance Reinsurance Transactions (Details) - Reinsurer Concentration Risk [Member] - Radian Guaranty [Member] $ in Thousands	3 Months Ended		12 Months Ended	15 Months Ended	24 Months Ended	33 Months Ended
	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2015	Mar. 31, 2013	Dec. 31, 2017 USD ($)	Dec. 31, 2015	Dec. 31, 2012 transaction
Quota Share Reinsurance Transactions [Member]
Ceded Credit Risk [Line Items]
First Lien Primary Mortgage Insurance Risk In Force Ceded	$ 2,018,468	$ 2,575,060
Ceded Premiums Written	7,962	10,596
Ceded Premiums Earned	11,325	14,786
Accrued Liabilities for Commissions, Expense and Taxes	2,270	3,165
Fees and Commissions	$ 5,739	6,664
Number of Quota Share Reinsurance Agreements \| transaction							2
Ceded Insurance Commission Percentage	30.00%		35.00%
Single Premium QSR Transaction [Member]
Ceded Credit Risk [Line Items]
First Lien Primary Mortgage Insurance Risk In Force Ceded	$ 3,308,057	0
Ceded Premiums Written	197,593	0
Ceded Premiums Earned	5,994	0
Accrued Liabilities for Commissions, Expense and Taxes	50,932	0
Fees and Commissions	$ 3,032	$ 0
Ceded Insurance Commission Percentage	25.00%
Percentage of NIW Able to be Ceded under QSA				20.00%		35.00%
Scenario, Forecast [Member] \| Single Premium QSR Transaction [Member]
Ceded Credit Risk [Line Items]
Ceded Premiums Written					$ 195,000
Percentage of NIW Able to be Ceded under QSA					35.00%
Maximum [Member] \| Single Premium QSR Transaction [Member]
Ceded Credit Risk [Line Items]
Loss Ratio	55.00%