Statutory Information - Statutory Information (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Radian Guaranty
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	$ 577,578	$ 348,307
Statutory policyholders' surplus	572,349		$ 778,148
Radian Reinsurance
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	892	7,418
Statutory policyholders' surplus	324,051		327,118
Other mortgage subsidiaries
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	1,082	629
Statutory policyholders' surplus	15,713		14,524
Radian Title Insurance
Statutory Accounting Practices [Line Items]
Statutory net income (loss)	1,964	$ 2,623
Statutory policyholders' surplus	$ 38,555		$ 36,599

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.

+ Details

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

- Definition

The amount of statutory capital and surplus (stockholders' equity) as of the balance sheet date using prescribed or permitted statutory accounting practices (rather than GAAP, if different) of the state or country.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(23)(c))
-URI https://asc.fasb.org/extlink&oid=126734703&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=6486098&loc=d3e24708-158529

+ Details

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

- Definition

Amount of net income for the period determined using accounting principles prescribed or permitted by insurance regulators.

+ References

+ Details

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

- Details

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

- Details

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

- Details

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

- Details

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