Note 16 - Statutory Information - Statutory Information (Details) $ in Thousands		9 Months Ended
	Sep. 22, 2021 USD ($)	Sep. 30, 2021 USD ($) state	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Statutory Accounting Practices [Line Items]
Risk To Capital Ratio, Regulatory Maximum		25
State Insurance Regulations
Statutory Accounting Practices [Line Items]
Number Of States That Have A Statutory Or Regulatory Risk Based Capital Requirement | state		16
Radian Guaranty
Statutory Accounting Practices [Line Items]
Statutory Net Income (Loss)		$ 516,866	$ 260,175
Statutory Accounting Practices, Statutory Capital and Surplus, Balance		646,923		$ 481,484
Statutory Accounting Practices, Contingency Reserve		$ 3,800,000
Risk To Capital Ratio		11.4		12.7
Radian Reinsurance
Statutory Accounting Practices [Line Items]
Statutory Net Income (Loss)		$ 8,765	30,358
Statutory Accounting Practices, Statutory Capital and Surplus, Balance		328,430		$ 360,704
Return of capital	$ 36,000
Other MI Companies
Statutory Accounting Practices [Line Items]
Statutory Net Income (Loss)		777	929
Statutory Accounting Practices, Statutory Capital and Surplus, Balance		42,715		41,327
Radian Title Insurance
Statutory Accounting Practices [Line Items]
Statutory Net Income (Loss)		4,777	$ 1,399
Statutory Accounting Practices, Statutory Capital and Surplus, Balance		34,342		$ 28,849
Consolidated insurance subsidiaries
Statutory Accounting Practices [Line Items]
Restricted Net Assets Held by Consolidated Subsidiaries		$ 4,600,000