Note 16 - Statutory Information - Statutory Dividend Restrictions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2021
Restricted Net Assets Held by Consolidated Subsidiaries	$ 4,100,000
Radian Guaranty
Statutory Unassigned Negative Surplus	(859,500)
Contingency Reserve	3,400,000	$ 2,600,000
Statutory Accounting Practices, Statutory Capital and Surplus, Additions	200,000	0	$ 0
Statutory Accounting Practices, Statutory Capital and Surplus, Distributions	0	(375,000)	(450,000)
Radian Guaranty | Scenario, Forecast
Statutory Accounting Practices, Statutory Amount Available for Dividend Payments				$ 0
Radian Reinsurance
Statutory Unassigned Negative Surplus	(319,700)
Radian Reinsurance | Scenario, Forecast
Statutory Accounting Practices, Statutory Amount Available for Dividend Payments				$ 36,100
Other MI Companies
Statutory Accounting Practices, Statutory Capital and Surplus, Additions	0	65,200	0
Statutory Accounting Practices, Statutory Capital and Surplus, Distributions	$ (465,000)	$ (14,000)	$ 0