Note 18 - Statutory Information Statutory Capital Requirements (Details) $ in Millions		Dec. 31, 2019 USD ($) state	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Risk to Capital Line Items [Line Items]
Risk To Capital Ratio, Regulatory Maximum		25
Radian Guaranty
Risk to Capital Line Items [Line Items]
Net Risk In Force	[1]	$ 44,076.7	$ 40,711.3
Common stock and paid-in capital		1,041.0	1,416.0
Surplus Note		100.0	100.0
Unassigned earnings (deficit)		(503.3)	(701.9)
Statutory Accounting Practices, Statutory Capital and Surplus, Balance		637.7	814.1	$ 1,201.0
Contingency reserve		2,607.8	2,109.9	$ 1,667.0
Statutory Accounting Practice, Statutory Position		$ 3,245.5	$ 2,924.0
Risk-to-capital		13.6	13.9
State Insurance Regulations
Risk to Capital Line Items [Line Items]
Number Of States That Have A Statutory Or Regulatory Risk Based Capital Requirement | state		16
Non RBC States | Minimum
Risk to Capital Line Items [Line Items]
Capital Required for Capital Adequacy		$ 1.0
Non RBC States | Maximum
Risk to Capital Line Items [Line Items]
Capital Required for Capital Adequacy		$ 5.0

[1] Excludes risk ceded through all reinsurance programs (including with affiliates) and RIF on defaulted loans.