Note 15 - Statutory Information Risk To Capital Calculation (Details) $ in Millions		3 Months Ended
		Mar. 31, 2020 USD ($)	Jan. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Radian Guaranty
Risk to Capital Line Items [Line Items]
RIF, net	[1]	$ 49,820.3		$ 44,076.7
Common stock and paid-in capital		1,041.0		1,041.0
Surplus Note		300.0	$ 200.0	100.0
Unassigned earnings (deficit)		(819.8)		(503.3)
Statutory policyholders’ surplus		521.2		637.7
Contingency reserve		3,089.6		2,607.8
Statutory capital		$ 3,610.8		$ 3,245.5
Risk-to-capital		13.8		13.6
Increase (decrease) in Statutory Capital and Surplus		$ 365.3
Statutory Net Income (Loss)		195.5
Statutory Accounting Practices, Statutory Amount Available for Dividend Payments		$ 0.0
Consolidated insurance subsidiaries
Risk to Capital Line Items [Line Items]
Risk-to-capital		12.4		12.3

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