Note 16 - Statutory Information Risk To Capital Calculation (Details) $ in Millions		9 Months Ended
		Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Radian Guaranty
Risk to Capital Line Items [Line Items]
RIF, net	[1]	$ 40,241.6	$ 36,793.5
Common stock and paid-in capital		1,866.0	1,866.0
Surplus Note		100.0	100.0
Unassigned earnings (deficit)		(708.9)	(765.0)
Statutory policyholders’ surplus		1,257.1	1,201.0
Contingency reserve		1,995.8	1,667.0
Statutory capital		$ 3,252.9	$ 2,868.0
Risk-to-capital		12.4	12.8
Increase (decrease) in Statutory Capital and Surplus		$ 384.9
Statutory Net Income (Loss)		$ 376.3
Consolidated insurance subsidiaries
Risk to Capital Line Items [Line Items]
Risk-to-capital		11.7	12.1

[1] Excludes risk ceded through reinsurance contracts (to third parties and affiliates) and RIF on defaulted loans.