Note 15 - Statutory Information Risk To Capital Calculation (Details) $ in Millions		1 Months Ended	9 Months Ended
		Apr. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Radian Guaranty
Risk to Capital Line Items [Line Items]
RIF, net	[1]		$ 43,484.8	$ 40,711.3
Common stock and paid-in capital			1,041.0	1,416.0
Surplus Note			100.0	100.0
Unassigned earnings (deficit)			(553.5)	(701.9)
Statutory policyholders’ surplus			587.5	814.1
Contingency reserve			2,475.9	2,109.9
Statutory capital			$ 3,063.4	$ 2,924.0
Risk-to-capital			14.2	13.9
Increase (decrease) in Statutory Capital and Surplus			$ 139.4
Statutory Net Income (Loss)			$ 525.5
Statutory Accounting Practices, Dividends Paid with Approval of Regulatory Agency		$ 375.0
Consolidated insurance subsidiaries
Risk to Capital Line Items [Line Items]
Risk-to-capital			12.9	12.8
Extraordinary Distribution | Radian Guaranty
Risk to Capital Line Items [Line Items]
Increase (decrease) in Statutory Capital and Surplus			$ (375.0)

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