Note 13 - Statutory Information Risk To Capital Calculation (Details) $ in Millions		3 Months Ended	12 Months Ended
		Mar. 31, 2016 USD ($) state	Dec. 31, 2015 USD ($)
Risk to Capital Line Items [Line Items]
Risk To Capital Ratio, Regulatory Maximum		25
Radian Guaranty [Member]
Risk to Capital Line Items [Line Items]
Percentage of New Insurance Written Attributable To States With Statutory Or Regulatory Risk Based Capital Requirements		56.00%	55.80%
RIF, net (1)	[1]	$ 33,376.7	$ 36,396.1
Common stock and paid-in capital		2,041.4	2,041.4
Surplus Note		325.0	325.0
Unassigned deficit		(640.2)	(679.9)
Statutory policyholders’ surplus		1,726.2	1,686.5
Contingency reserve		949.3	860.9
Statutory capital		$ 2,675.5	$ 2,547.4
Risk-to-capital		12.5	14.3
Statutory Accounting Practices, Statutory Net Income Amount		$ 122.7
State Insurance Regulations [Member]
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 [Member] | Minimum [Member]
Risk to Capital Line Items [Line Items]
Capital Required for Capital Adequacy		$ 1.0
Non RBC States [Member] | Maximum [Member]
Risk to Capital Line Items [Line Items]
Capital Required for Capital Adequacy		$ 5.0

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