Note 15 - Statutory Information Statutory Information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Reportable Subsegments [Member]
Statutory Accounting Practices [Line Items]
Restricted Net Assets Held by Consolidated Subsidiaries		$ 3,400.0
Radian Guaranty
Statutory Accounting Practices [Line Items]
Statutory Accounting Practices, Statutory Capital and Surplus, Balance		1,125.9	$ 1,349.7
Statutory Accounting Practices, Dividends Paid with Approval of Regulatory Agency	$ 175.0
Statutory Accounting Practices, Statutory Capital and Surplus, Increase (Decrease)	(175.0)	81.3
Radian Reinsurance [Member]
Statutory Accounting Practices [Line Items]
Capital Contributions	175.0
Statutory Accounting Practices, Statutory Capital and Surplus, Balance		332.1	$ 147.6
Statutory Accounting Practices, Statutory Capital and Surplus, Increase (Decrease)	$ 175.0
Deferred Tax Assets [Member]
Statutory Accounting Practices [Line Items]
Statutory Accounting Practices, Statutory to GAAP, Amount of Reconciling Item		$ (63.2)