Note 15 - Commitments and Contingencies Contract Underwriting (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2013
Contract Underwriting [Line Items]
Losses Paid For Contract Underwriting Remedies	$ 1.6
Provision For Contract Underwriting Expense	1.7
Reserve For Contract Underwriting Obligations	$ 3.8

This concept represents the amount of provision for contract underwriting remedies for the reporting period.

No definition available.

Name:	rdn_ProvisionForContractUnderwritingExpense
Namespace Prefix:	rdn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration