Note 15 - Commitments and Contingencies Contract Underwriting (Details) (Mortgage Insurance Segment, USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2014
Mortgage Insurance Segment
Contract Underwriting [Line Items]
Losses Paid For Contract Underwriting Remedies	$ 0.5
Provision For Contract underwriting Expense	0.2
Reserve For Contract Underwriting Obligations	$ 3.4

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