Note 13 - Commitments and Contingencies Contract Underwriting (Details) - Mortgage Insurance Segment $ in Millions	12 Months Ended
Dec. 31, 2016 USD ($)
Contract Underwriting [Line Items]
Provision For Contract underwriting Expense	$ 0.2
Reserve For Contract Underwriting Obligations	$ 0.5

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