Note 15 - Subsequent Events (Details) (Smart Home [Member])	Apr. 02, 2012
Smart Home [Member]
Subsequent Event [Line Items]
Number of Transactions Terminated	1
Number Of Transactions Remaining Prior To Termination	2

Number Of Transactions Remaining Prior To Termination

No definition available.

Name:	rdn_NumberOfTransactionsRemainingPriorToTermination
Namespace Prefix:	rdn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant