Note 5 - Fair Value of Financial Instruments Impact of Non-Performance Risk on Fair Value Disclosure (Details) (USD $)				12 Months Ended																			12 Months Ended
	Dec. 31, 2012 contract	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Fair Value, Concentration of Risk, Market Risk Management, Additional Details [Member] basispoint	Dec. 31, 2011 Fair Value, Concentration of Risk, Market Risk Management, Additional Details [Member] basispoint	Dec. 31, 2010 Fair Value, Concentration of Risk, Market Risk Management, Additional Details [Member] basispoint	Dec. 31, 2009 Fair Value, Concentration of Risk, Market Risk Management, Additional Details [Member] basispoint	Dec. 31, 2012 Corporate Collateralized Debt Obligations [Member]	Dec. 31, 2011 Corporate Collateralized Debt Obligations [Member]	Dec. 31, 2012 Non Corporate Collateralized Debt Obligations And Other Derivative Transactions [Member]		Dec. 31, 2011 Non Corporate Collateralized Debt Obligations And Other Derivative Transactions [Member]		Dec. 31, 2012 NIMS Related [Member]		Dec. 31, 2011 NIMS Related [Member]		Dec. 31, 2011 Committed Preferred Securities CPS	Dec. 31, 2012 NIMS VIEs [Member]		Dec. 31, 2011 NIMS VIEs [Member]		Dec. 31, 2012 NIMS VIEs [Member] Fair Value, Inputs, Level 3	Dec. 31, 2011 NIMS VIEs [Member] Fair Value, Inputs, Level 3	Dec. 31, 2012 Consolidated Financial Guaranty Insurance Contracts [Member]		Dec. 31, 2011 Consolidated Financial Guaranty Insurance Contracts [Member]		Dec. 31, 2012 Consolidated Financial Guaranty Insurance Contracts [Member] Fair Value, Inputs, Level 3	Dec. 31, 2012 Collateralized Debt Obligations [Member]
Five Year CDS Spread Details [Abstract]
Radian Group's five year CDS Spread (in basis points)				913	2,732	465	1,530
Number of Years for CDS Spread Related to Non Performance Risk In Fair Value Disclosure				5 years
Derivative Liability, Fair Value, Gross Liability	$ 800,900,000	$ 2,010,200,000						$ 98,800,000	$ 463,100,000	$ 689,100,000	[1]	$ 1,529,700,000	[1]	$ 13,000,000	[2]	$ 17,400,000	[2]
Derivative Credit Risk Valuation Adjustment, Derivative Liabilities	615,600,000	1,872,900,000						101,600,000	458,000,000	509,300,000	[1]	1,405,300,000	[1]	4,700,000	[2]	9,600,000	[2]
Derivative liabilities, net	185,300,000	137,300,000						(2,800,000)	5,100,000	179,800,000	[1]	124,400,000	[1]	8,300,000	[2]	7,800,000	[2]
Market View Of The Probability That Registrant Will Default In The Next Five Years				47.70%	83.50%
Number Of Years In Which The Market Believes Radian Group Will Default				5 years
Change in Impact of Non Performance Risk on Fair Value of Financial Instruments				1,300,000,000																			5,200,000	10,200,000
VIE debt - at fair value	108,858,000	228,240,000	520,114,000															0	9,875,000		9,450,000				98,983,000		218,790,000		99,000,000
Fair Value Inputs [Abstract]
Percent of Aggregate Net Par Outstanding for Corporate CDOs Whose Contractual Premiums are Subject to Change Due to Right of Termination																														80.00%
Percent of Aggregate Net Par Outstanding Corporate CDOs Subject to Termination With Fair Value Cap																														37.00%
Percent of Corporate CDO Deals With Minimum Fair Premium Amount																														32.00%
Percent of Aggregate Net Par Outstanding for Non Corporate CDOs Whose Contractual Premiums are Subject to Change Due to Right of Termination																														87.00%
Percent of Aggregate Net Par Outstanding Non Corporate CDOs Subject to Termination With Fair Value Cap																														34.00%
Number of Financial Guarantee Insurance Contracts That Require Posting of Collateral	0
Maximum exposure (1)																			14,061,000	[3]	18,515,000	[3]	13,500,000	18,000,000	120,939,000	[4]	579,988,000	[4]	120,900,000
VIE Other Assets	99,337,000	105,903,000																											99,200,000
Variable Interest Entity Accounts Payable And Other Liabilities	$ 366,000	$ 530,000																											$ 200,000

[1] Includes the net fair value liability recorded within derivative assets and derivative liabilities and the net fair value liabilities included in our consolidated VIEs.

[2] Includes NIMS VIE debt and NIMS derivative assets.

[3] The difference between the carrying amounts of the net asset/liability position and maximum exposure related to VIEs is primarily due to the difference between the face amount of the obligation and the recorded fair values, which include an adjustment for our non-performance risk. The maximum exposure is based on the net par amount of our insured obligation as of the reporting date.

[4] The difference between the carrying amounts of the net asset/liability position and maximum exposure related to VIEs is primarily due to the difference between the face amount of the obligation and the recorded fair values, which include an adjustment for our non-performance risk, as applicable. For those VIEs that have recourse to our general credit, the maximum exposure is based on the net par amount of our insured obligation. For any VIEs that do not have recourse to our general credit, the maximum exposure is generally based on the recorded net assets of the VIE, as of the reporting date.