Note 4 - Fair Value of Financial Instruments Fair Value Assets Liabilities by Hierarchy Level (Details) (USD $)	Sep. 30, 2013		Dec. 31, 2012
Fair Value by Hierarchy Level [Line Items]
Total held to maturity amortized cost	$ 428,000		$ 679,000
Derivative assets	20,844,000		13,609,000
Derivative liabilities	344,870,000		266,873,000
VIE debt—at fair value	104,218,000		108,858,000
Fixed-maturities held to maturity	421,000		676,000
Variable Interest Entity, Primary Beneficiary [Member]
Fair Value by Hierarchy Level [Line Items]
Number Of Consolidated Other Financial Guaranty Transactions	2
Financial Guarantee Insurance Product Line [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Value by Hierarchy Level [Line Items]
VIE debt—at fair value	93,109,000		98,983,000
NIMS VIEs [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Value by Hierarchy Level [Line Items]
Derivative assets	1,577,000		1,585,000
VIE debt—at fair value	11,109,000		9,875,000
Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	4,975,200,000	[1]	5,103,000,000	[2]
Derivative assets	20,900,000		13,600,000
Other Assets	93,200,000	[3]	99,200,000	[3]
Total Assets at Fair Value	5,089,300,000		5,215,800,000
Derivative liabilities	344,900,000		266,900,000
VIE debt—at fair value	104,200,000	[4]	108,900,000	[5]
Total Liabilities at Fair Value	449,100,000		375,800,000
Fair Value, Measurements, Recurring | Reported Value Measurement [Member]
Fair Value by Hierarchy Level [Line Items]
Total held to maturity amortized cost	400,000		700,000
Other invested assets fair value disclosure	49,600,000		48,700,000
Fair Value, Measurements, Recurring | US government and agency securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	1,290,900,000		571,600,000
Fair Value, Measurements, Recurring | State and municipal obligations
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	635,700,000		688,000,000
Fair Value, Measurements, Recurring | Money market instruments
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	548,100,000		638,000,000
Fair Value, Measurements, Recurring | Corporate bonds and notes
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	1,104,500,000		1,373,600,000
Fair Value, Measurements, Recurring | RMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	603,600,000		663,400,000
Fair Value, Measurements, Recurring | CMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	294,800,000		237,300,000
Fair Value, Measurements, Recurring | Other ABS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	204,200,000		254,100,000
Fair Value, Measurements, Recurring | Foreign government securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value			117,700,000
Fair Value, Measurements, Recurring | Hybrid securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	400,000		211,900,000
Fair Value, Measurements, Recurring | Equity securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	210,300,000	[6]	265,900,000	[6]
Fair Value, Measurements, Recurring | Other investments
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	82,700,000	[7]	81,500,000	[8]
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	1,538,800,000	[1]	874,700,000	[2]
Derivative assets	0		0
Other Assets	0	[3]	0	[3]
Total Assets at Fair Value	1,538,800,000		874,700,000
Derivative liabilities	0		0
VIE debt—at fair value	0	[4]	0	[5]
Total Liabilities at Fair Value	0		0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | US government and agency securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	874,000,000		137,800,000
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | State and municipal obligations
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Money market instruments
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	548,100,000		638,000,000
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Corporate bonds and notes
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | RMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | CMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Other ABS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Foreign government securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value			0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Hybrid securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Equity securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	116,700,000	[6]	98,900,000	[6]
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Other investments
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0	[7]	0	[8]
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	3,336,400,000	[1]	4,127,600,000	[2]
Derivative assets	12,000,000		0
Other Assets	0	[3]	0	[3]
Total Assets at Fair Value	3,348,400,000		4,127,600,000
Derivative liabilities	0		0
VIE debt—at fair value	0	[4]	0	[5]
Total Liabilities at Fair Value	0		0
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Trust Preferred Securities [Member]
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	900,000		900,000
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | US government and agency securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	416,900,000		433,800,000
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | State and municipal obligations
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	617,300,000		669,000,000
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Money market instruments
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Corporate bonds and notes
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	1,104,500,000		1,373,600,000
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | RMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	603,600,000		663,400,000
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | CMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	294,800,000		237,300,000
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Other ABS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	203,200,000		252,400,000
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Foreign government securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value			117,700,000
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Hybrid securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	400,000		211,900,000
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Equity securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	93,200,000	[6]	166,000,000	[6]
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Other investments
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	2,500,000	[7]	2,500,000	[8]
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Short Term CDs
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	1,600,000		1,600,000
Fair Value, Inputs, Level 3 | Financial Guarantee Insurance Product Line [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Value by Hierarchy Level [Line Items]
Number Of Consolidated Other Financial Guaranty Transactions	2		2
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	100,000,000	[1]	100,700,000	[2]
Derivative assets	8,900,000		13,600,000
Other Assets	93,200,000	[3]	99,200,000	[3]
Total Assets at Fair Value	202,100,000		213,500,000
Derivative liabilities	344,900,000		266,900,000
VIE debt—at fair value	104,200,000	[4]	108,900,000	[5]
Total Liabilities at Fair Value	449,100,000		375,800,000
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Financial Guarantee Insurance Product Line [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Value by Hierarchy Level [Line Items]
VIE debt—at fair value	93,100,000		99,000,000
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | NIMS VIEs [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Fair Value by Hierarchy Level [Line Items]
VIE debt—at fair value	11,100,000		9,900,000
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | US government and agency securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | State and municipal obligations
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	18,400,000		19,000,000
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Money market instruments
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Corporate bonds and notes
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | RMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | CMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Other ABS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	1,000,000		1,700,000
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Foreign government securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value			0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Hybrid securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Equity securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	400,000	[6]	1,000,000	[6]
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Other investments
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	80,200,000	[7]	79,000,000	[8]
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Lottery Annuities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	500,000		1,000,000
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Consolidated Committed Preferred Custodial Trust Securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	$ 79,700,000		$ 78,000,000

[1] Does not include fixed-maturities held to maturity ($0.4 million) and certain other invested assets ($49.6 million), primarily invested in limited partnerships, accounted for as cost-method investments and not measured at fair value.

[2] Does not include fixed-maturities held to maturity ($0.7 million) and certain other invested assets ($48.7 million), primarily invested in limited partnerships, accounted for as cost-method investments and not measured at fair value.

[3] Primarily comprising manufactured housing loan collateral related to two consolidated financial guaranty VIEs.

[4] Comprising consolidated debt related to NIMS VIEs ($11.1 million) and amounts related to financial guaranty VIEs ($93.1 million).

[5] Comprising consolidated debt related to NIMS VIEs ($9.9 million) and amounts related to financial guaranty VIEs ($99.0 million).

[6] Comprising broadly diversified domestic equity mutual funds included within Level I and various preferred and common stocks invested across numerous companies and industries included within Levels II and III.

[7] Comprising TruPs ($0.9 million) and short-term certificates of deposit (“CDs”) ($1.6 million) included within Level II, and lottery annuities ($0.5 million) and a guaranteed investment contract held by a consolidated VIE ($79.7 million) within Level III.

[8] Comprising TruPs ($0.9 million) and short-term CDs ($1.6 million) included within Level II, and lottery annuities ($1.0 million) and a guaranteed investment contract held by a consolidated VIE ($78.0 million) within Level III.