Note 4 - Fair Value of Financial Instruments Fair Value Assets Liabilities by Hierarchy Level (Details) (USD $)	Jun. 30, 2014		Dec. 31, 2013		Jun. 30, 2013
Fair Value by Hierarchy Level [Line Items]
Held-to-maturity Securities	$ 50,000		$ 358,000
Derivative Assets	22,033,000		16,642,000
Derivative liabilities	200,227,000		307,185,000		350,576,000
VIE debt—at fair value	93,631,000		94,645,000		106,767,000
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value by Hierarchy Level [Line Items]
Held-to-maturity Securities	100,000		400,000
Other Invested Assets, Carrying Amount	40,600,000		47,400,000
Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	4,907,100,000	[1]	4,883,400,000	[2]
Derivative Assets	22,000,000		16,600,000
Other Assets	90,400,000	[3]	91,900,000	[3]
Total Assets at Fair Value	5,019,500,000		4,991,900,000
Derivative liabilities	200,200,000		307,200,000
VIE debt—at fair value	93,600,000	[4]	94,600,000	[5]
Total Liabilities at Fair Value	293,800,000		401,800,000
US government and agency securities | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	1,353,500,000		1,157,900,000
State and municipal obligations | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	635,400,000		621,000,000
Money market instruments | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	661,800,000		672,600,000
Corporate bonds and notes | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	1,063,200,000		1,036,600,000
RMBS | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	296,400,000		560,400,000
CMBS | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	278,600,000		288,900,000
Other ABS | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	251,600,000		195,800,000
Foreign government securities | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	49,200,000		40,700,000
Equity securities | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	232,500,000	[6]	225,800,000	[7]
Other investments | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	84,900,000	[8]	83,700,000	[9]
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	1,763,400,000	[1]	1,555,900,000	[2]
Derivative Assets	0		0
Other Assets	0	[3]	0	[3]
Total Assets at Fair Value	1,763,400,000		1,555,900,000
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 | US government and agency securities | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	965,500,000		755,000,000
Fair Value, Inputs, Level 1 | State and municipal obligations | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 1 | Money market instruments | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	661,800,000		672,600,000
Fair Value, Inputs, Level 1 | Corporate bonds and notes | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 1 | RMBS | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 1 | CMBS | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 1 | Other ABS | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 1 | Foreign government securities | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 1 | Equity securities | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	136,100,000	[6]	128,300,000	[7]
Fair Value, Inputs, Level 1 | Other investments | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0	[8]	0	[9]
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	2,967,000,000	[1]	3,226,000,000	[2]
Derivative Assets	15,600,000		10,300,000
Other Assets	0	[3]	0	[3]
Total Assets at Fair Value	2,982,600,000		3,236,300,000
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 | US government and agency securities | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	388,000,000		402,900,000
Fair Value, Inputs, Level 2 | State and municipal obligations | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	615,900,000		602,300,000
Fair Value, Inputs, Level 2 | Money market instruments | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 2 | Corporate bonds and notes | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	1,063,200,000		1,036,600,000
Fair Value, Inputs, Level 2 | RMBS | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	296,400,000		560,400,000
Fair Value, Inputs, Level 2 | CMBS | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	278,600,000		288,900,000
Fair Value, Inputs, Level 2 | Other ABS | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	177,200,000		194,900,000
Fair Value, Inputs, Level 2 | Foreign government securities | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	49,200,000		40,700,000
Fair Value, Inputs, Level 2 | Equity securities | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	96,400,000	[6]	97,100,000	[7]
Fair Value, Inputs, Level 2 | Other investments | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	2,100,000	[8]	2,200,000	[9]
Fair Value, Inputs, Level 2 | Trust Preferred Securities [Member] | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	500,000		600,000
Fair Value, Inputs, Level 2 | Short Term CDs | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	1,600,000		1,600,000
Fair Value, Inputs, Level 3
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	176,700,000	[1]	101,500,000	[2]
Derivative Assets	6,400,000		6,300,000
Other Assets	90,400,000	[3]	91,900,000	[3]
Total Assets at Fair Value	273,500,000		199,700,000
Derivative liabilities	200,200,000		307,200,000
VIE debt—at fair value	93,600,000	[4]	94,600,000	[5]
Total Liabilities at Fair Value	293,800,000		401,800,000
Total Level III Assets	5.40%		4.00%
Total Level III Liabilities	100.00%		100.00%
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | NIMS VIEs [Member]
Fair Value by Hierarchy Level [Line Items]
VIE debt—at fair value	3,200,000		2,800,000
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Consolidated Financial Guaranty Insurance Contracts [Member]
Fair Value by Hierarchy Level [Line Items]
VIE debt—at fair value	90,400,000		91,800,000
Fair Value, Inputs, Level 3 | US government and agency securities | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 3 | State and municipal obligations | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	19,500,000		18,700,000
Fair Value, Inputs, Level 3 | Money market instruments | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 3 | Corporate bonds and notes | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 3 | RMBS | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 3 | CMBS | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 3 | Other ABS | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	74,400,000		900,000
Fair Value, Inputs, Level 3 | Foreign government securities | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0		0
Fair Value, Inputs, Level 3 | Equity securities | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0	[6]	400,000	[7]
Fair Value, Inputs, Level 3 | Other investments | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	82,800,000	[8]	81,500,000	[9]
Fair Value, Inputs, Level 3 | Trust Preferred Securities [Member] | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	200,000		200,000
Fair Value, Inputs, Level 3 | Lottery Annuities | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	300,000		300,000
Fair Value, Inputs, Level 3 | Guaranteed Investment Contract Held by a Consolidated VIE [Member] | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	$ 82,300,000		$ 81,000,000

[1] Does not include fixed-maturities held to maturity ($0.1 million) and certain other invested assets ($40.6 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 ($0.4 million) and certain other invested assets ($47.4 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 ($3.2 million) and financial guaranty VIEs ($90.4 million).

[5] Comprising consolidated debt related to NIMS VIEs ($2.8 million) and financial guaranty VIEs ($91.8 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 Level II.

[7] 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.

[8] Comprising TruPs ($0.5 million) and short-term certificates of deposit (“CDs”) ($1.6 million) included within Level II and lottery annuities ($0.3 million), TruPs ($0.2 million), and a guaranteed investment contract held by a consolidated VIE ($82.3 million) within Level III.

[9] Comprising TruPs ($0.6 million) and short-term CDs ($1.6 million ) included within Level II and lottery annuities ($0.3 million), TruPs ($0.2 million), and a guaranteed investment contract held by a consolidated VIE ($81.0 million) within Level III.