Note 4 - Fair Value of Financial Instruments Fair Value, Measurement Inputs Disclosure (Details) (USD $)	6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013	Dec. 31, 2013
Corporate collateralized debt obligations (CDO's)[Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	$ 1,545,000
Non Corporate Collateralized Debt Obligations And Other Derivative Transactions [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	(132,591,000)
Base Correlation Model Valuation Technique [Member] | Corporate collateralized debt obligations (CDO's)[Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	1,500,000	[1]		(1,400,000)	[1]
Base Correlation Model Valuation Technique [Member] | Minimum [Member] | Corporate collateralized debt obligations (CDO's)[Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, Average Credit Spread	0.10%			0.10%
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, CDS Spread Percent	0.80%	[2]		0.80%	[2]
Base Correlation Model Valuation Technique [Member] | Maximum [Member] | Corporate collateralized debt obligations (CDO's)[Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, Average Credit Spread	0.60%			0.90%
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, CDS Spread Percent	3.80%	[2]		4.30%	[2]
Base Correlation Model Valuation Technique [Member] | Weighted Average [Member] | Corporate collateralized debt obligations (CDO's)[Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, Correlation Factor	85.00%			85.00%
Discounted Cash Flow Valuation Technique [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	19,500,000	[1]		18,700,000	[1]
Discounted Cash Flow Valuation Technique [Member] | Other investments | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	82,300,000	[1]		81,000,000	[1]
Discounted Cash Flow Valuation Technique [Member] | Asset-backed Securities, Securitized Loans and Receivables [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Investments, Fair Value Disclosure	74,400,000	[1]
Discounted Cash Flow Valuation Technique [Member] | Collateralized Debt Obligation of Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	(36,700,000)	[1]		(67,800,000)	[1]
Discounted Cash Flow Valuation Technique [Member] | TruPs Collateralized Debt Obligation [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	(22,200,000)	[1]		(43,900,000)	[1]
Discounted Cash Flow Valuation Technique [Member] | TruPs-Related VIE [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Variable Interest Entity, Consolidated, Fair Value, Net Asset (Liability)	(52,200,000)	[1]		(68,400,000)	[1]
Discounted Cash Flow Valuation Technique [Member] | NIMS VIEs [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Variable Interest Entity, Consolidated, Fair Value, Net Asset (Liability)	(3,200,000)	[1]		(2,800,000)	[1]
Discounted Cash Flow Valuation Technique [Member] | Minimum [Member] | Asset-backed Securities, Securitized Loans and Receivables [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, Discount Rate	3.50%
Discounted Cash Flow Valuation Technique [Member] | Minimum [Member] | Collateralized Debt Obligation of Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, CDS Spread Percent	0.80%	[2]		0.80%	[2]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, Correlation Factor Related to Vintage and Credit Rating				72.00%
Discounted Cash Flow Valuation Technique [Member] | Minimum [Member] | TruPs Collateralized Debt Obligation [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, CDS Spread Percent	0.80%	[2]		0.80%	[2]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, Probability of Paying a Conditional Liquidity Claim	0.20%			1.10%
Discounted Cash Flow Valuation Technique [Member] | Maximum [Member] | Asset-backed Securities, Securitized Loans and Receivables [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, Discount Rate	5.70%
Discounted Cash Flow Valuation Technique [Member] | Maximum [Member] | Collateralized Debt Obligation of Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, CDS Spread Percent	3.80%	[2]		4.30%	[2]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, Correlation Factor Related to Vintage and Credit Rating				85.00%
Discounted Cash Flow Valuation Technique [Member] | Maximum [Member] | TruPs Collateralized Debt Obligation [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, CDS Spread Percent	3.80%	[2]		4.30%	[2]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, Probability of Paying a Conditional Liquidity Claim	10.00%			12.40%
Discounted Cash Flow Valuation Technique [Member] | Weighted Average [Member] | US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, Discount Rate	12.30%			12.30%
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, Expected Loss Rate	11.10%			11.10%
Discounted Cash Flow Valuation Technique [Member] | Weighted Average [Member] | Other investments | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, Discount Rate	0.80%			1.20%
Discounted Cash Flow Valuation Technique [Member] | Weighted Average [Member] | Collateralized Debt Obligation of Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, Correlation Factor Related to Vintage and Credit Rating	80.00%
Discounted Cash Flow Valuation Technique [Member] | Weighted Average [Member] | TruPs Collateralized Debt Obligation [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, Principal Recovery Rate	75.00%			75.00%
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, Principal Recovery Rate Using Distressed Pricing Scenario	65.00%			65.00%
Discounted Cash Flow Valuation Technique [Member] | Weighted Average [Member] | TruPs-Related VIE [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, Discount Rate	8.60%			13.10%
Discounted Cash Flow Valuation Technique [Member] | Weighted Average [Member] | NIMS VIEs [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, CDS Spread Percent	7.00%	[2]		7.90%	[2]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, NIMS Spread	42.60%			43.80%
Risk-Based Model Valuation Technique [Member] | Non Corporate Collateralized Debt Obligations And Other Derivative Transactions [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	$ (84,200,000)	[1]		$ (119,400,000)	[1]
Risk-Based Model Valuation Technique [Member] | Minimum [Member] | Non Corporate Collateralized Debt Obligations And Other Derivative Transactions [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, CDS Spread Percent	0.80%	[2]		0.80%	[2]
Risk-Based Model Valuation Technique [Member] | Maximum [Member] | Non Corporate Collateralized Debt Obligations And Other Derivative Transactions [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value, Measurement with Unobservable Inputs, Additional Disclosure, CDS Spread Percent	3.80%	[2]		4.30%	[2]
Fair Value Assumptions, Expected Term	20 years		20 years
Risk-Based Model Valuation Technique [Member] | Less Than [Member] | Minimum [Member] | Non Corporate Collateralized Debt Obligations And Other Derivative Transactions [Member] | Fair Value, Inputs, Level 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Assumptions, Expected Term	1 year		1 year

[1] Excludes certain assets and liabilities for which we do not develop quantitative unobservable inputs. The fair value estimates for these assets and liabilities are developed using third-party pricing information, generally without adjustment.

[2] Represents the range of our CDS spread that a typical market participant might use in the valuation analysis based on the remaining term of the investment.