Note 5 - Investments Unrealized Gain (Loss) on Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	$ 1,507,522	$ 528,660
Available-for-sale Securities	1,497,313	680,258
Available-for-sale Equity Securities, Amortized Cost Basis	573	76,900
Available-for-sale Securities, Equity Securities	985	143,368
Amortized Cost Debt and Equity Securities	1,508,095	605,560
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	9,289	77,231
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	20,071	2,533
US government and agency securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	5,764	5,709
Available-for-sale Securities	5,793	5,751
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	29	48
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	6
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	17,581	17,727
Available-for-sale Securities	18,576	18,910
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	995	1,183
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	0	0
Corporate bonds and notes
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	614,635	277,678
Available-for-sale Securities	606,260	284,408
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	3,753	7,288
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	12,128	558
RMBS
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	208,011	41,467
Available-for-sale Securities	209,028	42,520
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	1,377	1,053
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	360	0
CMBS
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	307,216	57,358
Available-for-sale Securities	305,700	58,234
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	1,533	876
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	3,049	0
Other ABS
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	330,986	109,420
Available-for-sale Securities	328,746	107,701
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	1,088	8
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	3,328	1,727
Foreign government securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	23,329	19,301
Available-for-sale Securities	22,225	19,366
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	102	307
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	1,206	242
Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	1,507,522	528,660
Available-for-sale Securities	1,496,328	536,890
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	8,877	10,763
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	20,071	2,533
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Equity Securities, Amortized Cost Basis	573	76,900	[1]
Available-for-sale Securities, Equity Securities	985	143,368	[1]
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	412	66,468	[1]
Available-for-sale Equity Securities, Accumulated Gross Unrealized Loss, before Tax	$ 0	0	[1]
Private Equity Funds, Domestic [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Equity Securities		143,000
Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Equity Securities		$ 400

[1] Comprising broadly diversified domestic equity mutual funds ($143.0 million fair value) and a preferred stock investment in Freddie Mac ($0.4 million fair value).