Note 5 - Investments Unrealized Gain (Loss) on Investments (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	$ 1,196,446	$ 528,660
Available-for-sale Securities	1,179,723	680,258
Available-for-sale Equity Securities, Amortized Cost Basis	573	76,900
Available-for-sale Securities, Equity Securities	881	143,368
Amortized Cost Debt and Equity Securities	1,197,019	605,560
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	4,496	77,231
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	21,792	2,533
US government and agency securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	5,745	5,709
Available-for-sale Securities	5,784	5,751
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	39	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	17,668	17,727
Available-for-sale Securities	18,476	18,910
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	810	1,183
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	2	0
Corporate bonds and notes
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	529,942	277,678
Available-for-sale Securities	517,857	284,408
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	1,850	7,288
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	13,935	558
RMBS
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	158,134	41,467
Available-for-sale Securities	156,532	42,520
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	513	1,053
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	2,115	0
CMBS
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	218,531	57,358
Available-for-sale Securities	213,988	58,234
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	97	876
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	4,640	0
Other ABS
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	243,096	109,420
Available-for-sale Securities	243,045	107,701
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	693	8
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	744	1,727
Foreign government securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	23,330	19,301
Available-for-sale Securities	23,160	19,366
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	186	307
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	356	242
Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Debt Securities, Amortized Cost Basis	1,196,446	528,660
Available-for-sale Securities	1,178,842	536,890
Available-for-sale Debt Securities, Accumulated Gross Unrealized Gain, before Tax	4,188	10,763
Available-for-sale Debt Securities, Accumulated Gross Unrealized Loss, before Tax	21,792	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	881	143,368	[1]
Available-for-sale Equity Securities, Accumulated Gross Unrealized Gain, before Tax	308	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 and Common 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).