Note 15 - Accumulated Other Comprehensive Income Rollforward of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Other Comprehensive Income, Net of Tax [Abstract]
AOCI, Net of Tax, beginning balance		$ 23,085
Unrealized holding gains (losses) arising during the period		(60,643)	$ 7,367
Less: Reclassification adjustment for net gains (losses) included in net income (loss)		(3,132)	(1,631)
Unrealized foreign currency translation adjustments		3	34
Other comprehensive income (loss), net of tax		(54,560)	9,032
AOCI, Net of Tax, ending balance		(31,475)
Other Comprehensive Income
Other Comprehensive Income, before Tax [Abstract]
AOCI before Tax, Attributable to Parent, beginning balance		32,669	(19,063)
Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax		(76,763)	11,334
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax	[1]	(3,964)	(2,509)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax		(72,799)	13,843
Net foreign currency translation adjustments, before tax		4	52
Other comprehensive income, before tax		(72,511)	13,895
AOCI before Tax, Attributable to Parent, ending balance		(39,842)	(5,168)
Other Comprehensive Income, Tax [Abstract]
AOCI, Tax, beginning balance		9,584	(6,668)
Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax		(16,120)	3,967
Less: Reclassification adjustment for net (losses) gains included in net income, tax	[1]	(832)	(878)
Other Comprehensive Income (Loss), Available-for-sale Securities, Tax		(15,288)	4,845
Net foreign currency translation adjustments, tax		1	18
Other Comprehensive Income, Tax		(17,951)	4,863
AOCI Tax, ending balance		(8,367)	(1,805)
Other Comprehensive Income, Net of Tax [Abstract]
AOCI, Net of Tax, beginning balance		23,085	(12,395)
Unrealized holding gains (losses) arising during the period		(60,643)	7,367
Less: Reclassification adjustment for net gains (losses) included in net income (loss)	[1]	(3,132)	(1,631)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent		(57,511)	8,998
Unrealized foreign currency translation adjustments		3	34
Other comprehensive income (loss), net of tax		(54,560)	9,032
AOCI, Net of Tax, ending balance		(31,475)	$ (3,363)
Accounting Standards Update 2016-01 [Member] | Other Comprehensive Income
Other Comprehensive Income, before Tax [Abstract]
Other Comprehensive Income (Loss), Cumulative Effect of Adopting an Accounting Standard Update, Before Tax		284
Other Comprehensive Income, Tax [Abstract]
Other Comprehensive Income (Loss), Cumulative Effect of Adopting an Accounting Standard Update, Tax		60
Other Comprehensive Income, Net of Tax [Abstract]
Cumulative effect of adopting the accounting standard update for financial instruments		224
Other Comprehensive Income (Loss), Cumulative Effect of Adopting an Accounting Standard Update, Before Tax		284
Other Comprehensive Income (Loss), Cumulative Effect of Adopting an Accounting Standard Update, Tax		60
Other Comprehensive Income (Loss), Cumulative Effect of Adopting an Accounting Standard Update, Net of Tax		224
ASU 2018-02 [Member] | Other Comprehensive Income
Other Comprehensive Income, before Tax [Abstract]
Other Comprehensive Income (Loss), Cumulative Effect of Adopting an Accounting Standard Update, Before Tax		0
Other Comprehensive Income, Tax [Abstract]
Other Comprehensive Income (Loss), Cumulative Effect of Adopting an Accounting Standard Update, Tax		(2,724)
Other Comprehensive Income, Net of Tax [Abstract]
Cumulative effect of adopting the accounting standard update for financial instruments		2,724
Other Comprehensive Income (Loss), Cumulative Effect of Adopting an Accounting Standard Update, Before Tax		0
Other Comprehensive Income (Loss), Cumulative Effect of Adopting an Accounting Standard Update, Tax		(2,724)
Other Comprehensive Income (Loss), Cumulative Effect of Adopting an Accounting Standard Update, Net of Tax		$ 2,724

[1] Included in net gains (losses) on investments and other financial instruments on our consolidated statements of operations.