Note 15 - Accumulated Other Comprehensive Income (Loss) Rollforward of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jun. 30, 2018	Dec. 31, 2017
Other Comprehensive Income, Net of Tax [Abstract]
AOCI, Net of Tax, Balance at beginning of period				$ 23,085
Unrealized holding gains (losses) arising during the period		$ (5,341)	$ 6,239	(93,788)	$ 33,845
Less: Reclassification adjustment for net gains (losses) included in net income (loss)		(4,044)	111	(8,512)	(2,687)
Unrealized foreign currency translation adjustments		0	28	3	136
Other comprehensive income (loss), net of tax		(1,297)	6,156	(85,273)	36,668
AOCI, Net of Tax, Balance at end of period		(59,240)		(59,240)
Other Comprehensive Income
Other Comprehensive Income, before Tax [Abstract]
AOCI before Tax, Balance at beginning of period		(73,345)	27,878	32,669	(19,063)
AOCI before Tax, Balance adjusted for cumulative effect of adopting accounting standard updates		(73,345)		32,953
Unrealized holding gains (losses) arising during the period		(6,762)	9,598	(118,719)	52,069
Less: Reclassification adjustment for net gains (losses) included in net income	[1]	(5,120)	170	(10,775)	(4,134)
Net unrealized gains (losses) on investments		(1,642)	9,428	(107,944)	56,203
Unrealized foreign currency translation adjustments					205
Unrealized foreign currency translation adjustments		0	39	4
OCI		(1,642)	9,467	(107,940)	56,408
AOCI before Tax, Balance at end of period		(74,987)	37,345	(74,987)	37,345
Other Comprehensive Income, Tax [Abstract]
AOCI, Tax, Balance at beginning of period		(15,402)	9,761	9,584	(6,668)
AOCI, Tax, Balance adjusted for Cumulative Effect of Adopting Accounting Standard Updates		(15,402)		6,920
Unrealized holding gains (losses) arising during the period		(1,421)	3,359	(24,931)	18,224
Less: Reclassification adjustment for net gains (losses) included in net income	[1]	(1,076)	59	(2,263)	(1,447)
Net unrealized gains (losses) on investments		(345)	3,300	(22,668)	19,671
Unrealized foreign currency translation adjustments					69
Unrealized foreign currency translation adjustments		0	11	1
OCI		(345)	3,311	(22,667)	19,740
AOCI Tax, Balance at end of period		(15,747)	13,072	(15,747)	13,072
Other Comprehensive Income, Net of Tax [Abstract]
AOCI, Net of Tax, Balance at beginning of period		(57,943)	18,117	23,085	(12,395)
AOCI, Net of Tax, Balance adjusted for Cumulative Effect of Adopting Accounting Standard Updates		(57,943)		26,033
Unrealized holding gains (losses) arising during the period		(5,341)	6,239	(93,788)	33,845
Less: Reclassification adjustment for net gains (losses) included in net income (loss)	[1]	(4,044)	111	(8,512)	(2,687)
Net unrealized gains (losses) on investments		(1,297)	6,128	(85,276)	36,532
Unrealized foreign currency translation adjustments		0	28	3	136
Other comprehensive income (loss), net of tax		(1,297)	6,156	(85,273)	36,668
AOCI, Net of Tax, Balance at end of period		$ (59,240)	$ 24,273	$ (59,240)	$ 24,273
ASU 2016-01 | Other Comprehensive Income
Other Comprehensive Income, before Tax [Abstract]
AOCI before tax,Cumulative Effect of Adopting an Accounting Standard Update						$ 0	$ 284
Other Comprehensive Income, Tax [Abstract]
AOCI, Tax, Cumulative Effect of Adopting an Accounting Standard Update						0	60
Other Comprehensive Income, Net of Tax [Abstract]
AOCI, Net of Tax, Cumulative Effect of Adopting an Accounting Standard Update, Net of Tax						0	224
ASU 2018-02 | Other Comprehensive Income
Other Comprehensive Income, before Tax [Abstract]
AOCI before tax,Cumulative Effect of Adopting an Accounting Standard Update						0	0
Other Comprehensive Income, Tax [Abstract]
AOCI, Tax, Cumulative Effect of Adopting an Accounting Standard Update						0	(2,724)
Other Comprehensive Income, Net of Tax [Abstract]
AOCI, Net of Tax, Cumulative Effect of Adopting an Accounting Standard Update, Net of Tax						$ 0	$ 2,724

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