Note 18 - Stockholders' Equity - Accumulated Other Comprehensive Income (Details) - USD ($)			3 Months Ended		6 Months Ended
		Jan. 01, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Beginning balance, loss, net of tax		$ 1,973,304,000			$ 1,973,304,000
Ending balance, loss, net of tax			$ 2,064,833,000		2,064,833,000
Reclassification adjustment for stranded tax effects of Tax Cuts and Job Act, tax		515,000
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Beginning balance, loss, net of tax		(1,060,000)	(21,333,000)	$ (1,771,000)	(1,060,000)	$ (1,545,000)
Net unrealized (losses)/gains arising during the period, pre-tax			(3,905,000)	4,786,000	(20,251,000)	3,930,000
Net unrealized (losses)/gains arising during the period, tax			(1,154,000)	2,012,000	(5,986,000)	1,652,000
Net unrealized (losses)/gains arising during the period, net of tax			(2,751,000)	2,774,000	(14,265,000)	2,278,000
Reclassification adjustment for net losses/(gains) included in net income, pre-tax				(3,000)		463,000
Reclassification adjustment for net losses/(gains) included in net income, tax				(1,000)		195,000
Reclassification adjustment for net losses/(gains) included in net income, net of tax				(2,000)		268,000
Total other comprehensive (loss)/income, pre-tax			(3,905,000)	4,783,000	(20,251,000)	4,393,000
Total other comprehensive (loss)/income, tax			(1,154,000)	2,011,000	(5,986,000)	1,847,000
Total other comprehensive (loss)/income, net of tax			(2,751,000)	2,772,000	(14,265,000)	2,546,000
Ending balance, loss, net of tax			(24,084,000)	1,001,000	(24,084,000)	1,001,000
Reclassification adjustment for stranded tax effects of Tax Cuts and Job Act, tax	[1]				200,000
Reclassification adjustment for stranded tax effects of Tax Cuts and Job Act, net of tax	[1]				(200,000)
Total other comprehensive (loss)/income, pre-tax			(3,905,000)	4,783,000	(20,251,000)	4,393,000
Total other comprehensive (loss)/income, tax			(1,154,000)	2,011,000	(5,986,000)	1,847,000
Total other comprehensive (loss)/income, net of tax			(2,751,000)	2,772,000	(14,265,000)	2,546,000
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Beginning balance, loss, net of tax		(1,451,000)	427,000	(1,871,000)	(1,451,000)	(2,170,000)
Net unrealized (losses)/gains arising during the period, pre-tax			1,045,000	(949,000)	4,158,000	(433,000)
Net unrealized (losses)/gains arising during the period, tax			309,000	(399,000)	1,229,000	(182,000)
Net unrealized (losses)/gains arising during the period, net of tax			736,000	(550,000)	2,929,000	(251,000)
Reclassification adjustment for net losses/(gains) included in net income, pre-tax
Reclassification adjustment for net losses/(gains) included in net income, tax
Reclassification adjustment for net losses/(gains) included in net income, net of tax
Total other comprehensive (loss)/income, pre-tax			1,045,000	(949,000)	4,158,000	(433,000)
Total other comprehensive (loss)/income, tax			309,000	(399,000)	1,229,000	(182,000)
Total other comprehensive (loss)/income, net of tax			736,000	(550,000)	2,929,000	(251,000)
Ending balance, loss, net of tax			1,163,000	(2,421,000)	1,163,000	(2,421,000)
Reclassification adjustment for stranded tax effects of Tax Cuts and Job Act, tax	[1]				315,000
Reclassification adjustment for stranded tax effects of Tax Cuts and Job Act, net of tax	[1]				(315,000)
Total other comprehensive (loss)/income, pre-tax			1,045,000	(949,000)	4,158,000	(433,000)
Total other comprehensive (loss)/income, tax			309,000	(399,000)	1,229,000	(182,000)
Total other comprehensive (loss)/income, net of tax			736,000	(550,000)	2,929,000	(251,000)
AOCI Attributable to Parent [Member]
Beginning balance, loss, net of tax		$ (2,511,000)	(20,906,000)	(3,642,000)	(2,511,000)	(3,715,000)
Net unrealized (losses)/gains arising during the period, pre-tax			(2,860,000)	3,837,000	(16,093,000)	3,497,000
Net unrealized (losses)/gains arising during the period, tax			(845,000)	1,613,000	(4,757,000)	1,470,000
Net unrealized (losses)/gains arising during the period, net of tax			(2,015,000)	2,224,000	(11,336,000)	2,027,000
Reclassification adjustment for net losses/(gains) included in net income, pre-tax				(3,000)		463,000
Reclassification adjustment for net losses/(gains) included in net income, tax				(1,000)		195,000
Reclassification adjustment for net losses/(gains) included in net income, net of tax				(2,000)		268,000
Total other comprehensive (loss)/income, pre-tax			(2,860,000)	3,834,000	(16,093,000)	3,960,000
Total other comprehensive (loss)/income, tax			(845,000)	1,612,000	(4,757,000)	1,665,000
Total other comprehensive (loss)/income, net of tax			(2,015,000)	2,222,000	(11,336,000)	2,295,000
Ending balance, loss, net of tax			(22,921,000)	(1,420,000)	(22,921,000)	(1,420,000)
Reclassification adjustment for stranded tax effects of Tax Cuts and Job Act, tax	[1]				515,000
Reclassification adjustment for stranded tax effects of Tax Cuts and Job Act, net of tax	[1]				(515,000)
Reclassification adjustment for equity securities, pre-tax	[2]				(12,151,000)
Reclassification adjustment for equity securities, tax	[2]				(3,592,000)
Reclassification adjustment for equity securities, net of tax	[2]				(8,559,000)
Total other comprehensive (loss)/income, pre-tax			(2,860,000)	3,834,000	(16,093,000)	3,960,000
Total other comprehensive (loss)/income, tax			(845,000)	1,612,000	(4,757,000)	1,665,000
Total other comprehensive (loss)/income, net of tax			$ (2,015,000)	$ 2,222,000	$ (11,336,000)	$ 2,295,000

[1] These amounts were recorded as of January 1, 2018 as a result of the adoption of ASU 2018-2.

[2] This amount was recorded as of January 1, 2018 as a result of the adoption of ASU 2016-1.