Note 6 - Debt and Equity Securities (Details) - Available for Sale Securities With Gross Unrealized Losses and Their Fair Value - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Note 6 - Debt and Equity Securities (Details) - Available for Sale Securities With Gross Unrealized Losses and Their Fair Value [Line Items]
Fair Value	$ 500,808	$ 374,858
Unrealized Losses	9,912	7,259
Less Than 12 Months - Fair Value	408,587	97,274
Less Than 12 Months - Unrealized Losses	7,032	846
12 Months or More - Fair Value	92,221	277,584
12 Months or More - Unrealized Losses	2,880	6,413
Corporate Debt Securities [Member]
Note 6 - Debt and Equity Securities (Details) - Available for Sale Securities With Gross Unrealized Losses and Their Fair Value [Line Items]
Fair Value	85,563	39,287
Unrealized Losses	4,436	714
Less Than 12 Months - Fair Value	76,218	9,573
Less Than 12 Months - Unrealized Losses	3,782	428
12 Months or More - Fair Value	9,345	29,714
12 Months or More - Unrealized Losses	654	286
Collateralized Debt Obligations [Member]
Note 6 - Debt and Equity Securities (Details) - Available for Sale Securities With Gross Unrealized Losses and Their Fair Value [Line Items]
Fair Value	52,898
Unrealized Losses	327
Less Than 12 Months - Fair Value	52,898
Less Than 12 Months - Unrealized Losses	327
Other Debt Obligations [Member]
Note 6 - Debt and Equity Securities (Details) - Available for Sale Securities With Gross Unrealized Losses and Their Fair Value [Line Items]
Fair Value	298	292
Unrealized Losses	2	8
12 Months or More - Fair Value	298	292
12 Months or More - Unrealized Losses	2	8
Available For Sale Securities, Excluding Mortgage-Backed Securities [Member]
Note 6 - Debt and Equity Securities (Details) - Available for Sale Securities With Gross Unrealized Losses and Their Fair Value [Line Items]
Fair Value	138,759	48,389
Unrealized Losses	4,765	783
Less Than 12 Months - Fair Value	129,116	13,119
Less Than 12 Months - Unrealized Losses	4,109	439
12 Months or More - Fair Value	9,643	35,270
12 Months or More - Unrealized Losses	656	344
REMIC and CMO [Member]
Note 6 - Debt and Equity Securities (Details) - Available for Sale Securities With Gross Unrealized Losses and Their Fair Value [Line Items]
Fair Value	238,132	216,190
Unrealized Losses	3,147	4,627
Less Than 12 Months - Fair Value	182,010	77,382
Less Than 12 Months - Unrealized Losses	1,642	399
12 Months or More - Fair Value	56,122	138,808
12 Months or More - Unrealized Losses	1,505	4,228
GNMA [Member]
Note 6 - Debt and Equity Securities (Details) - Available for Sale Securities With Gross Unrealized Losses and Their Fair Value [Line Items]
Fair Value	6,977	8,358
Unrealized Losses	139	124
Less Than 12 Months - Fair Value	6,977
Less Than 12 Months - Unrealized Losses	139
12 Months or More - Fair Value		8,358
12 Months or More - Unrealized Losses		124
FNMA [Member]
Note 6 - Debt and Equity Securities (Details) - Available for Sale Securities With Gross Unrealized Losses and Their Fair Value [Line Items]
Fair Value	102,225	95,148
Unrealized Losses	1,762	1,717
Less Than 12 Months - Fair Value	75,769
Less Than 12 Months - Unrealized Losses	1,043
12 Months or More - Fair Value	26,456	95,148
12 Months or More - Unrealized Losses	719	1,717
FHLMC [Member]
Note 6 - Debt and Equity Securities (Details) - Available for Sale Securities With Gross Unrealized Losses and Their Fair Value [Line Items]
Fair Value	14,715	6,773
Unrealized Losses	99	8
Less Than 12 Months - Fair Value	14,715	6,773
Less Than 12 Months - Unrealized Losses	99	8
Collateralized Mortgage Backed Securities [Member]
Note 6 - Debt and Equity Securities (Details) - Available for Sale Securities With Gross Unrealized Losses and Their Fair Value [Line Items]
Fair Value	362,049	326,469
Unrealized Losses	5,147	6,476
Less Than 12 Months - Fair Value	279,471	84,155
Less Than 12 Months - Unrealized Losses	2,923	407
12 Months or More - Fair Value	82,578	242,314
12 Months or More - Unrealized Losses	$ 2,224	6,069
Municipal [Member]
Note 6 - Debt and Equity Securities (Details) - Available for Sale Securities With Gross Unrealized Losses and Their Fair Value [Line Items]
Fair Value		8,810
Unrealized Losses		61
Less Than 12 Months - Fair Value		3,546
Less Than 12 Months - Unrealized Losses		11
12 Months or More - Fair Value		5,264
12 Months or More - Unrealized Losses		$ 50

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