Note 4 - Debt and Equity Securities - Amortized Cost and Fair Value of Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Securities held-to-maturity, amortized cost	$ 30,930	$ 37,735
Securities held-to-maturity, fair value	29,381	35,408
Securities held-to-maturity, gross unrealized gains	0	0
Securities held-to-maturity, gross unrealized losses	1,549	2,327
Securities available for sale, amortized cost	800,577	868,009
Securities available for sale, fair value	796,559	861,381
Securities available for sale, gross unrealized gains	5,847	5,091
Securities available for sale, gross unrealized losses	9,865	11,719
Municipal Debt Securities [Member]
Securities held-to-maturity, amortized cost	22,952	37,735
Securities held-to-maturity, fair value	21,542	35,408
Securities held-to-maturity, gross unrealized gains	0	0
Securities held-to-maturity, gross unrealized losses	1,410	2,327
Securities available for sale, amortized cost	102,226	124,984
Securities available for sale, fair value	104,979	126,903
Securities available for sale, gross unrealized gains	2,753	1,983
Securities available for sale, gross unrealized losses	0	64
Corporate Debt Securities [Member]
Securities available for sale, amortized cost	110,000	110,000
Securities available for sale, fair value	103,126	102,910
Securities available for sale, gross unrealized gains	0
Securities available for sale, gross unrealized losses	6,874	7,090
Other Debt Obligations [Member]
Securities held-to-maturity, amortized cost	22,952	37,735
Securities held-to-maturity, fair value	21,542	35,408
Securities held-to-maturity, gross unrealized gains
Securities held-to-maturity, gross unrealized losses	1,410
Securities available for sale, fair value	276,698	344,905
FNMA [Member]
Securities held-to-maturity, amortized cost	7,978
Securities held-to-maturity, fair value	7,839
Securities held-to-maturity, gross unrealized gains
Securities held-to-maturity, gross unrealized losses	139
Securities available for sale, amortized cost	138,995	109,493
Securities available for sale, fair value	138,781	108,351
Securities available for sale, gross unrealized gains	547	463
Securities available for sale, gross unrealized losses	761	1,605
Mutual Fund Debt Securities [Member]
Securities available for sale, amortized cost	18,629	21,366
Securities available for sale, fair value	18,629	21,366
Securities available for sale, gross unrealized gains	0	0
Securities available for sale, gross unrealized losses	0	0
Collateralized Mortgage Backed Securities [Member]
Securities held-to-maturity, amortized cost	7,978
Securities held-to-maturity, fair value	7,839
Securities held-to-maturity, gross unrealized gains
Securities held-to-maturity, gross unrealized losses	139
Securities available for sale, amortized cost	520,241	518,826
Securities available for sale, fair value	519,861	516,476
Securities available for sale, gross unrealized gains	2,611	2,213
Securities available for sale, gross unrealized losses	2,991	4,563
Collateralized Debt Obligations [Member]
Securities available for sale, amortized cost	48,398	85,470
Securities available for sale, fair value	48,881	86,365
Securities available for sale, gross unrealized gains	483	895
Securities available for sale, gross unrealized losses	0
Other Securities [Member]
Securities available for sale, amortized cost	1,083	7,363
Securities available for sale, fair value	1,083	7,361
Securities available for sale, gross unrealized gains	0	0
Securities available for sale, gross unrealized losses		2
Available for Sale Securities Excluding Mortgage Backed Securities [Member]
Securities available for sale, amortized cost	280,336	349,183
Securities available for sale, fair value	276,698	344,905
Securities available for sale, gross unrealized gains	3,236	2,878
Securities available for sale, gross unrealized losses	6,874	7,156
REMIC and CMO [Member]
Securities available for sale, amortized cost	330,593	402,636
Securities available for sale, fair value	330,459	401,370
Securities available for sale, gross unrealized gains	1,953	1,607
Securities available for sale, gross unrealized losses	2,087	2,873
GNMA [Member]
Securities available for sale, amortized cost	1,096	1,319
Securities available for sale, fair value	1,184	1,427
Securities available for sale, gross unrealized gains	88	108
Securities available for sale, gross unrealized losses	0
FHLMC [Member]
Securities available for sale, amortized cost	49,557	5,378
Securities available for sale, fair value	49,437	5,328
Securities available for sale, gross unrealized gains	23	35
Securities available for sale, gross unrealized losses	$ 143	$ 85

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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