Note 4 - Credit Quality - Average Annual Recorded Investment and Interest Income Recognized on Impaired Loans Excluding Purchased Credit Impaired Loans (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Impaired loans with no related allowance, average recorded investment	$ 154	$ 151
Impaired loans with no related allowance, interest income recognized	21,408	26,974
Impaired loans with a related allowance, average recorded investment	68	133
Impaired loans with a related allowance, interest income rexognized	9,027	11,023
Total impaired loans, average recorded investment	222	284
Total impaired loans, interest income recognized	30,435	37,997
Commercial Portfolio Segment [Member] \| Construction, Development and Other Land [Member]
Impaired loans with no related allowance, average recorded investment
Impaired loans with no related allowance, interest income recognized	11	169
Impaired loans with a related allowance, average recorded investment
Impaired loans with a related allowance, interest income rexognized	428
Commercial Portfolio Segment [Member] \| Commercial and Industrial [Member]
Impaired loans with no related allowance, average recorded investment	2
Impaired loans with no related allowance, interest income recognized	330	147
Impaired loans with a related allowance, average recorded investment	15
Impaired loans with a related allowance, interest income rexognized	312
Commercial Portfolio Segment [Member] \| Multi-family Residential [Member]
Impaired loans with no related allowance, average recorded investment
Impaired loans with no related allowance, interest income recognized	356	68
Commercial Portfolio Segment [Member] \| Single Family Non-owner Occupied [Member]
Impaired loans with no related allowance, average recorded investment	43	16
Impaired loans with no related allowance, interest income recognized	3,326	2,018
Impaired loans with a related allowance, average recorded investment	8	7
Impaired loans with a related allowance, interest income rexognized	343	358
Commercial Portfolio Segment [Member] \| Non-farm, Non-residential [Member]
Impaired loans with no related allowance, average recorded investment	4	71
Impaired loans with no related allowance, interest income recognized	2,725	11,735
Impaired loans with a related allowance, average recorded investment	10	88
Impaired loans with a related allowance, interest income rexognized	1,154	5,358
Commercial Portfolio Segment [Member] \| Agricultural [Member]
Impaired loans with no related allowance, average recorded investment
Impaired loans with no related allowance, interest income recognized	126
Commercial Portfolio Segment [Member] \| Farmland [Member]
Impaired loans with no related allowance, average recorded investment
Impaired loans with no related allowance, interest income recognized	1,006	145
Consumer Real Estate Portfolio Segment [Member] \| Home Equity Lines [Member]
Impaired loans with no related allowance, average recorded investment	15	7
Impaired loans with no related allowance, interest income recognized	1,042	1,346
Impaired loans with a related allowance, average recorded investment
Impaired loans with a related allowance, interest income rexognized	417
Consumer Real Estate Portfolio Segment [Member] \| Single Family Owner Occupied [Member]
Impaired loans with no related allowance, average recorded investment	87	54
Impaired loans with no related allowance, interest income recognized	12,203	11,070
Impaired loans with a related allowance, average recorded investment	35	38
Impaired loans with a related allowance, interest income rexognized	6,373	4,961
Consumer Real Estate Portfolio Segment [Member] \| Owner Occupied Construction [Member]
Impaired loans with no related allowance, average recorded investment	3	3
Impaired loans with no related allowance, interest income recognized	233	241
Impaired loans with a related allowance, average recorded investment
Impaired loans with a related allowance, interest income rexognized		346
Consumer and Other Portfolio Segment [Member] \| Consumer Loan [Member]
Impaired loans with no related allowance, average recorded investment
Impaired loans with no related allowance, interest income recognized	$ 50	$ 35

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

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