Note 3 - Loans Leases Receivable - Loans by Internally Assigned Risk Rating (Details) - USD ($)	Mar. 31, 2017	Dec. 31, 2016
Loans	$ 2,427,885,239	$ 2,397,414,282
Commercial Portfolio Segment [Member]
Loans	851,578,347	827,637,263
Commercial Portfolio Segment [Member] | Pass [Member]
Loans	816,089,950	796,568,451
Commercial Portfolio Segment [Member] | Special Mention [Member]
Loans	7,820,608	6,305,772
Commercial Portfolio Segment [Member] | Substandard [Member]
Loans	27,667,789	24,763,040
Commercial Portfolio Segment [Member] | Doubtful [Member]
Loans
Commercial Real Estate Portfolio Segment [Member]
Loans	1,106,841,721	1,093,458,860
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans	316,902,218	332,387,621
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans	171,901,708	165,149,491
Commercial Real Estate Portfolio Segment [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans	618,037,795	595,921,748
Commercial Real Estate Portfolio Segment [Member] | Pass [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans	298,438,590	314,447,662
Commercial Real Estate Portfolio Segment [Member] | Pass [Member] | Construction Loans [Member]
Loans	164,958,396	158,108,465
Commercial Real Estate Portfolio Segment [Member] | Pass [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans	605,282,623	582,854,048
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans	8,839,425	7,559,380
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member] | Construction Loans [Member]
Loans	1,780,000	1,780,000
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans	4,400,764	4,437,122
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans	9,624,203	10,380,369
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member] | Construction Loans [Member]
Loans	5,163,312	5,261,026
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans	8,354,408	8,630,578
Commercial Real Estate Portfolio Segment [Member] | Doubtful [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans		210
Commercial Real Estate Portfolio Segment [Member] | Doubtful [Member] | Construction Loans [Member]
Loans
Commercial Real Estate Portfolio Segment [Member] | Doubtful [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans
Commercial and Commercial Real Estate Portfolio Segments [Member]
Loans	$ 1,958,420,068	$ 1,921,096,123
As a % of Total	100.00%	100.00%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Pass [Member]
Loans	$ 1,884,769,559	$ 1,851,978,626
As a % of Total	96.24%	96.40%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Special Mention [Member]
Loans	$ 22,840,797	$ 20,082,274
As a % of Total	1.17%	1.05%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Substandard [Member]
Loans	$ 50,809,712	$ 49,035,013
As a % of Total	2.59%	2.55%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Doubtful [Member]
Loans		$ 210
As a % of Total	0.00%	0.00%