Note 3 - Loans Leases Receivable - Loans by Internally Assigned Risk Rating (Details) - USD ($)		Mar. 31, 2018	Dec. 31, 2017
Loans		$ 3,046,799,276	$ 2,956,713,493
Commercial Portfolio Segment [Member]
Loans	[1]	1,201,085,625	1,134,516,315
Commercial Portfolio Segment [Member] | Pass [Member]
Loans		1,079,132,775	1,031,963,703
Commercial Portfolio Segment [Member] | Special Mention [Member]
Loans		20,327,365	10,944,924
Commercial Portfolio Segment [Member] | Substandard [Member]
Loans		22,713,694	24,578,731
Commercial Portfolio Segment [Member] | Doubtful [Member]
Loans			270,559
Commercial Real Estate Portfolio Segment [Member]
Loans		1,357,703,386	1,303,491,882
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans		346,996,627	332,742,477
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans		171,404,628	186,402,404
Commercial Real Estate Portfolio Segment [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans		839,302,131	784,347,000
Commercial Real Estate Portfolio Segment [Member] | Pass [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans		337,628,357	318,293,608
Commercial Real Estate Portfolio Segment [Member] | Pass [Member] | Construction Loans [Member]
Loans		166,752,090	179,142,839
Commercial Real Estate Portfolio Segment [Member] | Pass [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans		813,622,461	767,119,909
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans		5,576,201	8,230,060
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		15,242,642	10,068,870
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans		3,792,069	6,218,809
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member] | Construction Loans [Member]
Loans		2,872,538	5,479,565
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans		10,437,028	7,158,221
Commercial Real Estate Portfolio Segment [Member] | Doubtful [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans
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		$ 2,479,877,220	$ 2,371,249,799
As a % of Total		100.00%	100.00%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Pass [Member]
Loans		$ 2,397,135,683	$ 2,296,520,059
As a % of Total		96.66%	96.85%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Special Mention [Member]
Loans		$ 42,926,208	$ 31,023,854
As a % of Total		1.73%	1.31%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Substandard [Member]
Loans		$ 39,815,329	$ 43,435,326
As a % of Total		1.61%	1.83%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Doubtful [Member]
Loans			$ 270,559
As a % of Total			0.01%

[1] Includes equipment financing agreements outstanding at m2, totaling $78,911,791 and $66,758,397 as of March 31, 2018 and December 31, 2017, respectively.