Note 4 - Loans Leases Receivable - Loans by Internally Assigned Risk Rating (Details) - USD ($)	Sep. 30, 2018	Dec. 31, 2017
Loans and leases	$ 3,644,099,503	$ 2,956,713,493
Commercial Portfolio Segment [Member]
Loans and leases	1,380,542,524	1,134,516,315
Commercial Portfolio Segment [Member] | Internally Assigned Risk Rating [Member]
Loans and leases	1,281,719,173	1,067,757,917
Commercial Portfolio Segment [Member] | Pass [Member]
Loans and leases	1,236,971,045	1,031,963,703
Commercial Portfolio Segment [Member] | Special Mention [Member]
Loans and leases	28,051,461	10,944,924
Commercial Portfolio Segment [Member] | Substandard [Member]
Loans and leases	16,693,746	24,578,731
Commercial Portfolio Segment [Member] | Doubtful [Member]
Loans and leases	2,921	270,559
Commercial Real Estate Portfolio Segment [Member]
Loans and leases	1,727,326,190	1,303,491,882
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	449,056,125	332,742,477
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans and leases	224,295,259	186,402,404
Commercial Real Estate Portfolio Segment [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	1,053,974,806	784,347,000
Commercial Real Estate Portfolio Segment [Member] | Internally Assigned Risk Rating [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	449,056,125	332,742,477
Commercial Real Estate Portfolio Segment [Member] | Internally Assigned Risk Rating [Member] | Construction Loans [Member]
Loans and leases	224,295,259	186,402,404
Commercial Real Estate Portfolio Segment [Member] | Internally Assigned Risk Rating [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	1,053,974,806	784,347,000
Commercial Real Estate Portfolio Segment [Member] | Pass [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	438,799,404	318,293,608
Commercial Real Estate Portfolio Segment [Member] | Pass [Member] | Construction Loans [Member]
Loans and leases	216,655,705	179,142,839
Commercial Real Estate Portfolio Segment [Member] | Pass [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	1,021,710,298	767,119,909
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	6,972,157	8,230,060
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member] | Construction Loans [Member]
Loans and leases	3,850,042	1,780,000
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	10,356,053	10,068,870
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	3,284,564	6,218,809
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member] | Construction Loans [Member]
Loans and leases	3,789,512	5,479,565
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	21,908,455	7,158,221
Commercial and Commercial Real Estate Portfolio Segments [Member] | Internally Assigned Risk Rating [Member]
Loans and leases	$ 3,009,045,363	$ 2,371,249,799
As a % of Total	100.00%	100.00%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Pass [Member]
Loans and leases	$ 2,914,136,452	$ 2,296,520,059
As a % of Total	96.85%	96.85%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Special Mention [Member]
Loans and leases	$ 49,229,713	$ 31,023,854
As a % of Total	1.64%	1.31%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Substandard [Member]
Loans and leases	$ 45,676,277	$ 43,435,326
As a % of Total	1.51%	1.83%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Doubtful [Member]
Loans and leases	$ 2,921	$ 270,559
As a % of Total		0.01%