Note 3 - Loans Leases Receivable - Loans by Internally Assigned Risk Rating (Details) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Loans and leases	$ 3,105,901,458	$ 2,956,713,493
Commercial Portfolio Segment [Member]
Loans and leases	1,273,000,094	1,134,516,315
Commercial Portfolio Segment [Member] | Internally Assigned Risk Rating [Member]
Loans and leases	1,180,184,352	1,067,757,917
Commercial Portfolio Segment [Member] | Pass [Member]
Loans and leases	1,135,035,263	1,031,963,703
Commercial Portfolio Segment [Member] | Special Mention [Member]
Loans and leases	29,414,324	10,944,924
Commercial Portfolio Segment [Member] | Substandard [Member]
Loans and leases	15,734,765	24,578,731
Commercial Portfolio Segment [Member] | Doubtful [Member]
Loans and leases		270,559
Commercial Real Estate Portfolio Segment [Member]
Loans and leases	1,349,318,914	1,303,491,882
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	349,007,830	332,742,477
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans and leases	162,644,566	186,402,404
Commercial Real Estate Portfolio Segment [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	837,666,518	784,347,000
Commercial Real Estate Portfolio Segment [Member] | Internally Assigned Risk Rating [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	349,007,830	332,742,477
Commercial Real Estate Portfolio Segment [Member] | Internally Assigned Risk Rating [Member] | Construction Loans [Member]
Loans and leases	162,644,566	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	837,666,518	784,347,000
Commercial Real Estate Portfolio Segment [Member] | Pass [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	342,518,625	318,293,608
Commercial Real Estate Portfolio Segment [Member] | Pass [Member] | Construction Loans [Member]
Loans and leases	160,224,065	179,142,839
Commercial Real Estate Portfolio Segment [Member] | Pass [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	805,031,050	767,119,909
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	3,984,113	8,230,060
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member] | Construction Loans [Member]
Loans and leases		1,780,000
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	10,804,187	10,068,870
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	2,505,092	6,218,809
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member] | Construction Loans [Member]
Loans and leases	2,420,501	5,479,565
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans and leases	21,831,281	7,158,221
Commercial and Commercial Real Estate Portfolio Segments [Member] | Internally Assigned Risk Rating [Member]
Loans and leases	$ 2,529,503,266	$ 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	$ 2,442,809,003	$ 2,296,520,059
As a % of Total	96.57%	96.85%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Special Mention [Member]
Loans and leases	$ 44,202,624	$ 31,023,854
As a % of Total	1.75%	1.31%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Substandard [Member]
Loans and leases	$ 42,491,639	$ 43,435,326
As a % of Total	1.68%	1.83%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Doubtful [Member]
Loans and leases		$ 270,559
As a % of Total		0.01%