Note 4 - Loans Leases Receivable - Loans by Internally Assigned Risk Rating (Details) - USD ($)		Dec. 31, 2017	Dec. 31, 2016
Loans		$ 2,956,713,493	$ 2,397,414,282
Commercial Portfolio Segment [Member]
Loans	[1]	1,134,516,315	827,637,263
Commercial Portfolio Segment [Member] | Pass [Member]
Loans		1,098,722,101	796,568,451
Commercial Portfolio Segment [Member] | Special Mention [Member]
Loans		10,944,924	6,305,772
Commercial Portfolio Segment [Member] | Substandard [Member]
Loans		24,578,731	24,763,040
Commercial Portfolio Segment [Member] | Doubtful [Member]
Loans		270,559
Commercial Real Estate Portfolio Segment [Member]
Loans		1,303,491,882	1,093,458,860
Commercial Real Estate Portfolio Segment [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans		332,742,477	332,387,621
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Loans		186,402,404	165,149,491
Commercial Real Estate Portfolio Segment [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans		784,347,000	595,921,748
Commercial Real Estate Portfolio Segment [Member] | Pass [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans		318,293,608	314,447,662
Commercial Real Estate Portfolio Segment [Member] | Pass [Member] | Construction Loans [Member]
Loans		179,142,839	158,108,465
Commercial Real Estate Portfolio Segment [Member] | Pass [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans		767,119,909	582,854,048
Commercial Real Estate Portfolio Segment [Member] | Special Mention [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans		8,230,060	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		10,068,870	4,437,122
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member] | Owner Occupied Commercial Real Estate Loans [Member]
Loans		6,218,809	10,380,369
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member] | Construction Loans [Member]
Loans		5,479,565	5,261,026
Commercial Real Estate Portfolio Segment [Member] | Substandard [Member] | Other Non-owner Occupied Commercial Real Estate Loans [Member]
Loans		7,158,221	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		$ 2,438,008,197	$ 1,921,096,123
As a % of Total		100.00%	100.00%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Pass [Member]
Loans		$ 2,363,278,457	$ 1,851,978,626
As a % of Total		96.94%	96.40%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Special Mention [Member]
Loans		$ 31,023,854	$ 20,082,274
As a % of Total		1.27%	1.05%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Substandard [Member]
Loans		$ 43,435,326	$ 49,035,013
As a % of Total		1.78%	2.55%
Commercial and Commercial Real Estate Portfolio Segments [Member] | Doubtful [Member]
Loans		$ 270,559	$ 210
As a % of Total		0.01%	0.00%

[1] Includes loans outstanding at QCBT's wholly-owned subsidiary, m2, totaling $60,981,381 and $38,668,209 as of September 30, 2017 and December 31, 2016, respectively.