Note 8 - Capital Requirements (Details) - USD ($)		Jun. 30, 2016	Dec. 31, 2015
Parent Company [Member]
Total risk-based capital, actual, amount		$ 322,562	$ 280,273
Total risk-based capital, actual, ratio		14.29%	13.11%
Total risk-based capital for capital adequacy purposes, amount	[1]	$ 194,670	$ 170,969
Total risk-based capital for capital adequacy purposes, ratio	[1]	8.625%	8.00%
Total risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 225,705	$ 213,711
Total risk-based capital to be well capitalized under prompt corrective action provisions, ratio		10.00%	10.00%
Tier 1 risk-based capital, actual, amount		$ 294,265	$ 253,891
Tier 1 risk-based capital, actual, ratio		13.04%	11.88%
Tier 1 risk-based capital for capital adequacy purposes, amount	[1]	$ 149,529	$ 128,227
Tier 1 risk-based capital for capital adequacy purposes, ratio	[1]	6.625%	6.00%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 180,564	$ 170,969
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, ratio		8.00%	8.00%
Tier 1 leverage, actual, amount		$ 294,265	$ 253,891
Tier 1 leverage, actual, ratio		11.18%	9.75%
Tier 1 leverage for capital adequacy purposes, amount	[1]	$ 105,263	$ 104,163
Tier 1 leverage for capital adequacy purposes, ratio	[1]	4.00%	4.00%
Tier 1 leverage to be well capitalized under prompt corrective action provisions, amount		$ 131,578	$ 130,203
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 264,422	$ 220,800
Common equity Tier 1, actual ratio		11.72%	10.33%
Common equity Tier 1 capital adequacy purposes, amount	[1]	$ 115,674	$ 96,170
Common equity Tier 1 capital adequacy purposes, ratio	[1]	5.125%	4.50%
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, amount		$ 146,708	$ 138,912
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, ratio		6.50%	6.50%
Quad City Bank and Trust Company [Member]
Total risk-based capital, actual, amount		$ 143,744	$ 135,477
Total risk-based capital, actual, ratio		12.76%	12.50%
Total risk-based capital for capital adequacy purposes, amount	[1]	$ 97,131	$ 86,726
Total risk-based capital for capital adequacy purposes, ratio	[1]	8.625%	8.00%
Total risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 112,616	$ 108,407
Total risk-based capital to be well capitalized under prompt corrective action provisions, ratio		10.00%	10.00%
Tier 1 risk-based capital, actual, amount		$ 131,003	$ 123,498
Tier 1 risk-based capital, actual, ratio		11.63%	11.39%
Tier 1 risk-based capital for capital adequacy purposes, amount	[1]	$ 74,608	$ 65,044
Tier 1 risk-based capital for capital adequacy purposes, ratio	[1]	6.625%	6.00%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 90,093	$ 86,726
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, ratio		8.00%	8.00%
Tier 1 leverage, actual, amount		$ 131,003	$ 123,498
Tier 1 leverage, actual, ratio		9.42%	8.87%
Tier 1 leverage for capital adequacy purposes, amount	[1]	$ 55,618	$ 55,718
Tier 1 leverage for capital adequacy purposes, ratio	[1]	4.00%	4.00%
Tier 1 leverage to be well capitalized under prompt corrective action provisions, amount		$ 69,523	$ 69,648
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 131,003	$ 123,498
Common equity Tier 1, actual ratio		11.63%	11.39%
Common equity Tier 1 capital adequacy purposes, amount	[1]	$ 57,716	$ 48,783
Common equity Tier 1 capital adequacy purposes, ratio	[1]	5.125%	4.50%
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, amount		$ 73,200	$ 70,465
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, ratio		6.50%	6.50%
Cedar Rapids Bank and Trust [Member]
Total risk-based capital, actual, amount		$ 110,325	$ 105,285
Total risk-based capital, actual, ratio		13.82%	14.39%
Total risk-based capital for capital adequacy purposes, amount	[1]	$ 68,850	$ 58,537
Total risk-based capital for capital adequacy purposes, ratio	[1]	8.625%	8.00%
Total risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 79,826	$ 73,172
Total risk-based capital to be well capitalized under prompt corrective action provisions, ratio		10.00%	10.00%
Tier 1 risk-based capital, actual, amount		$ 100,331	$ 96,118
Tier 1 risk-based capital, actual, ratio		12.57%	13.14%
Tier 1 risk-based capital for capital adequacy purposes, amount	[1]	$ 52,885	$ 43,903
Tier 1 risk-based capital for capital adequacy purposes, ratio	[1]	6.625%	6.00%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 63,861	$ 58,537
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, ratio		8.00%	8.00%
Tier 1 leverage, actual, amount		$ 100,331	$ 96,118
Tier 1 leverage, actual, ratio		11.20%	10.96%
Tier 1 leverage for capital adequacy purposes, amount	[1]	$ 35,830	$ 35,079
Tier 1 leverage for capital adequacy purposes, ratio	[1]	4.00%	4.00%
Tier 1 leverage to be well capitalized under prompt corrective action provisions, amount		$ 44,788	$ 43,848
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 100,331	$ 96,118
Common equity Tier 1, actual ratio		12.57%	13.14%
Common equity Tier 1 capital adequacy purposes, amount	[1]	$ 40,911	$ 32,927
Common equity Tier 1 capital adequacy purposes, ratio	[1]	5.125%	4.50%
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, amount		$ 51,887	$ 47,562
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, ratio		6.50%	6.50%
Rockford Bank and Trust [Member]
Total risk-based capital, actual, amount		$ 40,108	$ 38,544
Total risk-based capital, actual, ratio		11.87%	11.96%
Total risk-based capital for capital adequacy purposes, amount	[1]	$ 29,154	$ 25,772
Total risk-based capital for capital adequacy purposes, ratio	[1]	8.625%	8.00%
Total risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 33,801	$ 32,216
Total risk-based capital to be well capitalized under prompt corrective action provisions, ratio		10.00%	10.00%
Tier 1 risk-based capital, actual, amount		$ 35,877	$ 34,514
Tier 1 risk-based capital, actual, ratio		10.61%	10.71%
Tier 1 risk-based capital for capital adequacy purposes, amount	[1]	$ 22,393	$ 19,329
Tier 1 risk-based capital for capital adequacy purposes, ratio	[1]	6.625%	6.00%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 27,041	$ 25,772
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, ratio		8.00%	8.00%
Tier 1 leverage, actual, amount		$ 35,877	$ 34,514
Tier 1 leverage, actual, ratio		9.50%	9.59%
Tier 1 leverage for capital adequacy purposes, amount	[1]	$ 15,099	$ 14,401
Tier 1 leverage for capital adequacy purposes, ratio	[1]	4.00%	4.00%
Tier 1 leverage to be well capitalized under prompt corrective action provisions, amount		$ 18,874	$ 18,001
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 35,877	$ 34,514
Common equity Tier 1, actual ratio		10.61%	10.71%
Common equity Tier 1 capital adequacy purposes, amount	[1]	$ 17,323	$ 14,497
Common equity Tier 1 capital adequacy purposes, ratio	[1]	5.125%	4.50%
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, amount		$ 21,971	$ 20,940
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, ratio		6.50%	6.50%

[1] The minimums under Basel III phase in higher by .625% (the capital conservation buffer) annually until 2019. The fully phased-in minimums are 10.5% (Total risk-based capital), 8.5% (Tier 1 risk-based capital), and 7.0% (Common equity Tier 1). At December 31, 2015, the New Basel III minimums mirrored the minimums required for capital adequacy purposes. The first phase-in of the Basel III capital conservation buffer occured in 2016.