Note 8 - Regulatory Capital Requirements (Details) - Capital Requirements - USD ($) $ in Thousands		Mar. 31, 2016		Dec. 31, 2015
Parent Company [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total risk-based capital, actual, amount				$ 280,273
Total risk-based capital, actual, ratio		12.68%		13.11%
Total risk-based capital for capital adequacy purposes, amount		$ 192,416	[1]	$ 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		$ 223,091		$ 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				$ 253,891
Tier 1 risk-based capital, actual, ratio		11.45%		11.88%
Tier 1 risk-based capital for capital adequacy purposes, amount		$ 147,797	[1]	$ 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		$ 178,472		$ 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				$ 253,891
Tier 1 leverage, actual, ratio		9.85%		9.75%
Tier 1 leverage for capital adequacy purposes, amount		$ 103,728	[1]	$ 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		$ 129,660		$ 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				$ 220,800
Common equity Tier 1, actual ratio		10.11%		10.33%
Common equity Tier 1 capital adequacy purposes, amount		$ 114,334	[1]	$ 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		$ 145,009		$ 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]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total risk-based capital, actual, amount				$ 135,477
Total risk-based capital, actual, ratio		12.01%		12.50%
Total risk-based capital for capital adequacy purposes, amount		$ 98,496	[1]	$ 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		$ 114,198		$ 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				$ 123,498
Tier 1 risk-based capital, actual, ratio		10.92%		11.39%
Tier 1 risk-based capital for capital adequacy purposes, amount		$ 75,656	[1]	$ 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		$ 91,358		$ 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				$ 123,498
Tier 1 leverage, actual, ratio		9.12%		8.87%
Tier 1 leverage for capital adequacy purposes, amount		$ 54,680	[1]	$ 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		$ 68,351		$ 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				$ 123,498
Common equity Tier 1, actual ratio		10.92%		11.39%
Common equity Tier 1 capital adequacy purposes, amount		$ 58,526	[1]	$ 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		$ 74,229		$ 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]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total risk-based capital, actual, amount				$ 105,285
Total risk-based capital, actual, ratio		13.98%		14.39%
Total risk-based capital for capital adequacy purposes, amount		$ 65,729	[1]	$ 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		$ 76,208		$ 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				$ 96,118
Tier 1 risk-based capital, actual, ratio		12.73%		13.14%
Tier 1 risk-based capital for capital adequacy purposes, amount		$ 50,488	[1]	$ 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		$ 60,966		$ 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				$ 96,118
Tier 1 leverage, actual, ratio		11.03%		10.96%
Tier 1 leverage for capital adequacy purposes, amount		$ 35,197	[1]	$ 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		$ 43,996		$ 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				$ 96,118
Common equity Tier 1, actual ratio		12.73%		13.14%
Common equity Tier 1 capital adequacy purposes, amount		$ 39,056	[1]	$ 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		$ 49,535		$ 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]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total risk-based capital, actual, amount				$ 38,544
Total risk-based capital, actual, ratio		12.03%		11.96%
Total risk-based capital for capital adequacy purposes, amount		$ 28,096	[1]	$ 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		$ 32,575		$ 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				$ 34,514
Tier 1 risk-based capital, actual, ratio		10.78%		10.71%
Tier 1 risk-based capital for capital adequacy purposes, amount		$ 21,581	[1]	$ 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		$ 26,060		$ 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				$ 34,514
Tier 1 leverage, actual, ratio		9.52%		9.59%
Tier 1 leverage for capital adequacy purposes, amount		$ 14,758	[1]	$ 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		$ 18,447		$ 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				$ 34,514
Common equity Tier 1, actual ratio		10.78%		10.71%
Common equity Tier 1 capital adequacy purposes, amount		$ 16,695	[1]	$ 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		$ 21,174		$ 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.