Note 7 - Regulatory Capital Requirements and Restrictions on Dividends - Capital Requirements (Details) - USD ($)		Jun. 30, 2017	Dec. 31, 2016
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 281,774	$ 266,419
Common equity Tier 1, actual ratio		9.46%	9.41%
Common equity Tier 1 for capital adequacy purposes, amount, without capital conservation buffer	[1]	$ 134,101	$ 127,455
Common equity Tier 1 for capital adequacy purposes, ratio, without capital conservation buffer	[1]	4.50%	4.50%
Common equity Tier 1 for capital adequacy purposes, amount	[1]	$ 171,352	$ 145,157
Common equity Tier 1 for capital adequacy purposes, ratio	[1]	5.75%	5.125%
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, amount		$ 193,702	$ 184,102
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, ratio		6.50%	6.50%
Total risk-based capital, actual, amount		$ 347,033	$ 327,440
Total risk-based capital, actual, ratio		11.65%	11.56%
Total risk-based capital for capital adquacy purposes, amount, without capital conservation buffer	[1]	$ 238,402	$ 226,587
Total risk-based capital for capital adquacy purposes, ratio, without capital conservation buffer	[1]	8.00%	8.00%
Total risk-based capital for capital adquacy purposes, amount	[1]	$ 275,652	$ 244,289
Total risk-based capital for capital adquacy purposes, ratio	[1]	9.25%	8.625%
Total risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 298,003	$ 283,233
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		$ 313,333	$ 296,366
Tier 1 risk-based capital, actual, ratio		10.51%	10.46%
Tier 1 risk-based capital for capital adequacy purposes, amount, without capital conservation buffer	[1]	$ 178,802	$ 169,940
Tier 1 risk-based capital for capital adequacy purposes, ratio, without capital conservation buffer	[1]	6.00%	6.00%
Tier 1 risk-based capital for capital adequacy purposes, amount	[1]	$ 216,052	$ 187,642
Tier 1 risk-based capital for capital adequacy purposes, ratio	[1]	7.25%	6.625%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 238,402	$ 226,587
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, ratio		8.00%	8.00%
Tier 1 leverage, actual, amount		$ 313,333	$ 296,366
Tier 1 leverage, actual, ratio		9.34%	9.10%
Tier 1 leverage for capital adequacy purposes, amount, without capital conservation buffer	[1]	$ 134,142	$ 130,229
Tier 1 leverage for capital adequacy purposes, ratio, without capital conservation buffer	[1]	4.00%	4.00%
Tier 1 leverage for capital adequacy purposes, amount	[1]	$ 134,142	$ 130,229
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		$ 167,677	$ 162,787
Quad City Bank and Trust Company [Member]
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 135,628	$ 129,524
Common equity Tier 1, actual ratio		11.46%	11.12%
Common equity Tier 1 for capital adequacy purposes, amount, without capital conservation buffer	[1]	$ 53,278	$ 52,432
Common equity Tier 1 for capital adequacy purposes, ratio, without capital conservation buffer	[1]	4.50%	4.50%
Common equity Tier 1 for capital adequacy purposes, amount	[1]	$ 68,078	$ 59,714
Common equity Tier 1 for capital adequacy purposes, ratio	[1]	5.75%	5.125%
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, amount		$ 76,957	$ 75,735
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, ratio		6.50%	6.50%
Total risk-based capital, actual, amount		$ 149,008	$ 142,990
Total risk-based capital, actual, ratio		12.59%	12.27%
Total risk-based capital for capital adquacy purposes, amount, without capital conservation buffer	[1]	$ 94,717	$ 93,212
Total risk-based capital for capital adquacy purposes, ratio, without capital conservation buffer	[1]	8.00%	8.00%
Total risk-based capital for capital adquacy purposes, amount	[1]	$ 109,516	$ 100,494
Total risk-based capital for capital adquacy purposes, ratio	[1]	9.25%	8.625%
Total risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 118,396	$ 116,515
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		$ 135,628	$ 129,524
Tier 1 risk-based capital, actual, ratio		11.46%	11.12%
Tier 1 risk-based capital for capital adequacy purposes, amount, without capital conservation buffer	[1]	$ 71,038	$ 69,909
Tier 1 risk-based capital for capital adequacy purposes, ratio, without capital conservation buffer	[1]	6.00%	6.00%
Tier 1 risk-based capital for capital adequacy purposes, amount	[1]	$ 85,837	$ 77,191
Tier 1 risk-based capital for capital adequacy purposes, ratio	[1]	7.25%	6.625%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 94,717	$ 93,212
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, ratio		8.00%	8.00%
Tier 1 leverage, actual, amount		$ 135,628	$ 129,524
Tier 1 leverage, actual, ratio		9.56%	9.18%
Tier 1 leverage for capital adequacy purposes, amount, without capital conservation buffer	[1]	$ 56,719	$ 56,445
Tier 1 leverage for capital adequacy purposes, ratio, without capital conservation buffer	[1]	4.00%	4.00%
Tier 1 leverage for capital adequacy purposes, amount	[1]	$ 56,719	$ 56,445
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		$ 70,898	$ 70,556
Cedar Rapids Bank and Trust [Member]
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 99,216	$ 96,369
Common equity Tier 1, actual ratio		10.94%	11.57%
Common equity Tier 1 for capital adequacy purposes, amount, without capital conservation buffer	[1]	$ 40,825	$ 37,476
Common equity Tier 1 for capital adequacy purposes, ratio, without capital conservation buffer	[1]	4.50%	4.50%
Common equity Tier 1 for capital adequacy purposes, amount	[1]	$ 52,165	$ 42,681
Common equity Tier 1 for capital adequacy purposes, ratio	[1]	5.75%	5.125%
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, amount		$ 58,969	$ 54,132
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, ratio		6.50%	6.50%
Total risk-based capital, actual, amount		$ 110,561	$ 106,791
Total risk-based capital, actual, ratio		12.19%	12.82%
Total risk-based capital for capital adquacy purposes, amount, without capital conservation buffer	[1]	$ 72,578	$ 66,623
Total risk-based capital for capital adquacy purposes, ratio, without capital conservation buffer	[1]	8.00%	8.00%
Total risk-based capital for capital adquacy purposes, amount	[1]	$ 83,918	$ 71,828
Total risk-based capital for capital adquacy purposes, ratio	[1]	9.25%	8.625%
Total risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 90,722	$ 83,279
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		$ 99,216	$ 96,369
Tier 1 risk-based capital, actual, ratio		10.94%	11.57%
Tier 1 risk-based capital for capital adequacy purposes, amount, without capital conservation buffer	[1]	$ 54,434	$ 49,968
Tier 1 risk-based capital for capital adequacy purposes, ratio, without capital conservation buffer	[1]	6.00%	6.00%
Tier 1 risk-based capital for capital adequacy purposes, amount	[1]	$ 65,774	$ 55,173
Tier 1 risk-based capital for capital adequacy purposes, ratio	[1]	7.25%	6.625%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 72,578	$ 66,623
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, ratio		8.00%	8.00%
Tier 1 leverage, actual, amount		$ 99,216	$ 96,369
Tier 1 leverage, actual, ratio		10.43%	10.69%
Tier 1 leverage for capital adequacy purposes, amount, without capital conservation buffer	[1]	$ 38,044	$ 36,061
Tier 1 leverage for capital adequacy purposes, ratio, without capital conservation buffer	[1]	4.00%	4.00%
Tier 1 leverage for capital adequacy purposes, amount	[1]	$ 38,044	$ 36,061
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		$ 47,555	$ 45,076
Community State Bank [Member]
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 66,089	$ 66,746
Common equity Tier 1, actual ratio		12.72%	13.51%
Common equity Tier 1 for capital adequacy purposes, amount, without capital conservation buffer	[1]	$ 23,387	$ 22,231
Common equity Tier 1 for capital adequacy purposes, ratio, without capital conservation buffer	[1]	4.50%	4.50%
Common equity Tier 1 for capital adequacy purposes, amount	[1]	$ 29,884	$ 25,319
Common equity Tier 1 for capital adequacy purposes, ratio	[1]	5.75%	5.125%
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, amount		$ 33,782	$ 32,111
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, ratio		6.50%	6.50%
Total risk-based capital, actual, amount		$ 69,222	$ 68,216
Total risk-based capital, actual, ratio		13.32%	13.81%
Total risk-based capital for capital adquacy purposes, amount, without capital conservation buffer	[1]	$ 41,577	$ 39,521
Total risk-based capital for capital adquacy purposes, ratio, without capital conservation buffer	[1]	8.00%	8.00%
Total risk-based capital for capital adquacy purposes, amount	[1]	$ 48,074	$ 42,609
Total risk-based capital for capital adquacy purposes, ratio	[1]	9.25%	8.625%
Total risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 51,972	$ 49,402
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		$ 66,089	$ 66,746
Tier 1 risk-based capital, actual, ratio		12.72%	13.51%
Tier 1 risk-based capital for capital adequacy purposes, amount, without capital conservation buffer	[1]	$ 31,183	$ 29,641
Tier 1 risk-based capital for capital adequacy purposes, ratio, without capital conservation buffer	[1]	6.00%	6.00%
Tier 1 risk-based capital for capital adequacy purposes, amount	[1]	$ 37,679	$ 32,729
Tier 1 risk-based capital for capital adequacy purposes, ratio	[1]	7.25%	6.625%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 41,577	$ 39,522
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, ratio		8.00%	8.00%
Tier 1 leverage, actual, amount		$ 66,089	$ 66,746
Tier 1 leverage, actual, ratio		10.91%	11.75%
Tier 1 leverage for capital adequacy purposes, amount, without capital conservation buffer	[1]	$ 24,231	$ 22,726
Tier 1 leverage for capital adequacy purposes, ratio, without capital conservation buffer	[1]	4.00%	4.00%
Tier 1 leverage for capital adequacy purposes, amount	[1]	$ 24,231	$ 22,726
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		$ 30,289	$ 28,408
Rockford Bank and Trust [Member]
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 39,384	$ 37,716
Common equity Tier 1, actual ratio		10.53%	11.01%
Common equity Tier 1 for capital adequacy purposes, amount, without capital conservation buffer	[1]	$ 16,831	$ 15,418
Common equity Tier 1 for capital adequacy purposes, ratio, without capital conservation buffer	[1]	4.50%	4.50%
Common equity Tier 1 for capital adequacy purposes, amount	[1]	$ 21,507	$ 17,559
Common equity Tier 1 for capital adequacy purposes, ratio	[1]	5.75%	5.125%
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, amount		$ 24,312	$ 22,270
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, ratio		6.50%	6.50%
Total risk-based capital, actual, amount		$ 44,068	$ 42,007
Total risk-based capital, actual, ratio		11.78%	12.26%
Total risk-based capital for capital adquacy purposes, amount, without capital conservation buffer	[1]	$ 29,922	$ 27,410
Total risk-based capital for capital adquacy purposes, ratio, without capital conservation buffer	[1]	8.00%	8.00%
Total risk-based capital for capital adquacy purposes, amount	[1]	$ 34,598	$ 29,551
Total risk-based capital for capital adquacy purposes, ratio	[1]	9.25%	8.625%
Total risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 37,403	$ 34,262
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		$ 39,384	$ 37,716
Tier 1 risk-based capital, actual, ratio		10.53%	11.01%
Tier 1 risk-based capital for capital adequacy purposes, amount, without capital conservation buffer	[1]	$ 22,442	$ 20,558
Tier 1 risk-based capital for capital adequacy purposes, ratio, without capital conservation buffer	[1]	6.00%	6.00%
Tier 1 risk-based capital for capital adequacy purposes, amount	[1]	$ 27,117	$ 22,699
Tier 1 risk-based capital for capital adequacy purposes, ratio	[1]	7.25%	6.625%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 29,922	$ 27,410
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, ratio		8.00%	8.00%
Tier 1 leverage, actual, amount		$ 39,384	$ 37,716
Tier 1 leverage, actual, ratio		9.63%	9.57%
Tier 1 leverage for capital adequacy purposes, amount, without capital conservation buffer	[1]	$ 16,354	$ 15,772
Tier 1 leverage for capital adequacy purposes, ratio, without capital conservation buffer	[1]	4.00%	4.00%
Tier 1 leverage for capital adequacy purposes, amount	[1]	$ 16,354	$ 15,772
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		$ 20,442	$ 19,716

[1] The minimums under Basel III increase 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).