Note 7 - Regulatory Capital Requirements - Capital Requirements (Details) - USD ($)		Sep. 30, 2017	Dec. 31, 2016
Total risk-based capital, actual, amount		$ 356,559	$ 327,440
Total risk-based capital, actual, ratio		11.49%	11.56%
Total risk-based capital for capital adquacy purposes, amount, without capital conservation buffer		$ 248,360	$ 226,587
Total risk-based capital for capital adquacy purposes, ratio, without capital conservation buffer		8.00%	8.00%
Total risk-based capital for capital adquacy purposes, amount	[1]	$ 287,166	$ 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		$ 310,450	$ 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		$ 321,213	$ 296,366
Tier 1 risk-based capital, actual, ratio		10.35%	10.46%
Tier 1 risk-based capital for capital adequacy purposes, amount, without capital conservation buffer		$ 186,270	$ 169,940
Tier 1 risk-based capital for capital adequacy purposes, ratio, without capital conservation buffer		6.00%	6.00%
Tier 1 risk-based capital for capital adequacy purposes, amount	[1]	$ 225,076	$ 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		$ 248,360	$ 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		$ 321,213	$ 296,366
Tier 1 leverage, actual, ratio		9.23%	9.10%
Tier 1 leverage for capital adequacy purposes, amount, without capital conservation buffer		$ 139,146	$ 130,229
Tier 1 leverage for capital adequacy purposes, ratio, without capital conservation buffer		4.00%	4.00%
Tier 1 leverage for capital adequacy purposes, amount	[1]	$ 139,146	$ 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		$ 173,932	$ 162,787
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 289,612	$ 266,419
Common equity Tier 1, actual ratio		9.33%	9.41%
Common equity Tier 1 for capital adequacy purposes, amount, without capital conservation buffer		$ 139,703	$ 127,455
Common equity Tier 1 for capital adequacy purposes, ratio, without capital conservation buffer		4.50%	4.50%
Common equity Tier 1 for capital adequacy purposes, amount	[1]	$ 178,509	$ 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		$ 201,793	$ 184,102
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		$ 152,635	$ 142,990
Total risk-based capital, actual, ratio		12.25%	12.27%
Total risk-based capital for capital adquacy purposes, amount, without capital conservation buffer		$ 99,693	$ 93,212
Total risk-based capital for capital adquacy purposes, ratio, without capital conservation buffer		8.00%	8.00%
Total risk-based capital for capital adquacy purposes, amount	[1]	$ 115,270	$ 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		$ 124,616	$ 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		$ 138,453	$ 129,524
Tier 1 risk-based capital, actual, ratio		11.11%	11.12%
Tier 1 risk-based capital for capital adequacy purposes, amount, without capital conservation buffer		$ 74,770	$ 69,909
Tier 1 risk-based capital for capital adequacy purposes, ratio, without capital conservation buffer		6.00%	6.00%
Tier 1 risk-based capital for capital adequacy purposes, amount	[1]	$ 90,347	$ 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		$ 99,693	$ 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		$ 138,453	$ 129,524
Tier 1 leverage, actual, ratio		9.40%	9.18%
Tier 1 leverage for capital adequacy purposes, amount, without capital conservation buffer		$ 58,913	$ 56,445
Tier 1 leverage for capital adequacy purposes, ratio, without capital conservation buffer		4.00%	4.00%
Tier 1 leverage for capital adequacy purposes, amount	[1]	$ 58,913	$ 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		$ 73,642	$ 70,556
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 138,453	$ 129,524
Common equity Tier 1, actual ratio		11.11%	11.12%
Common equity Tier 1 for capital adequacy purposes, amount, without capital conservation buffer		$ 56,077	$ 52,432
Common equity Tier 1 for capital adequacy purposes, ratio, without capital conservation buffer		4.50%	4.50%
Common equity Tier 1 for capital adequacy purposes, amount	[1]	$ 71,654	$ 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		$ 81,001	$ 75,735
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		$ 114,234	$ 106,791
Total risk-based capital, actual, ratio		12.16%	12.82%
Total risk-based capital for capital adquacy purposes, amount, without capital conservation buffer		$ 75,150	$ 66,623
Total risk-based capital for capital adquacy purposes, ratio, without capital conservation buffer		8.00%	8.00%
Total risk-based capital for capital adquacy purposes, amount	[1]	$ 86,893	$ 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		$ 93,938	$ 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		$ 102,545	$ 96,369
Tier 1 risk-based capital, actual, ratio		10.92%	11.57%
Tier 1 risk-based capital for capital adequacy purposes, amount, without capital conservation buffer		$ 56,363	$ 49,968
Tier 1 risk-based capital for capital adequacy purposes, ratio, without capital conservation buffer		6.00%	6.00%
Tier 1 risk-based capital for capital adequacy purposes, amount	[1]	$ 68,105	$ 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		$ 75,150	$ 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		$ 102,545	$ 96,369
Tier 1 leverage, actual, ratio		10.27%	10.69%
Tier 1 leverage for capital adequacy purposes, amount, without capital conservation buffer		$ 39,950	$ 36,061
Tier 1 leverage for capital adequacy purposes, ratio, without capital conservation buffer		4.00%	4.00%
Tier 1 leverage for capital adequacy purposes, amount	[1]	$ 39,950	$ 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		$ 49,938	$ 45,076
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 102,545	$ 96,369
Common equity Tier 1, actual ratio		10.92%	11.57%
Common equity Tier 1 for capital adequacy purposes, amount, without capital conservation buffer		$ 42,272	$ 37,476
Common equity Tier 1 for capital adequacy purposes, ratio, without capital conservation buffer		4.50%	4.50%
Common equity Tier 1 for capital adequacy purposes, amount	[1]	$ 54,014	$ 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		$ 61,060	$ 54,132
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, ratio		6.50%	6.50%
Community State Bank [Member]
Total risk-based capital, actual, amount		$ 67,071	$ 68,216
Total risk-based capital, actual, ratio		12.83%	13.81%
Total risk-based capital for capital adquacy purposes, amount, without capital conservation buffer		$ 41,837	$ 39,521
Total risk-based capital for capital adquacy purposes, ratio, without capital conservation buffer		8.00%	8.00%
Total risk-based capital for capital adquacy purposes, amount	[1]	$ 48,374	$ 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		$ 52,296	$ 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		$ 63,356	$ 66,746
Tier 1 risk-based capital, actual, ratio		12.11%	13.51%
Tier 1 risk-based capital for capital adequacy purposes, amount, without capital conservation buffer		$ 31,378	$ 29,641
Tier 1 risk-based capital for capital adequacy purposes, ratio, without capital conservation buffer		6.00%	6.00%
Tier 1 risk-based capital for capital adequacy purposes, amount	[1]	$ 37,915	$ 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		$ 41,837	$ 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		$ 63,356	$ 66,746
Tier 1 leverage, actual, ratio		10.14%	11.75%
Tier 1 leverage for capital adequacy purposes, amount, without capital conservation buffer		$ 24,991	$ 22,726
Tier 1 leverage for capital adequacy purposes, ratio, without capital conservation buffer		4.00%	4.00%
Tier 1 leverage for capital adequacy purposes, amount	[1]	$ 24,991	$ 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		$ 31,239	$ 28,408
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 63,356	$ 66,746
Common equity Tier 1, actual ratio		12.11%	13.51%
Common equity Tier 1 for capital adequacy purposes, amount, without capital conservation buffer		$ 23,533	$ 22,231
Common equity Tier 1 for capital adequacy purposes, ratio, without capital conservation buffer		4.50%	4.50%
Common equity Tier 1 for capital adequacy purposes, amount	[1]	$ 30,070	$ 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		$ 33,992	$ 32,111
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		$ 45,031	$ 42,007
Total risk-based capital, actual, ratio		11.48%	12.26%
Total risk-based capital for capital adquacy purposes, amount, without capital conservation buffer		$ 31,394	$ 27,410
Total risk-based capital for capital adquacy purposes, ratio, without capital conservation buffer		8.00%	8.00%
Total risk-based capital for capital adquacy purposes, amount	[1]	$ 36,299	$ 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		$ 39,243	$ 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		$ 40,120	$ 37,716
Tier 1 risk-based capital, actual, ratio		10.22%	11.01%
Tier 1 risk-based capital for capital adequacy purposes, amount, without capital conservation buffer		$ 23,546	$ 20,558
Tier 1 risk-based capital for capital adequacy purposes, ratio, without capital conservation buffer		6.00%	6.00%
Tier 1 risk-based capital for capital adequacy purposes, amount	[1]	$ 28,451	$ 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		$ 31,394	$ 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		$ 40,120	$ 37,716
Tier 1 leverage, actual, ratio		9.26%	9.57%
Tier 1 leverage for capital adequacy purposes, amount, without capital conservation buffer		$ 17,328	$ 15,772
Tier 1 leverage for capital adequacy purposes, ratio, without capital conservation buffer		4.00%	4.00%
Tier 1 leverage for capital adequacy purposes, amount	[1]	$ 17,328	$ 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		$ 21,660	$ 19,716
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 40,120	$ 37,716
Common equity Tier 1, actual ratio		10.22%	11.01%
Common equity Tier 1 for capital adequacy purposes, amount, without capital conservation buffer		$ 17,659	$ 15,418
Common equity Tier 1 for capital adequacy purposes, ratio, without capital conservation buffer		4.50%	4.50%
Common equity Tier 1 for capital adequacy purposes, amount	[1]	$ 22,564	$ 17,759
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		$ 25,508	$ 22,270
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, ratio		6.50%	6.50%

[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).