Note 7 - Regulatory Capital Requirements and Restrictions on Dividends - Capital Requirements (Details) - USD ($) $ in Thousands		Mar. 31, 2018	Dec. 31, 2017
Total risk-based capital, actual, amount		$ 395,160	$ 383,282
Total risk-based capital, actual, ratio		11.25%	11.15%
Total risk-based capital for capital adquacy purposes, amount, without capital conservation buffer		$ 281,109	$ 275,090
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]	$ 346,994	$ 318,073
Total risk-based capital for capital adquacy purposes, ratio	[1]	9.875%	9.25%
Total risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 351,386	$ 343,862
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		$ 358,627	$ 348,530
Tier 1 risk-based capital, actual, ratio		10.21%	10.14%
Tier 1 risk-based capital for capital adequacy purposes, amount, without capital conservation buffer		$ 210,832	$ 206,317
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]	$ 276,717	$ 249,300
Tier 1 risk-based capital for capital adequacy purposes, ratio	[1]	7.875%	7.25%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 281,109	$ 275,090
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, ratio		8.00%	8.00%
Tier 1 leverage, actual, amount		$ 358,627	$ 348,530
Tier 1 leverage, actual, ratio		9.08%	8.98%
Tier 1 leverage for capital adequacy purposes, amount, without capital conservation buffer		$ 157,993	$ 155,256
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]	$ 157,993	$ 155,256
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		$ 197,491	$ 194,070
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 321,093	$ 313,012
Common equity Tier 1, actual ratio		9.14%	9.10%
Common equity Tier 1 for capital adequacy purposes, amount, without capital conservation buffer		$ 158,124	$ 154,738
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]	$ 224,009	$ 197,721
Common equity Tier 1 for capital adequacy purposes, ratio	[1]	6.375%	5.75%
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, amount		$ 228,401	$ 223,510
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		$ 160,996	$ 160,112
Total risk-based capital, actual, ratio		12.32%	12.35%
Total risk-based capital for capital adquacy purposes, amount, without capital conservation buffer		$ 104,544	$ 103,711
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]	$ 129,047	$ 119,916
Total risk-based capital for capital adquacy purposes, ratio	[1]	9.875%	9.25%
Total risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 130,680	$ 129,639
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		$ 147,618	$ 147,472
Tier 1 risk-based capital, actual, ratio		11.30%	11.38%
Tier 1 risk-based capital for capital adequacy purposes, amount, without capital conservation buffer		$ 78,408	$ 77,783
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]	$ 102,911	$ 93,988
Tier 1 risk-based capital for capital adequacy purposes, ratio	[1]	7.875%	7.25%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 104,544	$ 103,711
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, ratio		8.00%	8.00%
Tier 1 leverage, actual, amount		$ 147,618	$ 147,472
Tier 1 leverage, actual, ratio		9.63%	9.52%
Tier 1 leverage for capital adequacy purposes, amount, without capital conservation buffer		$ 61,343	$ 61,985
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]	$ 61,343	$ 61,985
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		$ 76,678	$ 77,481
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 147,618	$ 147,472
Common equity Tier 1, actual ratio		11.30%	11.38%
Common equity Tier 1 for capital adequacy purposes, amount, without capital conservation buffer		$ 58,806	$ 58,337
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]	$ 83,309	$ 74,542
Common equity Tier 1 for capital adequacy purposes, ratio	[1]	6.375%	5.75%
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, amount		$ 84,942	$ 84,265
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		$ 142,034	$ 138,492
Total risk-based capital, actual, ratio		11.96%	11.88%
Total risk-based capital for capital adquacy purposes, amount, without capital conservation buffer		$ 94,998	$ 93,272
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]	$ 117,264	$ 107,846
Total risk-based capital for capital adquacy purposes, ratio	[1]	9.875%	9.25%
Total risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 118,748	$ 116,590
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		$ 129,507	$ 126,601
Tier 1 risk-based capital, actual, ratio		10.91%	10.86%
Tier 1 risk-based capital for capital adequacy purposes, amount, without capital conservation buffer		$ 71,249	$ 69,954
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]	$ 93,514	$ 84,528
Tier 1 risk-based capital for capital adequacy purposes, ratio	[1]	7.875%	7.25%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 94,998	$ 93,272
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, ratio		8.00%	8.00%
Tier 1 leverage, actual, amount		$ 129,507	$ 126,601
Tier 1 leverage, actual, ratio		9.87%	11.68%
Tier 1 leverage for capital adequacy purposes, amount, without capital conservation buffer		$ 52,483	$ 43,348
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]	$ 52,483	$ 43,348
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		$ 65,603	$ 54,185
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 129,507	$ 126,601
Common equity Tier 1, actual ratio		10.91%	10.86%
Common equity Tier 1 for capital adequacy purposes, amount, without capital conservation buffer		$ 53,437	$ 52,465
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]	$ 75,702	$ 67,039
Common equity Tier 1 for capital adequacy purposes, ratio	[1]	6.375%	5.75%
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, amount		$ 77,186	$ 75,783
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		$ 67,996	$ 66,271
Total risk-based capital, actual, ratio		11.39%	11.71%
Total risk-based capital for capital adquacy purposes, amount, without capital conservation buffer		$ 47,738	$ 45,293
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]	$ 58,926	$ 52,370
Total risk-based capital for capital adquacy purposes, ratio	[1]	9.875%	9.25%
Total risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 59,672	$ 56,616
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		$ 63,105	$ 61,941
Tier 1 risk-based capital, actual, ratio		10.58%	10.94%
Tier 1 risk-based capital for capital adequacy purposes, amount, without capital conservation buffer		$ 35,803	$ 33,970
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]	$ 46,992	$ 41,047
Tier 1 risk-based capital for capital adequacy purposes, ratio	[1]	7.875%	7.25%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 47,738	$ 45,293
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, ratio		8.00%	8.00%
Tier 1 leverage, actual, amount		$ 63,105	$ 61,941
Tier 1 leverage, actual, ratio		9.35%	9.77%
Tier 1 leverage for capital adequacy purposes, amount, without capital conservation buffer		$ 27,010	$ 25,354
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]	$ 27,010	$ 25,354
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		$ 33,763	$ 31,693
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 63,105	$ 61,941
Common equity Tier 1, actual ratio		10.58%	10.94%
Common equity Tier 1 for capital adequacy purposes, amount, without capital conservation buffer		$ 26,853	$ 25,477
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]	$ 38,041	$ 32,554
Common equity Tier 1 for capital adequacy purposes, ratio	[1]	6.375%	5.75%
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, amount		$ 38,787	$ 36,801
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		$ 46,567	$ 45,684
Total risk-based capital, actual, ratio		11.07%	11.28%
Total risk-based capital for capital adquacy purposes, amount, without capital conservation buffer		$ 33,644	$ 32,413
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]	$ 41,530	$ 37,477
Total risk-based capital for capital adquacy purposes, ratio	[1]	9.875%	9.25%
Total risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 42,055	$ 40,516
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		$ 41,305	$ 40,615
Tier 1 risk-based capital, actual, ratio		9.82%	10.02%
Tier 1 risk-based capital for capital adequacy purposes, amount, without capital conservation buffer		$ 25,233	$ 24,310
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]	$ 33,119	$ 29,374
Tier 1 risk-based capital for capital adequacy purposes, ratio	[1]	7.875%	7.25%
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, amount		$ 33,644	$ 32,413
Tier 1 risk-based capital to be well capitalized under prompt corrective action provisions, ratio		8.00%	8.00%
Tier 1 leverage, actual, amount		$ 41,305	$ 40,615
Tier 1 leverage, actual, ratio		8.93%	8.94%
Tier 1 leverage for capital adequacy purposes, amount, without capital conservation buffer		$ 18,498	$ 18,177
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]	$ 18,498	$ 18,177
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		$ 23,123	$ 22,721
Tier 1 leverage to be well capitalized under prompt corrective action provisions, ratio		5.00%	5.00%
Common equity Tier 1, actual, amount		$ 41,305	$ 40,615
Common equity Tier 1, actual ratio		9.82%	10.02%
Common equity Tier 1 for capital adequacy purposes, amount, without capital conservation buffer		$ 18,925	$ 18,232
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]	$ 26,810	$ 23,297
Common equity Tier 1 for capital adequacy purposes, ratio	[1]	6.375%	5.75%
Common equity Tier 1 to be well capitalized under prompt corrective action provisions, amount		$ 27,336	$ 26,335
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).