Regulatory Capital Requirements and Restrictions on Subsidiary Dividends (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Total Capital (to Risk-Weighted Assets)
Actual - Amount	$ 887,607	$ 812,568
Actual - Ratio	14.01%	13.74%
For Capital Adequacy Purposes - Amount	$ 506,865	$ 473,282
For Capital Adequacy Purposes - Ratio	8.00%	8.00%
Tier 1 Capital (to Risk-Weighted Assets)
Actual - Amount	$ 756,056	$ 683,706
Actual - Ratio	11.93%	11.56%
For Capital Adequacy Purposes - Amount	$ 380,148	$ 354,980
For Capital Adequacy Purposes - Ratio	6.00%	6.00%
Common Equity Tier 1 (to Risk-Weighted Assets)
Actual - Amount	$ 639,467	$ 487,132
Actual - Ratio	10.09%	8.23%
For Capital Adequacy Purposes - Amount	$ 285,111	$ 266,324
For Capital Adequacy Purposes - Ratio	4.50%	4.50%
Tier 1 Capital (to Average Assets)
Actual - Amount	$ 756,056	$ 683,706
Actual - Ratio	9.28%	9.58%
For Capital Adequacy Purposes - Amount	$ 325,894	$ 285,606
For Capital Adequacy Purposes - Ratio	4.00%	4.00%
Minimum Capital Requirement
Tier 1 Capital (to Average Assets)
Retained earnings available for dividend payments	$ 308,900
Capital Requirement to Remain Well Capitalized
Tier 1 Capital (to Average Assets)
Retained earnings available for dividend payments	182,100
Dubuque Bank and Trust Company
Total Capital (to Risk-Weighted Assets)
Actual - Amount	$ 150,692	$ 149,699
Actual - Ratio	12.76%	11.92%
For Capital Adequacy Purposes - Amount	$ 94,494	$ 100,489
For Capital Adequacy Purposes - Ratio	8.00%	8.00%
To Be Well Capitalized Under Prompt Corrective Action - Amount	$ 118,117	$ 125,612
To Be Well Capitalized Under Prompt Corrective Action - Ratio	10.00%	10.00%
Tier 1 Capital (to Risk-Weighted Assets)
Actual - Amount	$ 140,970	$ 139,487
Actual - Ratio	11.93%	11.10%
For Capital Adequacy Purposes - Amount	$ 70,870	$ 75,367
For Capital Adequacy Purposes - Ratio	6.00%	6.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 94,494	$ 100,489
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	8.00%	8.00%
Common Equity Tier 1 (to Risk-Weighted Assets)
Actual - Amount	$ 140,970	$ 139,487
Actual - Ratio	11.93%	11.10%
For Capital Adequacy Purposes - Amount	$ 53,153	$ 56,525
For Capital Adequacy Purposes - Ratio	4.50%	4.50%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 76,776	$ 81,648
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	6.50%	6.50%
Tier 1 Capital (to Average Assets)
Actual - Amount	$ 140,970	$ 139,487
Actual - Ratio	9.41%	9.08%
For Capital Adequacy Purposes - Amount	$ 59,896	$ 61,456
For Capital Adequacy Purposes - Ratio	4.00%	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 74,870	$ 76,820
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	5.00%	5.00%
Illinois Bank & Trust
Total Capital (to Risk-Weighted Assets)
Actual - Amount	$ 70,808	$ 68,155
Actual - Ratio	11.83%	11.71%
For Capital Adequacy Purposes - Amount	$ 47,884	$ 46,579
For Capital Adequacy Purposes - Ratio	8.00%	8.00%
To Be Well Capitalized Under Prompt Corrective Action - Amount	$ 59,856	$ 58,224
To Be Well Capitalized Under Prompt Corrective Action - Ratio	10.00%	10.00%
Tier 1 Capital (to Risk-Weighted Assets)
Actual - Amount	$ 66,101	$ 62,436
Actual - Ratio	11.04%	10.72%
For Capital Adequacy Purposes - Amount	$ 35,913	$ 34,934
For Capital Adequacy Purposes - Ratio	6.00%	6.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 47,884	$ 46,579
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	8.00%	8.00%
Common Equity Tier 1 (to Risk-Weighted Assets)
Actual - Amount	$ 66,101	$ 62,436
Actual - Ratio	11.04%	10.72%
For Capital Adequacy Purposes - Amount	$ 26,935	$ 26,201
For Capital Adequacy Purposes - Ratio	4.50%	4.50%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 38,906	$ 37,846
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	6.50%	6.50%
Tier 1 Capital (to Average Assets)
Actual - Amount	$ 66,101	$ 62,436
Actual - Ratio	8.80%	8.10%
For Capital Adequacy Purposes - Amount	$ 30,059	$ 30,820
For Capital Adequacy Purposes - Ratio	4.00%	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 37,573	$ 38,525
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	5.00%	5.00%
Wisconsin Bank & Trust
Total Capital (to Risk-Weighted Assets)
Actual - Amount	$ 109,069	$ 108,739
Actual - Ratio	14.35%	12.75%
For Capital Adequacy Purposes - Amount	$ 60,819	$ 68,229
For Capital Adequacy Purposes - Ratio	8.00%	8.00%
To Be Well Capitalized Under Prompt Corrective Action - Amount	$ 76,024	$ 85,286
To Be Well Capitalized Under Prompt Corrective Action - Ratio	10.00%	10.00%
Tier 1 Capital (to Risk-Weighted Assets)
Actual - Amount	$ 102,523	$ 102,643
Actual - Ratio	13.49%	12.04%
For Capital Adequacy Purposes - Amount	$ 45,614	$ 51,171
For Capital Adequacy Purposes - Ratio	6.00%	6.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 60,819	$ 68,229
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	8.00%	8.00%
Common Equity Tier 1 (to Risk-Weighted Assets)
Actual - Amount	$ 102,523	$ 102,643
Actual - Ratio	13.49%	12.04%
For Capital Adequacy Purposes - Amount	$ 34,211	$ 38,379
For Capital Adequacy Purposes - Ratio	4.50%	4.50%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 49,416	$ 55,436
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	6.50%	6.50%
Tier 1 Capital (to Average Assets)
Actual - Amount	$ 102,523	$ 102,643
Actual - Ratio	9.96%	9.48%
For Capital Adequacy Purposes - Amount	$ 41,155	$ 43,312
For Capital Adequacy Purposes - Ratio	4.00%	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 51,443	$ 54,141
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	5.00%	5.00%
New Mexico Bank & Trust
Total Capital (to Risk-Weighted Assets)
Actual - Amount	$ 119,246	$ 108,878
Actual - Ratio	11.20%	11.18%
For Capital Adequacy Purposes - Amount	$ 85,208	$ 77,944
For Capital Adequacy Purposes - Ratio	8.00%	8.00%
To Be Well Capitalized Under Prompt Corrective Action - Amount	$ 106,510	$ 97,430
To Be Well Capitalized Under Prompt Corrective Action - Ratio	10.00%	10.00%
Tier 1 Capital (to Risk-Weighted Assets)
Actual - Amount	$ 109,185	$ 101,174
Actual - Ratio	10.25%	10.38%
For Capital Adequacy Purposes - Amount	$ 63,906	$ 58,458
For Capital Adequacy Purposes - Ratio	6.00%	6.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 85,208	$ 77,944
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	8.00%	8.00%
Common Equity Tier 1 (to Risk-Weighted Assets)
Actual - Amount	$ 109,185	$ 101,174
Actual - Ratio	10.25%	10.38%
For Capital Adequacy Purposes - Amount	$ 47,929	$ 43,844
For Capital Adequacy Purposes - Ratio	4.50%	4.50%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 69,231	$ 63,330
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	6.50%	6.50%
Tier 1 Capital (to Average Assets)
Actual - Amount	$ 109,185	$ 101,174
Actual - Ratio	8.16%	7.76%
For Capital Adequacy Purposes - Amount	$ 53,529	$ 52,167
For Capital Adequacy Purposes - Ratio	4.00%	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 66,911	$ 65,209
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	5.00%	5.00%
Arizona Bank & Trust
Total Capital (to Risk-Weighted Assets)
Actual - Amount	$ 58,741	$ 54,026
Actual - Ratio	14.64%	12.66%
For Capital Adequacy Purposes - Amount	$ 32,108	$ 34,141
For Capital Adequacy Purposes - Ratio	8.00%	8.00%
To Be Well Capitalized Under Prompt Corrective Action - Amount	$ 40,135	$ 42,677
To Be Well Capitalized Under Prompt Corrective Action - Ratio	10.00%	10.00%
Tier 1 Capital (to Risk-Weighted Assets)
Actual - Amount	$ 54,970	$ 50,608
Actual - Ratio	13.70%	11.86%
For Capital Adequacy Purposes - Amount	$ 24,081	$ 25,606
For Capital Adequacy Purposes - Ratio	6.00%	6.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 32,108	$ 34,141
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	8.00%	8.00%
Common Equity Tier 1 (to Risk-Weighted Assets)
Actual - Amount	$ 54,970	$ 50,608
Actual - Ratio	13.70%	11.86%
For Capital Adequacy Purposes - Amount	$ 18,061	$ 19,204
For Capital Adequacy Purposes - Ratio	4.50%	4.50%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 26,088	$ 27,740
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	6.50%	6.50%
Tier 1 Capital (to Average Assets)
Actual - Amount	$ 54,970	$ 50,608
Actual - Ratio	9.59%	8.50%
For Capital Adequacy Purposes - Amount	$ 22,922	$ 23,802
For Capital Adequacy Purposes - Ratio	4.00%	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 28,653	$ 29,752
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	5.00%	5.00%
Rocky Mountain Bank
Total Capital (to Risk-Weighted Assets)
Actual - Amount	$ 50,188	$ 48,543
Actual - Ratio	13.72%	12.14%
For Capital Adequacy Purposes - Amount	$ 29,254	$ 31,989
For Capital Adequacy Purposes - Ratio	8.00%	8.00%
To Be Well Capitalized Under Prompt Corrective Action - Amount	$ 36,568	$ 39,987
To Be Well Capitalized Under Prompt Corrective Action - Ratio	10.00%	10.00%
Tier 1 Capital (to Risk-Weighted Assets)
Actual - Amount	$ 46,702	$ 45,255
Actual - Ratio	12.77%	11.32%
For Capital Adequacy Purposes - Amount	$ 21,941	$ 23,992
For Capital Adequacy Purposes - Ratio	6.00%	6.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 29,254	$ 31,989
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	8.00%	8.00%
Common Equity Tier 1 (to Risk-Weighted Assets)
Actual - Amount	$ 46,702	$ 45,255
Actual - Ratio	12.77%	11.32%
For Capital Adequacy Purposes - Amount	$ 16,455	$ 17,994
For Capital Adequacy Purposes - Ratio	4.50%	4.50%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 23,769	$ 25,991
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	6.50%	6.50%
Tier 1 Capital (to Average Assets)
Actual - Amount	$ 46,702	$ 45,255
Actual - Ratio	9.79%	9.24%
For Capital Adequacy Purposes - Amount	$ 19,078	$ 19,589
For Capital Adequacy Purposes - Ratio	4.00%	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 23,848	$ 24,486
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	5.00%	5.00%
Centennial Bank and Trust
Total Capital (to Risk-Weighted Assets)
Actual - Amount	$ 83,615	$ 14,324
Actual - Ratio	13.25%	11.26%
For Capital Adequacy Purposes - Amount	$ 50,475	$ 10,180
For Capital Adequacy Purposes - Ratio	8.00%	8.00%
To Be Well Capitalized Under Prompt Corrective Action - Amount	$ 63,094	$ 12,725
To Be Well Capitalized Under Prompt Corrective Action - Ratio	10.00%	10.00%
Tier 1 Capital (to Risk-Weighted Assets)
Actual - Amount	$ 81,260	$ 13,410
Actual - Ratio	12.88%	10.54%
For Capital Adequacy Purposes - Amount	$ 37,857	$ 7,635
For Capital Adequacy Purposes - Ratio	6.00%	6.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 50,475	$ 10,180
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	8.00%	8.00%
Common Equity Tier 1 (to Risk-Weighted Assets)
Actual - Amount	$ 81,260	$ 13,410
Actual - Ratio	12.88%	10.54%
For Capital Adequacy Purposes - Amount	$ 28,392	$ 5,726
For Capital Adequacy Purposes - Ratio	4.50%	4.50%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 41,011	$ 8,271
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	6.50%	6.50%
Tier 1 Capital (to Average Assets)
Actual - Amount	$ 81,260	$ 13,410
Actual - Ratio	9.33%	8.67%
For Capital Adequacy Purposes - Amount	$ 34,827	$ 6,190
For Capital Adequacy Purposes - Ratio	4.00%	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 43,534	$ 7,738
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	5.00%	5.00%
Minnesota Bank & Trust
Total Capital (to Risk-Weighted Assets)
Actual - Amount	$ 21,693	$ 19,129
Actual - Ratio	11.86%	11.14%
For Capital Adequacy Purposes - Amount	$ 14,628	$ 13,740
For Capital Adequacy Purposes - Ratio	8.00%	8.00%
To Be Well Capitalized Under Prompt Corrective Action - Amount	$ 18,285	$ 17,175
To Be Well Capitalized Under Prompt Corrective Action - Ratio	10.00%	10.00%
Tier 1 Capital (to Risk-Weighted Assets)
Actual - Amount	$ 20,315	$ 17,621
Actual - Ratio	11.11%	10.26%
For Capital Adequacy Purposes - Amount	$ 10,971	$ 10,305
For Capital Adequacy Purposes - Ratio	6.00%	6.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 14,628	$ 13,740
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	8.00%	8.00%
Common Equity Tier 1 (to Risk-Weighted Assets)
Actual - Amount	$ 20,315	$ 17,621
Actual - Ratio	11.11%	10.26%
For Capital Adequacy Purposes - Amount	$ 8,228	$ 7,729
For Capital Adequacy Purposes - Ratio	4.50%	4.50%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 11,885	$ 11,163
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	6.50%	6.50%
Tier 1 Capital (to Average Assets)
Actual - Amount	$ 20,315	$ 17,621
Actual - Ratio	8.72%	8.72%
For Capital Adequacy Purposes - Amount	$ 9,315	$ 8,082
For Capital Adequacy Purposes - Ratio	4.00%	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 11,644	$ 10,102
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	5.00%	5.00%
Morrill & Janes Bank and Trust Company
Total Capital (to Risk-Weighted Assets)
Actual - Amount	$ 85,649	$ 78,265
Actual - Ratio	12.36%	11.58%
For Capital Adequacy Purposes - Amount	$ 55,433	$ 54,057
For Capital Adequacy Purposes - Ratio	8.00%	8.00%
To Be Well Capitalized Under Prompt Corrective Action - Amount	$ 69,292	$ 67,571
To Be Well Capitalized Under Prompt Corrective Action - Ratio	10.00%	10.00%
Tier 1 Capital (to Risk-Weighted Assets)
Actual - Amount	$ 78,615	$ 72,387
Actual - Ratio	11.35%	10.71%
For Capital Adequacy Purposes - Amount	$ 41,575	$ 40,543
For Capital Adequacy Purposes - Ratio	6.00%	6.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 55,433	$ 54,057
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	8.00%	8.00%
Common Equity Tier 1 (to Risk-Weighted Assets)
Actual - Amount	$ 78,615	$ 72,387
Actual - Ratio	11.35%	10.71%
For Capital Adequacy Purposes - Amount	$ 31,181	$ 30,407
For Capital Adequacy Purposes - Ratio	4.50%	4.50%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 45,040	$ 43,921
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	6.50%	6.50%
Tier 1 Capital (to Average Assets)
Actual - Amount	$ 78,615	$ 72,387
Actual - Ratio	9.12%	8.07%
For Capital Adequacy Purposes - Amount	$ 34,463	$ 35,869
For Capital Adequacy Purposes - Ratio	4.00%	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 43,079	$ 44,836
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	5.00%	5.00%
Premier Valley Bank
Total Capital (to Risk-Weighted Assets)
Actual - Amount	$ 66,132	$ 59,729
Actual - Ratio	14.44%	12.29%
For Capital Adequacy Purposes - Amount	$ 36,649	$ 38,572
For Capital Adequacy Purposes - Ratio	8.00%	8.00%
To Be Well Capitalized Under Prompt Corrective Action - Amount	$ 45,811	$ 48,215
To Be Well Capitalized Under Prompt Corrective Action - Ratio	10.00%	10.00%
Tier 1 Capital (to Risk-Weighted Assets)
Actual - Amount	$ 64,735	$ 59,144
Actual - Ratio	14.13%	12.27%
For Capital Adequacy Purposes - Amount	$ 27,487	$ 28,929
For Capital Adequacy Purposes - Ratio	6.00%	6.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 36,649	$ 38,572
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	8.00%	8.00%
Common Equity Tier 1 (to Risk-Weighted Assets)
Actual - Amount	$ 64,735	$ 59,144
Actual - Ratio	14.13%	12.27%
For Capital Adequacy Purposes - Amount	$ 20,615	$ 21,697
For Capital Adequacy Purposes - Ratio	4.50%	4.50%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 29,777	$ 31,339
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	6.50%	6.50%
Tier 1 Capital (to Average Assets)
Actual - Amount	$ 64,735	$ 59,144
Actual - Ratio	10.91%	8.48%
For Capital Adequacy Purposes - Amount	$ 23,729	$ 27,890
For Capital Adequacy Purposes - Ratio	4.00%	4.00%
To Be Well Capitalized Under Prompt Corrective Action Provisions - Amount	$ 29,661	$ 34,863
To Be Well Capitalized Under Prompt Corrective Action Provisions - Ratio	5.00%	5.00%