Regulatory Matters - Actual Capital Amounts and Ratios of Bank (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule of Capitalization [Line Items]
Total Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	$ 213,247	$ 201,201
Tier 1 Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	127,948	120,720
Tier 1 Capital (to Average Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	137,685	133,706
Total Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	10.00%	10.00%
Tier 1 Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.00%	6.00%
Tier 1 Capital (to Average Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	5.00%	5.00%
Parent [Member]
Schedule of Capitalization [Line Items]
Total Capital (to Risk Weighted Assets), Actual, Amount	315,581	297,429
Tier 1 Capital (to Risk Weighted Assets), Actual, Amount	288,740	272,071
Tier 1 Capital (to Average Assets), Actual, Amount	288,740	272,071
Total Capital (to Risk Weighted Assets), Actual, Ratio	14.79%	14.77%
Tier 1 Capital (to Risk Weighted Assets), Actual, Ratio	13.53%	13.51%
Tier 1 Capital (to Average Assets), Actual, Ratio	10.48%	10.17%
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	170,716	161,064
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	85,358	80,532
Tier 1 Capital (to Average Assets), Minimum Capital Requirement, Amount	110,197	107,017
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	8.00%	8.00%
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	4.00%	4.00%
Tier 1 Capital (to Average Assets), Minimum Capital Requirement, Ratio	4.00%	4.00%
Tri Countries Bank [Member]
Schedule of Capitalization [Line Items]
Total Capital (to Risk Weighted Assets), Actual, Amount	313,725	295,212
Tier 1 Capital (to Risk Weighted Assets), Actual, Amount	286,903	269,870
Tier 1 Capital (to Average Assets), Actual, Amount	286,903	269,870
Total Capital (to Risk Weighted Assets), Actual, Ratio	14.71%	14.67%
Tier 1 Capital (to Risk Weighted Assets), Actual, Ratio	13.45%	13.41%
Tier 1 Capital (to Average Assets), Actual, Ratio	10.42%	10.09%
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	170,597	160,961
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Amount	85,299	80,480
Tier 1 Capital (to Average Assets), Minimum Capital Requirement, Amount	$ 110,148	$ 106,965
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	8.00%	8.00%
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement, Ratio	4.00%	4.00%
Tier 1 Capital (to Average Assets), Minimum Capital Requirement, Ratio	4.00%	4.00%