Regulatory Matters - Actual and Required Capital Ratios of Bank (Detail) $ in Thousands	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Consolidated
Schedule of Capitalization [Line Items]
Total Capital (to Risk Weighted Assets)	$ 1,152,530	$ 1,115,257
Tier 1 Capital (to Risk Weighted Assets)	1,010,295	974,325
Common Equity Tier 1 Capital (to Risk Weighted Assets)	953,407	917,565
Tier 1 Capital (to Average Assets)	$ 1,010,295	$ 974,325
Total Capital Ratio (to Risk Weighted Assets)	0.1447	0.1419
Tier 1 Capital Ratio (to Risk Weighted Assets)	0.1269	0.1240
Common Equity Tier 1 Capital Ratio (to Risk Weighted Assets)	0.1197	0.1167
Tier 1 Capital Ratio (to Average Assets)	0.1041	0.1014
Consolidated \| Basel III Fully Phased In
Schedule of Capitalization [Line Items]
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement	$ 836,038	$ 825,234
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement	676,793	668,047
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement	557,359	550,156
Tier 1 Capital (to Average Assets), Minimum Capital Requirement	$ 388,260	$ 384,337
Total Capital Ratio (to Risk Weighted Assets), Minimum Capital Requirement	0.1050	0.1050
Tier 1 Capital Ratio (to Risk Weighted Assets), Minimum Capital Requirement	0.0850	0.0850
Common Equity Tier 1 Capital Ratio (to Risk Weighted Assets), Minimum Capital Requirement	7.00%	7.00%
Tier 1 Capital Ratio (to Average Assets), Minimum Capital Requirement	0.0400	0.0400
Tri Counties Bank
Schedule of Capitalization [Line Items]
Total Capital (to Risk Weighted Assets)	$ 1,147,002	$ 1,107,941
Tier 1 Capital (to Risk Weighted Assets)	1,047,217	1,009,577
Common Equity Tier 1 Capital (to Risk Weighted Assets)	1,047,217	1,009,577
Tier 1 Capital (to Average Assets)	$ 1,047,217	$ 1,009,577
Total Capital Ratio (to Risk Weighted Assets)	0.1441	0.1410
Tier 1 Capital Ratio (to Risk Weighted Assets)	0.1316	0.1285
Common Equity Tier 1 Capital Ratio (to Risk Weighted Assets)	0.1316	0.1285
Tier 1 Capital Ratio (to Average Assets)	0.1079	0.1051
Total Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions	$ 796,041	$ 785,751
Capital Required to be Well Capitalized to Risk Weighted Assets	0.1000	0.1000
Tier 1 Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions	$ 636,833	$ 628,601
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	0.0800	0.0800
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions	$ 517,427	$ 510,738
Common Equity Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	6.50%	6.50%
Tier 1 Capital (to Average Assets), Minimum To Be Well Capitalized Under Prompt Corrective Action Provisions	$ 485,271	$ 480,183
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	0.0500	0.0500
Tri Counties Bank \| Basel III Fully Phased In
Schedule of Capitalization [Line Items]
Total Capital (to Risk Weighted Assets), Minimum Capital Requirement	$ 835,843	$ 825,039
Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement	676,635	667,888
Common Equity Tier 1 Capital (to Risk Weighted Assets), Minimum Capital Requirement	557,229	550,026
Tier 1 Capital (to Average Assets), Minimum Capital Requirement	$ 388,217	$ 384,146
Total Capital Ratio (to Risk Weighted Assets), Minimum Capital Requirement	0.1050	0.1050
Tier 1 Capital Ratio (to Risk Weighted Assets), Minimum Capital Requirement	0.0850	0.0850
Common Equity Tier 1 Capital Ratio (to Risk Weighted Assets), Minimum Capital Requirement	7.00%	7.00%
Tier 1 Capital Ratio (to Average Assets), Minimum Capital Requirement	0.0400	0.0400

Common Equity Tier One Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480696/942-505-50-1

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