Regulatory Matters (Detail) $ in Thousands	Mar. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)
Consolidated
Schedule of Capitalization [Line Items]
Total capital (to risk weighted assets)	$ 1,270,172	$ 1,258,218
Tier 1 capital (to risk weighted assets)	1,131,297	1,118,292
Common equity Tier 1 capital (to risk weighted assets)	1,073,574	1,060,690
Tier 1 capital (to average assets)	$ 1,131,297	$ 1,118,292
Total capital ratio (to risk weighted assets)	0.1578	0.1571
Tier 1 capital ratio (to risk weighted assets)	0.1405	0.1396
Common equity Tier 1 capital ratio (to risk weighted assets)	0.1334	0.1324
Tier 1 capital ratio (to average assets)	0.1173	0.1170
Consolidated \| Basel III Fully Phased In
Schedule of Capitalization [Line Items]
Total capital (to risk weighted assets), minimum capital requirement	$ 845,178	$ 840,943
Tier 1 capital (to risk weighted assets), minimum capital requirement	684,192	680,763
Common equity Tier 1 capital (to risk weighted assets), minimum capital requirement	563,452	560,628
Tier 1 capital (to average assets), minimum capital requirement	$ 385,935	$ 382,214
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)	$ 1,266,587	$ 1,248,802
Tier 1 capital (to risk weighted assets)	1,165,564	1,148,328
Common equity Tier 1 capital (to risk weighted assets)	1,165,564	1,148,328
Tier 1 capital (to average assets)	$ 1,165,564	$ 1,148,328
Total capital ratio (to risk weighted assets)	0.1574	0.1560
Tier 1 capital ratio (to risk weighted assets)	0.1448	0.1434
Common equity Tier 1 capital ratio (to risk weighted assets)	0.1448	0.1434
Tier 1 capital ratio (to average assets)	0.1208	0.1202
Total capital (to risk weighted assets), minimum to be well capitalized under prompt corrective action provisions	$ 804,735	$ 800,704
Tier 1 capital (to risk weighted assets), minimum to be well capitalized under prompt corrective action provisions	643,788	640,563
Common equity Tier 1 capital (to risk weighted assets), minimum to be well capitalized under prompt corrective action provisions	523,078	520,458
Tier 1 capital (to average assets), minimum to be well capitalized under prompt corrective action provisions	$ 482,352	$ 477,620
Capital required to be well capitalized to risk weighted assets	0.1000	0.1000
Tier one risk based capital required to be well capitalized to risk weighted assets	0.0800	0.0800
Common equity tier one risk based capital required to be well capitalized to risk weighted assets	6.50%	6.50%
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	$ 844,972	$ 840,740
Tier 1 capital (to risk weighted assets), minimum capital requirement	684,025	680,599
Common equity Tier 1 capital (to risk weighted assets), minimum capital requirement	563,315	560,493
Tier 1 capital (to average assets), minimum capital requirement	$ 385,881	$ 382,096
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

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
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