Loans and Allowance for Credit Losses - Troubled Debt Restructurings Identified During Period (Detail) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($) Contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract				2
Total Pre-Modification Outstanding Recorded Investment				$ 69
Post- Modification Outstanding Recorded Investment	$ 207		$ 632	68
Troubled Debt Restructuring [Policy Text Block]				0
Financing Receivable, Troubled Debt Restructuring, Subsequent Default		$ 0	0	$ 0
Residential real estate [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract				2
Total Pre-Modification Outstanding Recorded Investment				$ 69
Post- Modification Outstanding Recorded Investment	207		632	68
Troubled Debt Restructuring [Policy Text Block]				$ 0
Senior Lien | Residential real estate [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | Contract				2
Total Pre-Modification Outstanding Recorded Investment				$ 69
Post- Modification Outstanding Recorded Investment	207		632	68
Troubled Debt Restructuring [Policy Text Block]				0
Extended Maturity [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Pre-Modification Outstanding Recorded Investment				0
Post- Modification Outstanding Recorded Investment	144		305
Extended Maturity [Member] | Residential real estate [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Pre-Modification Outstanding Recorded Investment				0
Post- Modification Outstanding Recorded Investment	144		305
Extended Maturity [Member] | Senior Lien | Residential real estate [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Pre-Modification Outstanding Recorded Investment				0
Post- Modification Outstanding Recorded Investment	144		305
Contractual Interest Rate Reduction [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Pre-Modification Outstanding Recorded Investment				10
Post- Modification Outstanding Recorded Investment	0		22
Contractual Interest Rate Reduction [Member] | Residential real estate [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Pre-Modification Outstanding Recorded Investment				10
Post- Modification Outstanding Recorded Investment	0		22
Contractual Interest Rate Reduction [Member] | Senior Lien | Residential real estate [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Pre-Modification Outstanding Recorded Investment				10
Post- Modification Outstanding Recorded Investment	$ 0		$ 22
Contractual Payment Modification [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Pre-Modification Outstanding Recorded Investment				59
Contractual Payment Modification [Member] | Residential real estate [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Pre-Modification Outstanding Recorded Investment				59
Contractual Payment Modification [Member] | Senior Lien | Residential real estate [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total Pre-Modification Outstanding Recorded Investment				$ 59