Loans Held for Investment and Allowance for Credit Losses on Loans - Schedule of Portfolio Segments Weighted Average Life, and Measures the Allowance for Credit Losses (Detail) - ASC 326 [Member]	12 Months Ended
	Dec. 31, 2023
Real Estate [Member] | Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan Segment, Life (in years)	9 years
Real Estate [Member] | Commercial Real Estate Non-Owner Occupied [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan Segment, Life (in years)	6 years
Real Estate [Member] | Construction and Development Less than 60 Months [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan Segment, Life (in years)	3 years
Real Estate [Member] | Construction Residential Real Estate Less than 60 Months [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan Segment, Life (in years)	2 years
Real Estate [Member] | Residential Real Estate First Lien [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan Segment, Life (in years)	15 years
Real Estate [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan Segment, Life (in years)	8 years
Real Estate [Member] | Agriculture [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan Segment, Life (in years)	9 years
Commercial Non-real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan Segment, Life (in years)	4 years
Consumer Non-real Estate [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan Segment, Life (in years)	4 years
Oil and Gas [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loan Segment, Life (in years)	2 years