Loans Held for Investment and Allowance for Loan Losses - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual, past due 90 days or more and still accruing, restructured loans and foreclosed assets	$ 37,204,000	$ 24,389,000	$ 35,096,000
Additional funds advanced in connection with impaired loans	0
Loans held by subsidiaries subject to blanket liens	5,095,506,000
Available line of credit	1,984,900,000
line of Credit	0
Undisbursed commitments	781,500,000
Reserve for unfunded commitments (Other liabilities)	7,455,000	10,397,000	7,903,000
Total Loans	7,229,410,000	6,576,215,000	$ 7,148,791,000
Provision for Loan and Lease Losses	1,256,000	4,707,000
Unfunded Loan Commitment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Loan and Lease Losses	448,000	1,926,000
Reversal of Provision for credit losses	$ 808,000	$ 2,781,000