Loans Held-for-Investment and Allowance for Credit Losses - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual, past due 90 days or more and still accruing, restructured loans and foreclosed assets	$ 61,688,000	$ 37,204,000	$ 63,096,000
Additional funds advanced in connection with impaired loans	0
Loans held by subsidiaries subject to blanket liens	5,577,155,000
Available line of credit	2,118,666,000
Undisbursed commitments	810,000,000
Reserve for unfunded commitments (Other liabilities)	9,214,000	7,455,000	$ 8,677,000
Provision for loan losses	2,991,000	1,256,000
Unfunded Loan Commitment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for loan losses	3,528,000	808,000
Reversal of Provision for credit losses	$ 537,000	$ 448,000