Loans and Allowance for Credit Losses on Loans - Loans Held for Investment by Portfolio Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025	Sep. 30, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	$ 24,082,990	$ 24,040,202
Allowance for credit losses on loans	(270,333)	(270,557)	$ (274,026)	$ (271,709)
Loans held for investment, net	23,812,657	23,769,645
Loans held for sale	28,676	4,361
Interest receivable	106,900	107,300
Unearned income (net of direct origination costs)	(108,000)	(106,800)
Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	13,428,328	12,163,545
Allowance for credit losses on loans	(235,826)	(202,029)	(197,537)	(198,423)
Mortgage finance
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	5,441,689	6,064,019
Allowance for credit losses on loans	(3,384)	(6,221)	(8,699)	(2,755)
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	4,786,513	5,378,712
Allowance for credit losses on loans	(29,359)	(60,559)	(66,001)	(68,825)
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total	426,460	433,926
Allowance for credit losses on loans	$ (1,764)	$ (1,748)	$ (1,789)	$ (1,706)

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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