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Borrowings - FHLB Advances - Additional Information (Details)	12 Months Ended
	Dec. 31, 2025 USD ($) Loan	Dec. 31, 2024 USD ($) Loan	Dec. 31, 2023 USD ($)
Debt Instrument [Line Items]
Weighted-average cost related to FHLB advances (in hundredths)	3.64%	4.60%
Weighted average remaining maturity	2 days	8 days
Dallas [Member] | Federal Home Loan Bank Advances
Debt Instrument [Line Items]
Number of outstanding short-term FHLB advances | Loan	2	2
Short-term FHLB advances	$ 225,000,000	$ 200,000,000
Interest expense, long-term borrowings	0	0	$ 0
Long-term FHLB advances	0	0
Additional debt instrument borrowing capacity	1,962,000,000	4,292,000,000
Dallas [Member] | Short Term FhlbAdvances1 [Member] | Federal Home Loan Bank Advances
Debt Instrument [Line Items]
Short-term FHLB advances	$ 150,000,000
Interest rate (in hundredths)	3.62%
Dallas [Member] | Short Term FhlbAdvances2 [Member] | Federal Home Loan Bank Advances
Debt Instrument [Line Items]
Short-term FHLB advances	$ 75,000,000
Interest rate (in hundredths)	3.67%
Dallas [Member] | Fair Market Value Adjustment [Member] | Federal Home Loan Bank Advances
Debt Instrument [Line Items]
Interest expense, short-term borrowings	$ 9,500,000	$ 16,800,000	$ 49,900,000

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