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Allowance for Credit Losses - Schedule of Held-to-Maturity Debt Securities by Credit Quality Indicator (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024	Sep. 30, 2024
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Amortized Cost	$ 3,438,801	$ 3,613,720	$ 3,677,899
Less: Allowance for credit losses	(395)	(457)	(479)
Held-to-maturity securities, net of allowance for credit losses	3,438,406	3,613,263	3,677,420
U.S. government agencies
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	135,000
2021	147,827
Prior	30,713
Amortized Cost	313,540	313,539	314,578
U.S. government agencies \| 1-4 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	135,000
2021	147,827
Prior	30,713
Amortized Cost	313,540
U.S. government agencies \| 5-7 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	0
2021	0
Prior	0
Amortized Cost	0
U.S. government agencies \| 8-10 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	0
2021	0
Prior	0
Amortized Cost	0
Municipal
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	4,092
2022	1,028
2021	6,742
Prior	143,908
Amortized Cost	155,770	$ 161,016	$ 165,141
Municipal \| 1-4 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	4,092
2022	1,028
2021	6,742
Prior	141,784
Amortized Cost	153,646
Municipal \| 5-7 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	0
2021	0
Prior	2,124
Amortized Cost	2,124
Municipal \| 8-10 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	0
2021	0
Prior	0
Amortized Cost	0
Mortgage-backed securities
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	296,804
2022	496,580
2021	2,125,596
Prior	0
Amortized Cost	2,918,980
Mortgage-backed securities \| 1-4 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	296,804
2022	496,580
2021	2,125,596
Prior	0
Amortized Cost	2,918,980
Mortgage-backed securities \| 5-7 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	0
2021	0
Prior	0
Amortized Cost	0
Mortgage-backed securities \| 8-10 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	0
2021	0
Prior	0
Amortized Cost	0
Corporate notes
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	14,972
2021	0
Prior	35,539
Amortized Cost	50,511
Corporate notes \| 1-4 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	14,972
2021	0
Prior	35,539
Amortized Cost	50,511
Corporate notes \| 5-7 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	0
2021	0
Prior	0
Amortized Cost	0
Corporate notes \| 8-10 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2025	0
2024	0
2023	0
2022	0
2021	0
Prior	0
Amortized Cost	$ 0