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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, 2024	Dec. 31, 2023	Sep. 30, 2023
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Amortized Cost	$ 3,677,899	$ 3,857,263	$ 3,909,531
Less: Allowance for credit losses	(479)	(347)	(381)
Held-to-maturity securities, net of allowance for credit losses	3,677,420	3,856,916	3,909,150
U.S. government agencies
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2024	0
2023	0
2022	135,000
2021	147,818
2020	25,000
Prior	6,760
Amortized Cost	314,578	336,468	339,598
U.S. government agencies \| 1-4 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2024	0
2023	0
2022	135,000
2021	147,818
2020	25,000
Prior	6,760
Amortized Cost	314,578
U.S. government agencies \| 5-7 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2024
2023
2022
2021
2020
Prior
Amortized Cost	0
U.S. government agencies \| 8-10 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2024
2023
2022
2021
2020
Prior
Amortized Cost	0
Municipal
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2024	0
2023	4,176
2022	1,034
2021	6,839
2020	258
Prior	152,834
Amortized Cost	165,141	$ 172,933	$ 176,262
Municipal \| 1-4 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2024	0
2023	4,176
2022	1,034
2021	6,839
2020	258
Prior	150,481
Amortized Cost	162,788
Municipal \| 5-7 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2024	0
2023	0
2022	0
2021	0
2020	0
Prior	2,353
Amortized Cost	2,353
Municipal \| 8-10 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2024
2023
2022
2021
2020
Prior
Amortized Cost	0
Mortgage-backed securities
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2024	0
2023	352,905
2022	544,887
2021	2,243,363
2020	0
Prior	0
Amortized Cost	3,141,155
Mortgage-backed securities \| 1-4 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2024	0
2023	352,905
2022	544,887
2021	2,243,363
2020	0
Prior	0
Amortized Cost	3,141,155
Mortgage-backed securities \| 5-7 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2024
2023
2022
2021
2020
Prior
Amortized Cost	0
Mortgage-backed securities \| 8-10 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2024
2023
2022
2021
2020
Prior
Amortized Cost	0
Corporate notes
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2024	0
2023	0
2022	14,968
2021	0
2020	6,005
Prior	36,052
Amortized Cost	57,025
Corporate notes \| 1-4 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2024	0
2023	0
2022	14,968
2021	0
2020	6,005
Prior	36,052
Amortized Cost	57,025
Corporate notes \| 5-7 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2024
2023
2022
2021
2020
Prior
Amortized Cost	0
Corporate notes \| 8-10 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2024
2023
2022
2021
2020
Prior
Amortized Cost	$ 0