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Allowance for Credit Losses (Held-to-Maturity Debt Securities by Credit Quality Indication) (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
Amortized Cost	$ 3,390,152	$ 2,942,363	$ 2,736,805
Less: Allowance for credit losses	(310)	(78)	(83)
Held-to-maturity securities, net of allowance for credit losses	3,389,842	2,942,285	2,736,722
U.S. government agencies
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2022	135,000
2021	147,799
2020	25,000
2019	4,000
2018	0
Prior	2,819
Amortized Cost	314,618	180,192	176,143
U.S. government agencies \| 1-4 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2022	135,000
2021	147,799
2020	25,000
2019	4,000
2018	0
Prior	2,819
Amortized Cost	314,618
U.S. government agencies \| 5-7 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Amortized Cost	0
U.S. government agencies \| 8-10 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Amortized Cost	0
Municipal
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2022	0
2021	7,023
2020	275
2019	160
2018	7,423
Prior	165,423
Amortized Cost	180,304	$ 187,486	$ 190,662
Municipal \| 1-4 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2022	0
2021	7,023
2020	275
2019	160
2018	7,423
Prior	165,423
Amortized Cost	180,304
Municipal \| 5-7 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Amortized Cost	0
Municipal \| 8-10 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Amortized Cost	0
Mortgage-backed securities
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2022	369,719
2021	2,477,108
2020	0
2019	0
2018	0
Prior	0
Amortized Cost	2,846,827
Mortgage-backed securities \| 1-4 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2022	369,719
2021	2,477,108
2020	0
2019	0
2018	0
Prior	0
Amortized Cost	2,846,827
Mortgage-backed securities \| 5-7 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Amortized Cost	0
Mortgage-backed securities \| 8-10 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Amortized Cost	0
Corporate notes
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2022	4,962
2021	0
2020	6,010
2019	7,334
2018	3,203
Prior	26,894
Amortized Cost	48,403
Corporate notes \| 1-4 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2022	4,962
2021	0
2020	6,010
2019	7,334
2018	3,203
Prior	26,894
Amortized Cost	48,403
Corporate notes \| 5-7 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Amortized Cost	0
Corporate notes \| 8-10 internal grade
Debt Securities, Held-to-maturity, Credit Quality Indicator [Line Items]
2022	0
2021	0
2020	0
2019	0
2018	0
Prior	0
Amortized Cost	$ 0