Fair Value Measurements (Details 2) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Fair value measurements
Investment securities available-for-sale	$ 1,605,242	$ 1,775,128
Assets:
Mortgages held for sale	3,118	3,914
U.S. Treasury and Federal agencies securities
Fair value measurements
Investment securities available-for-sale	946,962	998,598
U.S. States and political subdivisions securities
Fair value measurements
Investment securities available-for-sale	96,984	122,762
Mortgage-backed securities - Federal agencies
Fair value measurements
Investment securities available-for-sale	552,463	637,058
Corporate debt securities
Fair value measurements
Investment securities available-for-sale	8,251	16,131
Foreign government and other securities
Fair value measurements
Investment securities available-for-sale	582	579
Total
Fair value measurements
Investment securities available-for-sale	1,605,242	1,775,128
Assets:
Mortgages held for sale	3,118	3,914
Level 1
Fair value measurements
Investment securities available-for-sale	539,836	573,679
Assets:
Mortgages held for sale	0	0
Level 2
Fair value measurements
Investment securities available-for-sale	1,061,268	1,199,985
Assets:
Mortgages held for sale	3,118	3,914
Level 3
Fair value measurements
Investment securities available-for-sale	4,138	1,464
Assets:
Mortgages held for sale	0	0
Recurring basis \| Total
Fair value measurements
Investment securities available-for-sale	1,605,242	1,775,128
Assets:
Mortgages held for sale	3,118	3,914
Total	1,635,381	1,803,880
Liabilities:
Total	27,531	25,307
Recurring basis \| Total \| Interest rate swap contracts
Assets:
Accrued income and other assets	27,021	24,838
Liabilities:
Accrued expenses and other liabilities	27,531	25,307
Recurring basis \| Total \| U.S. Treasury and Federal agencies securities
Fair value measurements
Investment securities available-for-sale	946,962	998,598
Recurring basis \| Total \| U.S. States and political subdivisions securities
Fair value measurements
Investment securities available-for-sale	96,984	122,762
Recurring basis \| Total \| Mortgage-backed securities - Federal agencies
Fair value measurements
Investment securities available-for-sale	552,463	637,058
Recurring basis \| Total \| Corporate debt securities
Fair value measurements
Investment securities available-for-sale	8,251	16,131
Recurring basis \| Total \| Foreign government and other securities
Fair value measurements
Investment securities available-for-sale	582	579
Recurring basis \| Level 1
Fair value measurements
Investment securities available-for-sale	539,836	573,679
Assets:
Mortgages held for sale	0	0
Total	539,836	573,679
Liabilities:
Total	0	0
Recurring basis \| Level 1 \| Interest rate swap contracts
Assets:
Accrued income and other assets	0	0
Liabilities:
Accrued expenses and other liabilities	0	0
Recurring basis \| Level 1 \| U.S. Treasury and Federal agencies securities
Fair value measurements
Investment securities available-for-sale	539,836	573,679
Recurring basis \| Level 1 \| U.S. States and political subdivisions securities
Fair value measurements
Investment securities available-for-sale	0	0
Recurring basis \| Level 1 \| Mortgage-backed securities - Federal agencies
Fair value measurements
Investment securities available-for-sale	0	0
Recurring basis \| Level 1 \| Corporate debt securities
Fair value measurements
Investment securities available-for-sale	0	0
Recurring basis \| Level 1 \| Foreign government and other securities
Fair value measurements
Investment securities available-for-sale	0	0
Recurring basis \| Level 2
Fair value measurements
Investment securities available-for-sale	1,061,268	1,199,985
Assets:
Mortgages held for sale	3,118	3,914
Total	1,091,407	1,228,737
Liabilities:
Total	27,531	25,307
Recurring basis \| Level 2 \| Interest rate swap contracts
Assets:
Accrued income and other assets	27,021	24,838
Liabilities:
Accrued expenses and other liabilities	27,531	25,307
Recurring basis \| Level 2 \| U.S. Treasury and Federal agencies securities
Fair value measurements
Investment securities available-for-sale	407,126	424,919
Recurring basis \| Level 2 \| U.S. States and political subdivisions securities
Fair value measurements
Investment securities available-for-sale	92,846	121,298
Recurring basis \| Level 2 \| Mortgage-backed securities - Federal agencies
Fair value measurements
Investment securities available-for-sale	552,463	637,058
Recurring basis \| Level 2 \| Corporate debt securities
Fair value measurements
Investment securities available-for-sale	8,251	16,131
Recurring basis \| Level 2 \| Foreign government and other securities
Fair value measurements
Investment securities available-for-sale	582	579
Recurring basis \| Level 3
Fair value measurements
Investment securities available-for-sale	4,138	1,464
Assets:
Mortgages held for sale	0	0
Total	4,138	1,464
Liabilities:
Total	0	0
Recurring basis \| Level 3 \| Interest rate swap contracts
Assets:
Accrued income and other assets	0	0
Liabilities:
Accrued expenses and other liabilities	0	0
Recurring basis \| Level 3 \| U.S. Treasury and Federal agencies securities
Fair value measurements
Investment securities available-for-sale	0	0
Recurring basis \| Level 3 \| U.S. States and political subdivisions securities
Fair value measurements
Investment securities available-for-sale	4,138	1,464
Recurring basis \| Level 3 \| Mortgage-backed securities - Federal agencies
Fair value measurements
Investment securities available-for-sale	0	0
Recurring basis \| Level 3 \| Corporate debt securities
Fair value measurements
Investment securities available-for-sale	0	0
Recurring basis \| Level 3 \| Foreign government and other securities
Fair value measurements
Investment securities available-for-sale	$ 0	$ 0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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