Securities - Amortized Cost and Fair Value of Securities Available for Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Amortized cost and fair value of securities available for sale
Amortized Cost	$ 1,688,251	$ 1,735,000
Gross Unrealized Gains	469	241
Gross Unrealized Losses	(180,813)	(201,299)
Fair Value	1,507,907	1,533,942
Obligations of other U.S. Government agencies and corporations
Amortized cost and fair value of securities available for sale
Amortized Cost	170,000	170,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(4,110)	(5,340)
Fair Value	165,890	164,660
Obligations of states and political subdivisions
Amortized cost and fair value of securities available for sale
Amortized Cost	149,646	154,066
Gross Unrealized Gains	377	204
Gross Unrealized Losses	(6,866)	(9,368)
Fair Value	143,157	144,902
Residential mortgage backed securities: \| Government agency mortgage backed securities
Amortized cost and fair value of securities available for sale
Amortized Cost	487,834	508,415
Gross Unrealized Gains	77	37
Gross Unrealized Losses	(45,812)	(52,036)
Fair Value	442,099	456,416
Residential mortgage backed securities: \| Government agency collateralized mortgage obligations
Amortized cost and fair value of securities available for sale
Amortized Cost	589,560	605,033
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(95,044)	(103,864)
Fair Value	494,516	501,169
Commercial mortgage backed securities: \| Government agency mortgage backed securities
Amortized cost and fair value of securities available for sale
Amortized Cost	11,128	11,166
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(900)	(1,053)
Fair Value	10,228	10,113
Commercial mortgage backed securities: \| Government agency collateralized mortgage obligations
Amortized cost and fair value of securities available for sale
Amortized Cost	207,032	211,435
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(24,236)	(25,589)
Fair Value	182,796	185,846
Other debt securities
Amortized cost and fair value of securities available for sale
Amortized Cost	73,051	74,885
Gross Unrealized Gains	15	0
Gross Unrealized Losses	(3,845)	(4,049)
Fair Value	$ 69,221	$ 70,836

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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