Securities - Amortized Cost and Fair Value of Securities Available for Sale (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Amortized cost and fair value of securities available for sale
Amortized Cost	$ 2,754,317	$ 2,400,956
Gross Unrealized Gains	1,123	16,120
Gross Unrealized Losses	(227,187)	(31,024)
Fair Value	2,528,253	2,386,052
Obligations of other U.S. Government agencies and corporations
Amortized cost and fair value of securities available for sale
Amortized Cost	145,000
Gross Unrealized Gains	125
Gross Unrealized Losses	(643)
Fair Value	144,482
U.S. Treasury securities
Amortized cost and fair value of securities available for sale
Amortized Cost		3,007
Gross Unrealized Gains		3
Gross Unrealized Losses		0
Fair Value		3,010
Obligations of states and political subdivisions
Amortized cost and fair value of securities available for sale
Amortized Cost	158,609	153,847
Gross Unrealized Gains	533	5,532
Gross Unrealized Losses	(9,390)	(269)
Fair Value	149,752	159,110
Other debt securities
Amortized cost and fair value of securities available for sale
Amortized Cost	123,068	36,515
Gross Unrealized Gains	60	1,097
Gross Unrealized Losses	(4,198)	(148)
Fair Value	118,930	37,464
Government agency mortgage backed securities \| Residential mortgage backed securities:
Amortized cost and fair value of securities available for sale
Amortized Cost	993,319	967,497
Gross Unrealized Gains	334	7,854
Gross Unrealized Losses	(74,237)	(6,816)
Fair Value	919,416	968,535
Government agency mortgage backed securities \| Commercial mortgage backed securities:
Amortized cost and fair value of securities available for sale
Amortized Cost	11,241	14,717
Gross Unrealized Gains	0	365
Gross Unrealized Losses	(568)	(1)
Fair Value	10,673	15,081
Government agency collateralized mortgage obligations \| Residential mortgage backed securities:
Amortized cost and fair value of securities available for sale
Amortized Cost	1,099,846	1,008,514
Gross Unrealized Gains	3	457
Gross Unrealized Losses	(119,929)	(20,371)
Fair Value	979,920	988,600
Government agency collateralized mortgage obligations \| Commercial mortgage backed securities:
Amortized cost and fair value of securities available for sale
Amortized Cost	223,234	216,859
Gross Unrealized Gains	68	812
Gross Unrealized Losses	(18,222)	(3,419)
Fair Value	$ 205,080	$ 214,252

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).

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