Investment Securities - Schedule of AFS Debt Securities in an Unrealized Loss Position (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Fair Value	$ 83,812	$ 238,023
Less Than 12 Months, Gross Unrealized Losses	(67)	(4,044)
12 Months or Longer, Fair Value	2,183,212	2,089,545
12 Months or Longer, Gross Unrealized Losses	(219,619)	(281,739)
Total Fair Value	2,267,024	2,327,568
Total Gross Unrealized Losses	(219,686)	(285,783)
Debt Securities Issued by the U.S. Treasury and Government Agencies
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Fair Value	32,603	7,171
Less Than 12 Months, Gross Unrealized Losses	(66)	(16)
12 Months or Longer, Fair Value	157,416	155,341
12 Months or Longer, Gross Unrealized Losses	(7,156)	(11,080)
Total Fair Value	190,019	162,512
Total Gross Unrealized Losses	(7,222)	(11,096)
Debt Securities Issued by States and Political Subdivisions
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Fair Value		237
Less Than 12 Months, Gross Unrealized Losses		(2)
12 Months or Longer, Fair Value	65,810	63,509
12 Months or Longer, Gross Unrealized Losses	(7,297)	(9,609)
Total Fair Value	65,810	63,746
Total Gross Unrealized Losses	(7,297)	(9,611)
Debt Securities Issued by Government-Sponsored Enterprises
Schedule Of Available For Sale Securities [Line Items]
12 Months or Longer, Fair Value	1,464	1,476
12 Months or Longer, Gross Unrealized Losses	(42)	(80)
Total Fair Value	1,464	1,476
Total Gross Unrealized Losses	(42)	(80)
Debt Securities Issued by Corporations
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Fair Value		220,987
Less Than 12 Months, Gross Unrealized Losses		(4,013)
12 Months or Longer, Fair Value	598,286	411,573
12 Months or Longer, Gross Unrealized Losses	(30,623)	(44,430)
Total Fair Value	598,286	632,560
Total Gross Unrealized Losses	(30,623)	(48,443)
Residential - Government Agencies
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Fair Value	2,211	9,628
Less Than 12 Months, Gross Unrealized Losses	(1)	(13)
12 Months or Longer, Fair Value	565,187	613,926
12 Months or Longer, Gross Unrealized Losses	(68,652)	(84,772)
Total Fair Value	567,398	623,554
Total Gross Unrealized Losses	(68,653)	(84,785)
Residential - U.S. Government-Sponsored Enterprises
Schedule Of Available For Sale Securities [Line Items]
12 Months or Longer, Fair Value	662,402	708,797
12 Months or Longer, Gross Unrealized Losses	(85,799)	(109,176)
Total Fair Value	662,402	708,797
Total Gross Unrealized Losses	(85,799)	(109,176)
Commercial - Government Agencies or Sponsored Agencies
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Fair Value	48,998
12 Months or Longer, Fair Value	132,647	134,923
12 Months or Longer, Gross Unrealized Losses	(20,050)	(22,592)
Total Fair Value	181,645	134,923
Total Gross Unrealized Losses	(20,050)	(22,592)
Mortgage-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Fair Value	51,209	9,628
Less Than 12 Months, Gross Unrealized Losses	(1)	(13)
12 Months or Longer, Fair Value	1,360,236	1,457,646
12 Months or Longer, Gross Unrealized Losses	(174,501)	(216,540)
Total Fair Value	1,411,445	1,467,274
Total Gross Unrealized Losses	$ (174,502)	$ (216,553)

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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