Securities Available for Sale and Held to Maturity - Securities with Gross Unrealized Losses, Segregated by Length of Impairment (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	$ 48,557	$ 349,545
Gross Unrealized (Losses), Less than 12 Months	(282)	(3,485)
Estimated Fair Value, 12 Months or More	1,202,042	2,758,879
Gross Unrealized (Losses), 12 Months or More	(61,670)	(263,507)
Estimated Fair Value, Total	1,250,599	3,108,424
Gross Unrealized (Losses), Total	(61,952)	(266,992)
US Treasury Securities [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months		29,042
Gross Unrealized (Losses), Less than 12 Months		(26)
Estimated Fair Value, 12 Months or More		372,368
Gross Unrealized (Losses), 12 Months or More		(23,811)
Estimated Fair Value, Total		401,410
Gross Unrealized (Losses), Total		(23,837)
U.S. Government Agency Obligations [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	19,335	0
Gross Unrealized (Losses), Less than 12 Months	(159)	0
Estimated Fair Value, 12 Months or More	0	5,791
Gross Unrealized (Losses), 12 Months or More	0	(416)
Estimated Fair Value, Total	19,335	5,791
Gross Unrealized (Losses), Total	(159)	(416)
Residential Mortgage Pass-Through Securities Guaranteed by GNMA [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	11,089	9,381
Gross Unrealized (Losses), Less than 12 Months	(51)	(172)
Estimated Fair Value, 12 Months or More	29,760	25,967
Gross Unrealized (Losses), 12 Months or More	(2,360)	(2,938)
Estimated Fair Value, Total	40,849	35,348
Gross Unrealized (Losses), Total	(2,411)	(3,110)
Residential Mortgage Pass-Through Securities Issued by FNMA and FHLMC [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	18,133	309,466
Gross Unrealized (Losses), Less than 12 Months	(72)	(3,274)
Estimated Fair Value, 12 Months or More	254,346	1,311,865
Gross Unrealized (Losses), 12 Months or More	(25,364)	(176,421)
Estimated Fair Value, Total	272,479	1,621,331
Gross Unrealized (Losses), Total	(25,436)	(179,695)
Other Residential Mortgage-Backed Securities Issued or Guaranteed by FNMA, FHLMC or GNMA [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	0	0
Gross Unrealized (Losses), Less than 12 Months	0	0
Estimated Fair Value, 12 Months or More	125,169	230,368
Gross Unrealized (Losses), 12 Months or More	(6,179)	(16,115)
Estimated Fair Value, Total	125,169	230,368
Gross Unrealized (Losses), Total	(6,179)	(16,115)
Commercial Mortgage-Backed Securities Issued or Guaranteed by FNMA, FHLMC or GNMA [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	0	1,656
Gross Unrealized (Losses), Less than 12 Months	0	(13)
Estimated Fair Value, 12 Months or More	792,767	812,520
Gross Unrealized (Losses), 12 Months or More	(27,767)	(43,806)
Estimated Fair Value, Total	792,767	814,176
Gross Unrealized (Losses), Total	$ (27,767)	$ (43,819)