Securities Available for Sale and Held to Maturity - Securities with Gross Unrealized Losses, Segregated by Length of Impairment (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	$ 832,097	$ 2,078,165
Estimated Fair Value, 12 Months or More	2,184,478	1,342,186
Estimated Fair Value, Total	3,016,575	3,420,351
Gross Unrealized (Losses), Less than 12 Months	(32,930)	(130,121)
Gross Unrealized (Losses), 12 Months or More	(252,920)	(204,848)
Gross Unrealized (Losses), Total	(285,850)	(334,969)
US Treasury Securities [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	63,262	161,298
Estimated Fair Value, 12 Months or More	323,641	258,087
Estimated Fair Value, Total	386,903	419,385
Gross Unrealized (Losses), Less than 12 Months	(1,138)	(5,655)
Gross Unrealized (Losses), 12 Months or More	(27,801)	(28,974)
Gross Unrealized (Losses), Total	(28,939)	(34,629)
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	66	1,828
Estimated Fair Value, 12 Months or More	7,188	5,938
Estimated Fair Value, Total	7,254	7,766
Gross Unrealized (Losses), Less than 12 Months	(1)	(184)
Gross Unrealized (Losses), 12 Months or More	(490)	(347)
Gross Unrealized (Losses), Total	(491)	(531)
Obligations of States and Political Subdivisions [Member]
Schedule of Available For Sale and Held to Maturity Securities [Line Items]
Estimated Fair Value, Less than 12 Months	1,016	1,017
Estimated Fair Value, 12 Months or More	340	3,664
Estimated Fair Value, Total	1,356	4,681
Gross Unrealized (Losses), Less than 12 Months	(6)	(11)
Gross Unrealized (Losses), 12 Months or More	(1)	(3)
Gross Unrealized (Losses), Total	(7)	(14)
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	2,082	27,223
Estimated Fair Value, 12 Months or More	27,700	3,577
Estimated Fair Value, Total	29,782	30,800
Gross Unrealized (Losses), Less than 12 Months	(112)	(3,270)
Gross Unrealized (Losses), 12 Months or More	(3,095)	(569)
Gross Unrealized (Losses), Total	(3,207)	(3,839)
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	12,872	770,865
Estimated Fair Value, 12 Months or More	1,456,565	1,062,041
Estimated Fair Value, Total	1,469,437	1,832,906
Gross Unrealized (Losses), Less than 12 Months	(692)	(41,807)
Gross Unrealized (Losses), 12 Months or More	(190,074)	(173,898)
Gross Unrealized (Losses), Total	(190,766)	(215,705)
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	51,621	281,964
Estimated Fair Value, 12 Months or More	224,510	7,235
Estimated Fair Value, Total	276,131	289,199
Gross Unrealized (Losses), Less than 12 Months	2,382	(21,452)
Gross Unrealized (Losses), 12 Months or More	15,890	(989)
Gross Unrealized (Losses), Total	18,272	(22,441)
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	701,178	833,970
Estimated Fair Value, 12 Months or More	144,534	1,644
Estimated Fair Value, Total	845,712	835,614
Gross Unrealized (Losses), Less than 12 Months	(28,599)	(57,742)
Gross Unrealized (Losses), 12 Months or More	(15,569)	(68)
Gross Unrealized (Losses), Total	$ (44,168)	$ (57,810)