Investment Securities - Schedule of AFS Debt Securities in an Unrealized Loss Position (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Fair Value	$ 2,958,470	$ 2,808,862
Less Than 12 Months, Gross Unrealized Losses	(186,011)	(56,121)
12 Months or Longer, Fair Value	1,036,280	317,559
12 Months or Longer, Gross Unrealized Losses	(106,523)	(10,167)
Total Fair Value	3,994,750	3,126,421
Total Gross Unrealized Losses	(292,534)	(66,288)
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	155,571	51,455
Less Than 12 Months, Gross Unrealized Losses	(7,610)	(195)
12 Months or Longer, Fair Value	9,150	9,995
12 Months or Longer, Gross Unrealized Losses	(83)	(89)
Total Fair Value	164,721	61,450
Total Gross Unrealized Losses	(7,693)	(284)
Debt Securities Issued by States and Political Subdivisions
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Fair Value	68,458	643
Less Than 12 Months, Gross Unrealized Losses	(5,062)	(5)
Total Fair Value	68,458	643
Total Gross Unrealized Losses	(5,062)	(5)
Debt Securities Issued by Government-Sponsored Enterprises
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Fair Value	1,654	814
Less Than 12 Months, Gross Unrealized Losses	(54)	(10)
12 Months or Longer, Fair Value	46	49
12 Months or Longer, Gross Unrealized Losses	(3)	(1)
Total Fair Value	1,700	863
Total Gross Unrealized Losses	(57)	(11)
Debt Securities Issued by Corporations
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Fair Value	295,711	249,629
Less Than 12 Months, Gross Unrealized Losses	(19,798)	(2,846)
12 Months or Longer, Fair Value	86,176	64,029
12 Months or Longer, Gross Unrealized Losses	(3,824)	(970)
Total Fair Value	381,887	313,658
Total Gross Unrealized Losses	(23,622)	(3,816)
Residential - Government Agencies
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Fair Value	1,053,590	810,157
Less Than 12 Months, Gross Unrealized Losses	(63,144)	(17,131)
12 Months or Longer, Fair Value	134,437	41,471
12 Months or Longer, Gross Unrealized Losses	(14,891)	(1,635)
Total Fair Value	1,188,027	851,628
Total Gross Unrealized Losses	(78,035)	(18,766)
Residential - U.S. Government-Sponsored Enterprises
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Fair Value	1,228,427	1,670,500
Less Than 12 Months, Gross Unrealized Losses	(85,268)	(35,711)
12 Months or Longer, Fair Value	786,229	180,205
12 Months or Longer, Gross Unrealized Losses	(85,665)	(6,536)
Total Fair Value	2,014,656	1,850,705
Total Gross Unrealized Losses	(170,933)	(42,247)
Commercial - Government Agencies or Sponsored Agencies
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Fair Value	155,059	25,664
Less Than 12 Months, Gross Unrealized Losses	(5,075)	(223)
12 Months or Longer, Fair Value	20,242	21,810
12 Months or Longer, Gross Unrealized Losses	(2,057)	(936)
Total Fair Value	175,301	47,474
Total Gross Unrealized Losses	(7,132)	(1,159)
Mortgage-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Less Than 12 Months, Fair Value	2,437,076	2,506,321
Less Than 12 Months, Gross Unrealized Losses	(153,487)	(53,065)
12 Months or Longer, Fair Value	940,908	243,486
12 Months or Longer, Gross Unrealized Losses	(102,613)	(9,107)
Total Fair Value	3,377,984	2,749,807
Total Gross Unrealized Losses	$ (256,100)	$ (62,172)