Securities - Summary of Gross Unrealized Losses and Fair Values, Aggregated by Investment Category and Length of Individual Securities Continuous Unrealized Loss Position Available-for-sale (Details) $ in Thousands	Sep. 30, 2021 USD ($) Security	Dec. 31, 2020 USD ($) Security
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	97	37
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 822,458	$ 170,971
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(17,405)	(1,016)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	48,269	5,424
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(1,496)	(33)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	870,727	176,395
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (18,901)	$ (1,049)
U.S. Government Agencies
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	10	5
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 74,687	$ 30,639
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(1,506)	(137)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	9,641	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(359)	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	84,328	30,639
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (1,865)	$ (137)
Obligations of States, Municipalities, and Political Subdivisions
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	7	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 8,097	$ 210
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(164)	(85)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	8,097	210
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (164)	$ (85)
Agency, Residential Mortgage-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	51	8
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 620,325	$ 45,253
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(12,626)	(198)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	11,805	472
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(360)	(7)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	632,130	45,725
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (12,986)	$ (205)
Non-Agency, Residential Mortgage-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	5	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 34,310	$ 3,963
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(722)	(5)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	34,310	3,963
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (722)	$ (5)
Agency, Commercial Mortgage-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	21	8
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 75,001	$ 55,554
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(2,369)	(390)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	26,823	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(777)	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	101,824	55,554
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (3,146)	$ (390)
Corporate Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	2	6
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 5,041	$ 10,916
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(17)	(102)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	5,041	10,916
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (17)	$ (102)
Asset-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	1	6
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 4,997	$ 24,436
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(1)	(99)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	0	4,952
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	0	(26)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	4,997	29,388
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (1)	$ (125)