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	Mar. 31, 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	108	37
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 1,045,389	$ 170,971
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(28,260)	(1,016)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	439	5,424
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(11)	(33)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	1,045,828	176,395
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (28,271)	$ (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	13	5
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 106,908	$ 30,639
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(3,270)	(137)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	106,908	30,639
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (3,270)	$ (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	8	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 13,689	$ 210
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(292)	(85)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	13,689	210
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (292)	$ (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	59	8
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 781,666	$ 45,253
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(19,074)	(198)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	439	472
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses	(11)	(7)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	782,105	45,725
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (19,085)	$ (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	4	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 28,484	$ 3,963
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(761)	(5)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	28,484	3,963
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (761)	$ (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	20	8
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 106,172	$ 55,554
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(4,795)	(390)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	106,172	55,554
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (4,795)	$ (390)
Corporate Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	4	6
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 8,470	$ 10,916
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(68)	(102)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	8,470	10,916
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (68)	$ (102)
Asset-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security		6
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value		$ 24,436
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses		(99)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value		4,952
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses		(26)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value		29,388
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses		$ (125)