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, 2020 USD ($) Security	Dec. 31, 2019 USD ($) Security
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	50	99
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 205,062	$ 343,722
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(8,194)	(2,377)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value		257,869
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses		(2,328)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	205,062	601,591
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (8,194)	$ (4,705)
U.S. Government Agencies
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security		8
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value		$ 49,318
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses		(662)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value		20,283
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses		(92)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value		69,601
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses		$ (754)
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	7
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 5,951	$ 13,309
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(107)	(45)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value		1,419
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses		(4)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	5,951	14,728
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (107)	$ (49)
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	1	50
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 564	$ 132,703
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(12)	(666)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value		193,363
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses		(1,688)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	564	326,066
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (12)	$ (2,354)
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	10	9
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 52,821	$ 36,902
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(959)	(206)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value		10,126
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses		(66)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	52,821	47,028
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (959)	$ (272)
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	6	13
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 53,000	$ 67,649
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(579)	(563)
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value		32,678
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Unrealized Losses		(478)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	53,000	100,327
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (579)	$ (1,041)
Non-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	5
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 30,543
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(521)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	30,543
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (521)
Corporate Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	12	4
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 22,426	$ 6,103
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(1,257)	(37)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	22,426	6,103
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (1,257)	$ (37)
Asset-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Number of Securities | Security	9	8
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 39,757	$ 37,738
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Unrealized Losses	(4,759)	(198)
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Fair Value	39,757	37,738
Available-for-sale Securities, Continuous Unrealized Loss Position, Total Unrealized Losses	$ (4,759)	$ (198)