Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 04, 2019
Goodwill And Intangible Assets [Line Items]
Goodwill		$ 156,277	$ 156,277
Core deposit intangible amortization		1,025	1,182	$ 594
Highlands Bancorp, Inc.
Goodwill And Intangible Assets [Line Items]
Goodwill					$ 19,844
Goodwill acquired	$ 19,800
Core Deposits
Goodwill And Intangible Assets [Line Items]
Core deposit intangible		$ 3,300	$ 4,300
Core Deposits | Highlands Bancorp, Inc.
Goodwill And Intangible Assets [Line Items]
Intangible assets acquired	$ 3,700