Loans - Schedule of Recorded Investment in Nonaccrual and Loans Past Due Over 90 Days on Accrual by Class of Loans (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	$ 27,035	$ 5,488
Loans Past Due Over 90 Days	654	208
Construction loans | Construction loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	30	2,298
Loans Past Due Over 90 Days	0	0
Residential Real Estate | Closed-end 1-4 family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	954	1,273
Loans Past Due Over 90 Days	0	0
Residential Real Estate | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	1,523	1,917
Loans Past Due Over 90 Days	0	0
Commercial and Industrial | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Nonaccrual	24,528	0
Loans Past Due Over 90 Days	$ 654	$ 208