Short-term Borrowings - Interest Expense on Short-Term Borrowings (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Interest On Short Term Borrowings [Line Items]
Total interest on short-term borrowings	$ 8,298	$ 10,741	$ 8,799
Federal funds purchased
Interest On Short Term Borrowings [Line Items]
Total interest on short-term borrowings	204	180	77
Borrowings from FHLB
Interest On Short Term Borrowings [Line Items]
Total interest on short-term borrowings	7,313	9,929	8,360
Securities sold under agreements to repurchase
Interest On Short Term Borrowings [Line Items]
Total interest on short-term borrowings	$ 781	$ 632	$ 362