SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE - Narratives (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Securities Sold Under Agreements To Repurchase And Other Short Term Borrowings [Line Items]
Maximum aggregate balance outstanding	$ 300,000	$ 100,000
Repurchase Agreements [Member]
Securities Sold Under Agreements To Repurchase And Other Short Term Borrowings [Line Items]
Accrued interest payable on repurchase agreements	1,000	800
Maximum [Member]
Securities Sold Under Agreements To Repurchase And Other Short Term Borrowings [Line Items]
Maximum aggregate balance outstanding	475,800	150,100
Weighted Average [Member]
Securities Sold Under Agreements To Repurchase And Other Short Term Borrowings [Line Items]
Average balance outstanding	$ 291,500	$ 110,600
Weighted Average [Member] | Repurchase Agreements [Member]
Securities Sold Under Agreements To Repurchase And Other Short Term Borrowings [Line Items]
Weighted-average interest rate during the year	2.28%	6.01%