FAIR VALUE - Change in unrealized losses included in earnings (Detail) - Available-for-sale Securities [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net impairment losses on available-for-sale investment securities credit component	$ (1,641)	$ (497)	$ (50)
Realized gain (loss) on sales of debt securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net impairment losses on available-for-sale investment securities credit component	0	(497)	(50)
Provision For Credit Losses [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net impairment losses on available-for-sale investment securities credit component	$ (1,641)	$ 0	$ 0