INVESTMENT SECURITIES - Proceeds from Sales and Calls of Securities and Associated Gross Gains and Losses (Detail) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Investments, Debt and Equity Securities [Abstract]
Gross realized gains on sales and calls of securities available-for-sale	$ 0		$ 71	$ 2,011	$ 279
Gross realized losses on sales and calls of securities available-for-sale	0		(5,134)	0	(5,134)
Net realized (losses) gains on sales and calls of securities available-for-sale	0	$ 2,011	(5,063)	2,011	(4,855)
Proceeds from sales and calls of securities available-for-sale	$ 0		$ 43,252	$ 52,727	$ 861,008