FAIR VALUES OF FINANCIAL INSTRUMENTS - Reconciliation of Assets Measured at Fair Value on Recurring Basis (Detail) - Recurring - Significant Unobservable Inputs (Level 3) - U.S. government agency and U.S. government sponsored enterprise residential mortgage-backed securities - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 16,685	$ 21,075	$ 19,233	$ 25,040
Total gains (losses) (realized/unrealized):
Included in earnings—fair value adjustment	18	2	(1,351)	(1)
Additions	0	406	0	406
Sales, settlements, and other	(15,320)	(978)	(16,499)	(4,940)
Balance at end of period	$ 1,383	$ 20,505	$ 1,383	$ 20,505