ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Net Accumulated Other Comprehensive Income (Loss)) (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (15,754,000)	$ (6,857,000)	$ (6,614,000)
Current period change in other comprehensive income, net of tax	11,422,000	(7,420,000)	(243,000)
Reclassfication of tax effects from accumulated other comprehensive income		(1,477,000)
Ending Balance	(4,332,000)	(15,754,000)	(6,857,000)
Unrealized Gains (Losses) on Investments Available-for-Sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(6,630,000)	687,000	1,642,000
Current period change in other comprehensive income, net of tax	10,630,000	(7,465,000)	(955,000)
Reclassfication of tax effects from accumulated other comprehensive income		148,000
Ending Balance	4,000,000	(6,630,000)	687,000
Defined Benefit Pension Plan
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(9,124,000)	(7,544,000)	(8,256,000)
Current period change in other comprehensive income, net of tax	792,000	45,000	712,000
Reclassfication of tax effects from accumulated other comprehensive income		(1,625,000)
Ending Balance	$ (8,332,000)	$ (9,124,000)	$ (7,544,000)