INVESTMENTS (Narrative) (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Schedule of Investments [Line Items]
Trading securities	$ 4,354		$ 4,354			$ 4,161
Debt Securities, Available-for-sale, Allowance for Credit Loss	0		0			0
Net unrealized gain on available-for-sale debt securities, net of tax	14,097	$ 29,310	14,097	$ 29,310	$ 11,801	29,310	$ 22,180	$ 3,250
Deferred tax assets, unrealized losses on available for sale securities	3,900		3,900			8,000
Debt Securities, Available-for-sale, Realized Gain (Loss)	0	$ 0	0	$ 0
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0		0			0
Debt Securities, Held-to-Maturity, Excluded Accrued Interest from Amortized Cost	10		10			10
Security pledged as collateral, amortized cost	500,800		500,800			485,000
Security pledged as collateral, fair value	512,900		512,900			507,100
Available-for-sale Securities
Schedule of Investments [Line Items]
Interest Receivable	$ 3,300		$ 3,300			$ 3,100