INVESTMENTS (Narrative) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Schedule of Investments [Line Items]
Net unrealized gain on available-for-sale debt securities, net of tax	$ 22,180	$ (6,927)	$ 3,250	$ (17,826)
Deferred tax assets, unrealized losses on available for sale securities	$ 6,100		900
Unrealized Loss as a Percent of Fair Value	1.00%
Security pledged as collateral, amortized cost	$ 712,400		709,000
Security pledged as collateral, fair value	735,300		$ 712,400
Unrealized loss, change in fair value of bank stock equity securities	0	243
Debt Securities, Available-for-sale, Realized Gain (Loss)	$ 0	$ 0