SHORT-TERM BORROWINGS (Balances and Rates) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Disclosure [Abstract]
Maximum month-end balance	$ 380,360	$ 226,096	$ 229,890
Average month-end balance	$ 157,348	$ 128,098	$ 152,391
Weighted average interest rate for the year	0.39%	1.38%	1.19%
Weighted average interest rate at year-end	0.18%	1.21%	1.96%