POSTRETIREMENT BENEFITS (plan assets) (Details) - Postretirement benefit plan [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Postretirement benefits [Line Items]
Allocation of plan assets	100.00%	100.00%
Fair value of plan assets	$ 129,918	$ 114,976	$ 127,443
Quoted prices in active markets for identical assets (Level 1) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	25,616	30,003
Significant other observable inputs (Level 2) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	81,350	39,450
Significant unobservable inputs (Level 3) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	0	0
Investments measured at net asset value [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	$ 22,952	$ 45,523
Equity securities [Member] | U.S. [Member]
Postretirement benefits [Line Items]
Allocation of plan assets	24.00%	23.00%
Target allocation of plan assets	24.00%
Fair value of plan assets	$ 30,990	$ 26,240
Equity securities [Member] | Quoted prices in active markets for identical assets (Level 1) [Member] | U.S. [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	0	0
Equity securities [Member] | Significant other observable inputs (Level 2) [Member] | U.S. [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	30,990	0
Equity securities [Member] | Significant unobservable inputs (Level 3) [Member] | U.S. [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	0	0
Equity securities [Member] | Investments measured at net asset value [Member] | U.S. [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	$ 0	$ 26,240
Mortgage-backed securities [Member]
Postretirement benefits [Line Items]
Allocation of plan assets	24.00%	25.00%
Fair value of plan assets	$ 30,828	$ 28,731
Mortgage-backed securities [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	0	0
Mortgage-backed securities [Member] | Significant other observable inputs (Level 2) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	13,060	13,593
Mortgage-backed securities [Member] | Significant unobservable inputs (Level 3) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	0	0
Mortgage-backed securities [Member] | Investments measured at net asset value [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	$ 17,768	$ 15,138
International equity securities [Member]
Postretirement benefits [Line Items]
Allocation of plan assets	19.00%	18.00%
Target allocation of plan assets	18.00%
Fair value of plan assets	$ 24,032	$ 20,559
International equity securities [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	20,859	20,261
International equity securities [Member] | Significant other observable inputs (Level 2) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	3,173	298
International equity securities [Member] | Significant unobservable inputs (Level 3) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	0	0
International equity securities [Member] | Investments measured at net asset value [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	$ 0	$ 0
U.S. corporate debt securities [Member]
Postretirement benefits [Line Items]
Allocation of plan assets	15.00%	20.00%
Fair value of plan assets	$ 19,955	$ 22,551
U.S. corporate debt securities [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	0	6,489
U.S. corporate debt securities [Member] | Significant other observable inputs (Level 2) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	14,771	12,468
U.S. corporate debt securities [Member] | Significant unobservable inputs (Level 3) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	0	0
U.S. corporate debt securities [Member] | Investments measured at net asset value [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	$ 5,184	$ 3,594
Government debt securities [Member]
Postretirement benefits [Line Items]
Allocation of plan assets	14.00%	11.00%
Fair value of plan assets	$ 18,776	$ 12,738
Government debt securities [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	0	0
Government debt securities [Member] | Significant other observable inputs (Level 2) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	18,776	12,738
Government debt securities [Member] | Significant unobservable inputs (Level 3) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	0	0
Government debt securities [Member] | Investments measured at net asset value [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	$ 0	$ 0
Equity securities small and midcap [Member] | U.S. [Member]
Postretirement benefits [Line Items]
Allocation of plan assets	4.00%	3.00%
Target allocation of plan assets	3.00%
Fair value of plan assets	$ 4,591	$ 3,837
Equity securities small and midcap [Member] | Quoted prices in active markets for identical assets (Level 1) [Member] | U.S. [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	4,228	3,259
Equity securities small and midcap [Member] | Significant other observable inputs (Level 2) [Member] | U.S. [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	363	27
Equity securities small and midcap [Member] | Significant unobservable inputs (Level 3) [Member] | U.S. [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	0	0
Equity securities small and midcap [Member] | Investments measured at net asset value [Member] | U.S. [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	0	551
Other debt securities [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	746	320
Other debt securities [Member] | Quoted prices in active markets for identical assets (Level 1) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	529	(6)
Other debt securities [Member] | Significant other observable inputs (Level 2) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	217	326
Other debt securities [Member] | Significant unobservable inputs (Level 3) [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	0	0
Other debt securities [Member] | Investments measured at net asset value [Member]
Postretirement benefits [Line Items]
Fair value of plan assets	$ 0	$ 0
Fixed income securities [Member]
Postretirement benefits [Line Items]
Target allocation of plan assets	55.00%