BENEFIT PLANS (Employer Contributions for Plan) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 4,682	$ 5,029	$ 6,099
2021 (estimated)	4,471
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	8,819	8,882	$ 109,631
Employer contributions	154,691	$ 52,600
2021 (estimated)	$ 8,060