BENEFIT PLANS (Combined Funded Status of Plans and their Reconciliation with Related Amounts Recognized in Consolidated Financial Statements) (Details) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in Benefit Obligation
Projected benefit obligation at beginning of year	$ 958,936	$ 1,091,223
Service cost	4,995	5,716	$ 6,715
Interest cost	37,640	35,503	36,230
Actuarial (gain) loss	141,922	(118,827)
Benefits paid	(52,600)	(54,679)
Projected benefit obligation at end of year	1,090,893	958,936	1,091,223
Change in Fair Value of Plan Assets
Fair value of assets at beginning of year	836,770	840,901
Actual return on plan assets	155,955	(59,083)
Employer contributions	8,882	109,631	20,023
Benefits paid	(52,600)	(54,679)
Fair value of assets at end of year	949,007	836,770	$ 840,901
Funded status	(141,886)	(122,166)
Amounts Recognized in the Consolidated Balance Sheets
Noncurrent assets	9,056	6,488
Current liabilities	(8,579)	(9,067)
Noncurrent liabilities	(142,363)	(119,587)
Net amount recognized	(141,886)	(122,166)
Amounts Recognized in Accumulated Other Comprehensive Income
Net actuarial loss	268,483	240,199
Prior service cost	6,488	7,828
Total amount recognized	$ 274,971	$ 248,027