OTHER COMPREHENSIVE INCOME (Amounts Reclassified from Accumulated Other Comprehensive Income to Earnings) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense		$ (33,547)	$ (82,041)	$ (104,566)	$ (154,572)
Other nonoperating income		4,890	3,793	12,708	11,709
Benefit from income taxes		40,663	39,080	75,805	81,557
Total		179,151	108,579	391,783	273,639
Reclassification From AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total		1,144	1,615	3,445	3,117
Interest Rate Hedge Losses [Member] | Reclassification From AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense		72	1,955	232	3,022
Benefit from income taxes		(19)	(767)	(61)	(1,186)
Total	[1]	53	1,188	171	1,836
Pension and Postretirement Plan Actuarial Loss and Prior Service Cost [Member] | Reclassification From AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other nonoperating income		1,477	703	4,430	2,109
Benefit from income taxes		(386)	(276)	(1,156)	(828)
Total		$ 1,091	$ 427	$ 3,274	$ 1,281

[1] 1Totals for 2017 include the acceleration of deferred losses on interest rate hedges (see Note 6) referable to debt purchases (see Note 7).