OTHER COMPREHENSIVE INCOME (Amounts Reclassified from Accumulated Other Comprehensive Income to Earnings) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ (33,244)	$ (38,455)	$ (71,018)	$ (72,531)
Other nonoperating income	3,339	3,890	8,421	7,934
Benefit from income taxes	40,046	45,652	35,143	42,477
Total	159,652	120,139	212,631	165,060
Reclassification From AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total	1,144	755	2,301	1,502
Interest Rate Hedge Losses [Member] | Reclassification From AOCI [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest expense	71	539	160	1,067
Benefit from income taxes	(19)	(211)	(42)	(420)
Total	52	328	118	647
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	2,953	1,406
Benefit from income taxes	(385)	(276)	(770)	(551)
Total	$ 1,092	$ 427	$ 2,183	$ 855