INCOME TAXES (Components of Net Deferred Income Tax Liability) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
INCOME TAXES [Abstract]
Employee benefits	$ 85,123	$ 78,999
Asset retirement obligations & other reserves	63,617	59,507
Deferred compensation	103,947	117,298
State and local income taxes, net of federal income tax benefit	54,498	61,658
Federal credit carryforwards	18,139	34,340
Other	44,843	48,856
Total gross deferred tax assets	370,167	400,658
Valuation allowance	(44,237)	(59,323)
Total net deferred tax assets	325,930	341,335
Property, plant & equipment	664,763	665,057
Goodwill/other intangible assets	327,666	324,910
Other	36,355	32,464
Total deferred tax liabilities	1,028,784	1,022,431
Net deferred tax liability	$ 702,854	$ 681,096