INCOME TAXES (Deferred) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Accrued expenses	$ 50,351	$ 51,996
Pension liabilities	10,797	9,022
Postretirement liabilities other than pensions	9,552	8,589
Share-based compensation	6,926	6,310
Federal and state net operating loss carryforwards	2,185	2,840
Other	2,032	1,654
Total deferred tax assets	81,843	80,411
Valuation allowance	(354)	(332)
Total deferred tax assets, net of valuation allowance	81,489	80,079
Deferred tax liabilities:
Amortization, depreciation, and basis differences for property, plant and equipment, and other long-lived assets	84,150	64,522
Intangibles	28,272	31,398
Revenue recognition	4,176	3,944
Prepaid expenses	4,503	4,393
Total deferred tax liabilities	121,101	104,257
Net deferred tax liabilities	$ (39,612)	$ (24,178)