EMPLOYEE BENEFIT PLANS (Nonunion Plan Assets - FV) (Details) - Nonunion Defined Benefit Pension Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension and other postretirement benefit plans
Fair value of plan assets	$ 136,917	$ 158,265	$ 207,613
Cash and Cash Equivalents
Pension and other postretirement benefit plans
Fair value of plan assets	19,079	19,085
Debt Instruments
Pension and other postretirement benefit plans
Fair value of plan assets	26,662	32,361
Floating Rate Loan Fund
Pension and other postretirement benefit plans
Fair value of plan assets	15,868	16,106
Large Cap U.S. Equity
Pension and other postretirement benefit plans
Fair value of plan assets	23,459	29,964
Mid Cap U.S. Equity
Pension and other postretirement benefit plans
Fair value of plan assets	14,276	19,180
Small Cap U.S. Equity
Pension and other postretirement benefit plans
Fair value of plan assets	14,135	17,899
International Equity
Pension and other postretirement benefit plans
Fair value of plan assets	23,438	23,670
Level 1
Pension and other postretirement benefit plans
Fair value of plan assets	110,255	125,904
Level 1 | Cash and Cash Equivalents
Pension and other postretirement benefit plans
Fair value of plan assets	19,079	19,085
Level 1 | Floating Rate Loan Fund
Pension and other postretirement benefit plans
Fair value of plan assets	15,868	16,106
Level 1 | Large Cap U.S. Equity
Pension and other postretirement benefit plans
Fair value of plan assets	23,459	29,964
Level 1 | Mid Cap U.S. Equity
Pension and other postretirement benefit plans
Fair value of plan assets	14,276	19,180
Level 1 | Small Cap U.S. Equity
Pension and other postretirement benefit plans
Fair value of plan assets	14,135	17,899
Level 1 | International Equity
Pension and other postretirement benefit plans
Fair value of plan assets	23,438	23,670
Level 2
Pension and other postretirement benefit plans
Fair value of plan assets	26,662	32,361
Level 2 | Debt Instruments
Pension and other postretirement benefit plans
Fair value of plan assets	$ 26,662	$ 32,361
Level 2 | Corporate debt securities
Pension and other postretirement benefit plans
Percentage of investments in debt instruments	74.00%	66.00%
Level 2 | Mortgage-backed instruments
Pension and other postretirement benefit plans
Percentage of investments in debt instruments	17.00%	24.00%
Level 2 | Treasury instruments
Pension and other postretirement benefit plans
Percentage of investments in debt instruments	6.00%	5.00%
Level 2 | Municipal debt securities
Pension and other postretirement benefit plans
Percentage of investments in debt instruments	2.00%	4.00%
Level 2 | Agency securities
Pension and other postretirement benefit plans
Percentage of investments in debt instruments	1.00%	1.00%