PENSION AND OTHER POST-RETIREMENT BENEFIT PLANS - PENSION PLAN ASSETS WITHIN THE FAIR VALUE HIERARCHY (Details) - Pension Benefits - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 1,023,676	$ 1,041,902	$ 1,136,943
Quoted prices in active markets of identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	20,792	467,085
Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	1,002,884	574,817
Significant other unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	10,116	32,152
Cash and cash equivalents | Quoted prices in active markets of identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	576	1,763
Cash and cash equivalents | Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	9,540	30,389
Cash and cash equivalents | Significant other unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
U.S. all-cap
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		138,367
U.S. all-cap | Quoted prices in active markets of identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		0
U.S. all-cap | Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		138,367
U.S. all-cap | Significant other unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		0
International all-cap
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		111,980
International all-cap | Quoted prices in active markets of identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		108,862
International all-cap | Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		3,118
International all-cap | Significant other unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets		0
Global all-cap
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	262,430	269,220
Global all-cap | Quoted prices in active markets of identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	20,216	73,157
Global all-cap | Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	242,214	196,063
Global all-cap | Significant other unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
U.S. government/agency
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	228,648	237,514
U.S. government/agency | Quoted prices in active markets of identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	117,378
U.S. government/agency | Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	228,648	120,136
U.S. government/agency | Significant other unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	199,634	139,224
Corporate bonds | Quoted prices in active markets of identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	101,476
Corporate bonds | Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	199,634	37,748
Corporate bonds | Significant other unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
Collateralized obligations
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	50,532	40,689
Collateralized obligations | Quoted prices in active markets of identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	32,532
Collateralized obligations | Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	50,532	8,157
Collateralized obligations | Significant other unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	0
International government/corporate bonds
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	30,928	72,756
International government/corporate bonds | Quoted prices in active markets of identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	31,917
International government/corporate bonds | Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	30,928	40,839
International government/corporate bonds | Significant other unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0	$ 0
Global diversified assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	146,975
Global diversified assets [Member] | Quoted prices in active markets of identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0
Global diversified assets [Member] | Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	146,975
Global diversified assets [Member] | Significant other unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0
Global real estate investment trusts [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	48,000
Global real estate investment trusts [Member] | Quoted prices in active markets of identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0
Global real estate investment trusts [Member] | Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	48,000
Global real estate investment trusts [Member] | Significant other unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0
Global infrastructure [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	46,413
Global infrastructure [Member] | Quoted prices in active markets of identical assets (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	0
Global infrastructure [Member] | Significant other observable inputs (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	46,413
Global infrastructure [Member] | Significant other unobservable inputs (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Fair Value of Plan Assets	$ 0