EMPLOYEE BENEFIT PLANS, FAIR VALUE (Details) - USD ($) $ in Thousands		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets	[1]	$ 199,123	$ 211,653	$ 200,236
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		57,269	56,909	$ 49,555
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		199,123	211,653
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Pension [Member] | Money Market Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		0	50
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Pension [Member] | Large Cap Index Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		63,285	70,358
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Pension [Member] | Extended Market Index [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		11,827	12,475
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Pension [Member] | International Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		37,353	41,833
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Pension [Member] | Emerging Markets Debt Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		8,857	10,029
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Pension [Member] | Core Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Pension [Member] | Opportunistic Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Pension [Member] | Ultra Short Duration [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Pension [Member] | High Yield Bond Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		20,532	21,054
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Pension [Member] | Long Duration Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		57,269	55,854
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		57,269	56,909
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | OPEB [Member] | Money Market Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		2,237	1,154
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | OPEB [Member] | Large Cap Index Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		17,460	19,092
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | OPEB [Member] | Extended Market Index [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		3,762	3,733
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | OPEB [Member] | International Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		10,261	10,309
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | OPEB [Member] | Emerging Markets Debt Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		2,617	2,798
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | OPEB [Member] | Core Fixed Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		7,148	6,522
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | OPEB [Member] | Opportunistic Income [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		4,179	3,960
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | OPEB [Member] | Ultra Short Duration [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		3,960	3,761
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | OPEB [Member] | High Yield Bond Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		5,645	5,580
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | OPEB [Member] | Long Duration Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, fair value of plan assets		$ 0	$ 0

[1] Includes the Company's PEP.