EMPLOYEE BENEFIT PLANS, WEIGHTED AVERAGE ASSUMPTIONS (Details)		12 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Pension [Member]
Benefit costs:
Discount rate		4.55%	5.15%	4.30%
Expected asset return		8.75%	8.25%	8.50%
Compensation increase		3.25%	3.25%	3.25%
Obligations:
Discount rate		4.50%	4.55%	5.15%
Compensation increase				3.25%
Pension [Member] | Represented [Member]
Obligations:
Compensation increase	[1]	3.25%	3.25%
Pension [Member] | Nonrepresented [Member]
Obligations:
Compensation increase	[1]	3.50%	3.50%
OPEB [Member]
Benefit costs:
Discount rate		4.55%	5.15%	4.30%
Expected asset return		8.75%	8.25%	8.50%
Compensation increase		3.50%	3.50%	3.25%
Obligations:
Discount rate			4.55%	5.15%
Compensation increase		3.50%	3.50%	3.25%
OPEB [Member] | Represented [Member]
Obligations:
Discount rate	[1]	4.60%
OPEB [Member] | Nonrepresented [Member]
Obligations:
Discount rate	[1]	4.55%

[1] Percentages for represented and nonrepresented plans, respectively.