EMPLOYEE BENEFIT PLANS - DEFINED BENEFIT PLANS (Details) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Components of net periodic cost
Defined benefit plan, contributions by employer			$ 0	$ 0
Pension [Member]
Components of net periodic cost
Service cost	$ 1,872,000	$ 1,536,000	5,614,000	4,608,000
Interest cost	2,549,000	2,517,000	7,649,000	7,550,000
Expected return on plan assets	(4,272,000)	(3,869,000)	(12,817,000)	(11,607,000)
Recognized actuarial loss	1,747,000	1,399,000	5,239,000	4,197,000
Prior service cost amortization	28,000	27,000	83,000	83,000
Recognized net initial obligation	0	0	0	0
Net periodic benefit cost	1,924,000	1,610,000	5,768,000	4,831,000
OPEB [Member]
Components of net periodic cost
Service cost	1,063,000	980,000	3,190,000	2,942,000
Interest cost	1,434,000	1,434,000	4,304,000	4,300,000
Expected return on plan assets	(1,245,000)	(1,043,000)	(3,733,000)	(3,130,000)
Recognized actuarial loss	737,000	625,000	2,208,000	1,875,000
Prior service cost amortization	(91,000)	(89,000)	(273,000)	(267,000)
Recognized net initial obligation	0	3,000	0	8,000
Net periodic benefit cost	$ 1,898,000	$ 1,910,000	$ 5,696,000	$ 5,728,000