EMPLOYEE BENEFIT PLANS (Details 2) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
PLAN ASSETS
Fair value of plan assets	$ 96,818	$ 86,718	$ 67,284
Oil and Gas Properties
PLAN ASSETS
Fair value of plan assets	287	299	275
Total Measure at Fair Value
PLAN ASSETS
Fair value of plan assets	96,818	86,718
Total Measure at Fair Value | Short-term investments
PLAN ASSETS
Fair value of plan assets	1,983	7,233
Total Measure at Fair Value | Mutual funds:
PLAN ASSETS
Fair value of plan assets	80,397	67,736
Total Measure at Fair Value | Domestic stock funds
PLAN ASSETS
Fair value of plan assets	44,129	36,209
Total Measure at Fair Value | Bond funds
PLAN ASSETS
Fair value of plan assets	23,749	21,458
Total Measure at Fair Value | International stock funds
PLAN ASSETS
Fair value of plan assets	12,519	10,069
Total Measure at Fair Value | Domestic common stock
PLAN ASSETS
Fair value of plan assets	12,998	10,543
Total Measure at Fair Value | Foreign equity stock
PLAN ASSETS
Fair value of plan assets	1,153	907
Total Measure at Fair Value | Oil and Gas Properties
PLAN ASSETS
Fair value of plan assets	287	299
Quoted Prices in Active Markets for Identical Assets (Level 1)
PLAN ASSETS
Fair value of plan assets	96,531	86,419
Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term investments
PLAN ASSETS
Fair value of plan assets	1,983	7,233
Quoted Prices in Active Markets for Identical Assets (Level 1) | Mutual funds:
PLAN ASSETS
Fair value of plan assets	80,397	67,736
Quoted Prices in Active Markets for Identical Assets (Level 1) | Domestic stock funds
PLAN ASSETS
Fair value of plan assets	44,129	36,209
Quoted Prices in Active Markets for Identical Assets (Level 1) | Bond funds
PLAN ASSETS
Fair value of plan assets	23,749	21,458
Quoted Prices in Active Markets for Identical Assets (Level 1) | International stock funds
PLAN ASSETS
Fair value of plan assets	12,519	10,069
Quoted Prices in Active Markets for Identical Assets (Level 1) | Domestic common stock
PLAN ASSETS
Fair value of plan assets	12,998	10,543
Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign equity stock
PLAN ASSETS
Fair value of plan assets	1,153	907
Significant Unobservable Inputs (Level 3)
PLAN ASSETS
Fair value of plan assets	287	299
Significant Unobservable Inputs (Level 3) | Oil and Gas Properties
PLAN ASSETS
Fair value of plan assets	$ 287	$ 299