RELINQUISHMENT AGREEMENT (Details) (USD $)	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 1998
RELINQUISHMENT AGREEMENT [Abstract]
Term of relinquishment agreement	15 years
Period following the end of the first three-month period after the relinquishment date upon which senior relinquishment payments start	25 days
Period following the end of the first six-month period after the relinquishment date upon which junior relinquishment payments start	25 days
Relinquishment payment rate as a percent of revenues	2.50%
Relinquishment liability	$ 25,200,000	$ 74,400,000		$ 549,100,000
Relinquishment liability reassessment	1,905,000	249,000	11,439,000
Accretion of discount to the relinquishment liability	2,205,000	4,974,000	8,248,000
Relinquishment Payments [Abstract]
Principal	46,574,000	45,350,000	45,258,000
Accretion of discount	2,897,000	5,792,000	9,028,000
Total relinquishment payments	49,500,000	51,200,000	54,300,000
Accrued relinquishment payments	$ 13,200,000	$ 13,300,000