RELINQUISHMENT AGREEMENT (Details) (USD $)	9 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Sep. 30, 2011	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	$ 149,800,000		$ 178,300,000	$ 549,100,000
Relinquishment Payments [Abstract]
Principal	28,756,000	26,354,000
Accretion of discount	5,935,000	8,119,000
Total relinquishment payments	34,700,000	34,400,000
Accrued relinquishment payments	$ 19,600,000		$ 14,700,000