COMMITMENTS AND CONTINGENCIES (Details)	3 Months Ended		9 Months Ended
	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Jun. 30, 2015 USD ($) gaming_facility slot_machine	Jun. 30, 2014 USD ($)	Sep. 30, 2014 USD ($)
Slot Win Contributions
Commitments and Contingencies [Line Items]
Contribution frequency period			12 months
Contribution determination criteria 1, percent of gross revenues from slot machines, lesser of			30.00%
Contribution determination criteria 2a, lesser of, percent of gross revenues from slot machines, greater of			25.00%
Contribution determination criteria 2b, lesser of, set cash contribution			$ 80,000,000.0
Contribution rate applied to excess free promotional play revenues in excess of limitation, if other than standard rate			25.00%
Limitation of excluded free promotional play as a percent of gross revenues from slot machines			11.00%
Slot win contributions	$ 37,000,000	$ 36,600,000	$ 107,800,000	$ 107,600,000
Slot win contributions outstanding	11,700,000		$ 11,700,000		$ 11,600,000
Pennsylvania Slot Machine Tax
Commitments and Contingencies [Line Items]
Tax rate applied to percent of gross revenues from slot machines			55.00%
Portion of taxed revenues subject to minimum annual local share assessment			2.00%
Minimum annual local share assessment			$ 10,000,000.0
Escrow deposit for tax payments	1,500,000		1,500,000
Slot machine tax expense recognized	31,100,000	31,400,000	88,700,000	91,800,000
Slot machine tax expense, outstanding	3,300,000		$ 3,300,000		4,600,000
Pennsylvania Slot Machine Tax | Downs Racing, L.P.
Commitments and Contingencies [Line Items]
Number of slot machines at Mohegan Sun at Pocono permitted by license | slot_machine			3,000
Permitted slot machine capacity (in slot machines) | slot_machine			5,000
Pennsylvania Table Game Tax
Commitments and Contingencies [Line Items]
Initial tax rate			12.00%
Additional local tax			2.00%
Table game tax expense recognized	1,800,000	1,600,000	$ 5,200,000	4,600,000
Table game tax expense outstanding	168,000		$ 168,000		156,000
Pennsylvania Regulatory Fee
Commitments and Contingencies [Line Items]
Fee rate, percent of gross revenues from slot machines and table games			1.50%
Regulatory fee recognized	1,200,000	1,200,000	$ 3,400,000	3,500,000
Regulatory fee outstanding	147,000		147,000		147,000
Pennsylvania Gaming Control Board Loans
Commitments and Contingencies [Line Items]
Loans granted by PGCB			36,100,000
Additional Loans granted by PGCB			$ 63,800,000
Number of authorized gaming facilities | gaming_facility			14
Number of authorized gaming facilities that have commenced operations | gaming_facility			12
PGCB loan repayment period			10 years
PGCB loan repayment expense	155,000	159,000	$ 468,000	479,000
Horsemen's Agreement
Commitments and Contingencies [Line Items]
Purses earned by horsemen and other fees outstanding	8,300,000		8,300,000		$ 8,100,000
Priority Distribution Agreement
Commitments and Contingencies [Line Items]
Annual limit of priority distribution payments			40,000,000
Priority distribution payments	$ 10,000,000	$ 4,900,000	$ 21,500,000	$ 14,600,000