COMMITMENTS AND CONTINGENCIES (Details) (USD $)	0 Months Ended	3 Months Ended		9 Months Ended
	Jun. 30, 2012	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Sep. 30, 2011
Slot Win Contributions [Member]
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
Limitation of excluded free promotional play as a percent of gross revenues from slot machines	11.00%	5.50%
Contribution rate applied to excess free promotional play revenues in excess of limitation, if other than standard rate		25.00%
Slot win contributions		43,600,000	46,800,000	130,400,000	135,400,000
Slot win contributions outstanding	14,600,000	14,600,000		14,600,000		15,300,000
Pennsylvania Slot Machine Tax [Member]
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
Escrow deposit for tax payments	1,500,000	1,500,000		1,500,000
Slot machine tax expense recognized		33,500,000	32,400,000	100,800,000	95,500,000
Slot machine tax expense, outstanding	3,900,000	3,900,000		3,900,000		4,800,000
Pennsylvania Slot Machine Tax [Member] | Downs Racing, L.P. [Member]
Commitments and Contingencies [Line Items]
Number of slot machines at Mohegan Sun at Pocono Downs permitted by license				3,000
Number of slot machines at Mohegan Sun at Pocono Downs permitted by license expandable to				5,000
Pennsylvania Table Game Tax [Member]
Commitments and Contingencies [Line Items]
Initial tax rate				14.00%
Additional local tax				2.00%
Initial taxation period				2 years
Subsequent table game tax rate				12.00%
Table game tax expense recognized		1,600,000	1,700,000	5,200,000	4,900,000
Table game tax expense outstanding	117,000	117,000		117,000		87,000
Pennsylvania Regulatory Fee [Member]
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	1,300,000	3,800,000	3,700,000
Regulatory fee outstanding	125,000	125,000		125,000		106,000
Pennsylvania Gaming Control Board Loans [Member]
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				14
Number of authorized gaming facilities that have commenced operations				11
PGCB loan repayment period				10 years
PGCB loan repayment expense		166,000	676,000	504,000	676,000
Horsemen's Agreement [Member]
Commitments and Contingencies [Line Items]
Purses earned by horsemen and other fees outstanding	9,500,000	9,500,000		9,500,000		9,200,000
Priority Distribution Agreement [Member]
Commitments and Contingencies [Line Items]
Annual limit of priority distribution payments				14,000,000
Priority distribution payments		$ 4,700,000	$ 4,600,000	$ 14,000,000	$ 13,700,000