BASIS OF PRESENTATION - Reserves For Doubtful Collection of Long-term Receivables (Details) (Allowance for Notes Receivable, USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Jun. 30, 2013	Jun. 30, 2013
Allowance for Notes, Loans and Financing Receivable, Noncurrent [Roll Forward]
Balance, beginning of period	$ 23,023	$ 21,877
Additions: Charges to bad debt expense	576	1,727
Deductions: Adjustments	(2)	(7)
Balance, end of period	23,597	23,597
Affiliates
Allowance for Notes, Loans and Financing Receivable, Noncurrent [Roll Forward]
Balance, beginning of period	22,958	21,807
Additions: Charges to bad debt expense	576	1,727
Deductions: Adjustments	0	0
Balance, end of period	23,534	23,534
Tenants and Others
Allowance for Notes, Loans and Financing Receivable, Noncurrent [Roll Forward]
Balance, beginning of period	65	70
Additions: Charges to bad debt expense	0	0
Deductions: Adjustments	(2)	(7)
Balance, end of period	$ 63	$ 63

Name:	mtga_AllowanceForNotesLoansAndFinancingReceivableNoncurrentRollForward
Namespace Prefix:	mtga_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

A valuation allowance relating to a written agreement to receive money (at a specified future date(s) more than one year from the reporting date, consisting of principal as well as any accrued interest) for the portion that is expected to be uncollectible.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=7512638&loc=d3e5074-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 4

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.4)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_AllowanceForNotesAndLoansReceivableNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Total of the adjustments in a given period to allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 09

-Article 12

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e24092-122690

+ Details

Name:	us-gaap_ValuationAllowancesAndReservesAdjustments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Total of allowances and reserves, the valuation and qualifying accounts that are either netted against the cost of an asset (in order to value it at its carrying value) or that reflect a liability established to represent expected future costs, charged to costs and expenses.

+ References

+ Details

Name:	us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration