Leases - Schedule of Minimum Future Rental Payments Expected to Incur under Non-Cancelable Leases and Subleases under Prior Accounting Standards (Details) $ in Thousands	Sep. 30, 2019 USD ($)
Minimum Future Rental Payments
2020	$ 32,504
2021	30,376
2022	30,651
2023	30,473
2024	30,602
Thereafter	715,910
Total	870,516
Minimum Future Sublease Income
2020	(4,808)
2021	(4,038)
2022	(2,485)
2023	(2,092)
2024	(2,011)
Thereafter	(5,734)
Total	(21,168)
Total
2020	30,795
2021	28,948
2022	29,537
2023	29,486
2024	29,577
Thereafter	715,067
Total	863,410
Assets Subleased
Minimum Future Sublease Income
2020	(1,709)
2021	(1,428)
2022	(1,114)
2023	(987)
2024	(1,025)
Thereafter	(843)
Total	$ (7,106)

Operating Leases Future Minimum Payments Due, Net [Abstract]

No definition available.

Name:	ck1005276_OperatingLeasesFutureMinimumPaymentsDueNetAbstract
Namespace Prefix:	ck1005276_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Operating Leases, Future Minimum Payments Due, Net of Sublease Income

+ References

No definition available.

+ Details

Name:	ck1005276_OperatingLeasesFutureMinimumPaymentsDueNetofSubleaseIncome
Namespace Prefix:	ck1005276_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Operating Leases, Future Minimum Payments Due, Net of Sublease Income, In Five Years

+ References

No definition available.

+ Details

Name:	ck1005276_OperatingLeasesFutureMinimumPaymentsDueNetofSubleaseIncomeInFiveYears
Namespace Prefix:	ck1005276_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Operating Leases, Future Minimum Payments Due, Net of Sublease Income, In Four Years

+ References

No definition available.

+ Details

Name:	ck1005276_OperatingLeasesFutureMinimumPaymentsDueNetofSubleaseIncomeInFourYears
Namespace Prefix:	ck1005276_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Operating Leases, Future Minimum Payments Due, Net of Sublease Income, In Three Years

+ References

No definition available.

+ Details

Name:	ck1005276_OperatingLeasesFutureMinimumPaymentsDueNetofSubleaseIncomeInThreeYears
Namespace Prefix:	ck1005276_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Operating Leases, Future Minimum Payments Due, Net of Sublease Income, In Two Years

+ References

No definition available.

+ Details

Name:	ck1005276_OperatingLeasesFutureMinimumPaymentsDueNetofSubleaseIncomeInTwoYears
Namespace Prefix:	ck1005276_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Operating Leases, Future Minimum Payments Due, Net of Sublease Income, Next Twelve Months

+ References

No definition available.

+ Details

Name:	ck1005276_OperatingLeasesFutureMinimumPaymentsDueNetofSubleaseIncomeNextTwelveMonths
Namespace Prefix:	ck1005276_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Operating Leases, Future Minimum Payments Due, Net of Sublease Income, Thereafter

+ References

No definition available.

+ Details

Name:	ck1005276_OperatingLeasesFutureMinimumPaymentsDueNetofSubleaseIncomeThereafter
Namespace Prefix:	ck1005276_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of required minimum rental payments for leases having an initial or remaining non-cancelable letter-terms in excess of one year.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121573735&loc=d3e41502-112717

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 55
-Paragraph 40
-Subparagraph (Note 3)
-URI http://asc.fasb.org/extlink&oid=121580752&loc=d3e38371-112697

+ Details

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

- References

No definition available.

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

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

- Definition

Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

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

- Definition

Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

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

- Definition

Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 55
-Paragraph 40
-Subparagraph (Note 3)
-URI http://asc.fasb.org/extlink&oid=121580752&loc=d3e38371-112697

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121573735&loc=d3e41502-112717

+ Details

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

- Definition

Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

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

- Definition

Amount of required minimum rental payments for operating leases having an initial or remaining non-cancelable lease term in excess of one year due after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

+ Details

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

- Definition

Future minimum rental payments in aggregate as of the balance sheet date under operating leases.

+ References

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsReceivable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Future rental payments receivable within one year of the balance sheet date under an operating lease.

+ References

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Future rental payments receivable within the fifth year from the balance sheet date under an operating lease.

+ References

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFiveYears
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Future rental payments receivable within the fourth year from the balance sheet date under an operating lease.

+ References

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInFourYears
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Future rental payments receivable within the third year from the balance sheet date under an operating lease.

+ References

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInThreeYears
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Future rental payments receivable within the second year from the balance sheet date under an operating lease.

+ References

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableInTwoYears
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Future minimum lease payments receivable under operating leases for periods greater than five years following the balance sheet date.

+ References

+ Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableThereafter
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_RelatedPartyTransactionDueFromToRelatedPartyAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_MajorPropertyClassAxis=ck1005276_AssetsSubleasedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: