Redemption period where loyalty program awards are recognized as revenue if not redeemed.

No definition available.

Name:	amch_CustomerLoyaltyProgramRedemptionPeriod
Namespace Prefix:	amch_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130531-203044

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130532-203044

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

+ Details

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

- Definition

Amount of revenue recognized arising from contract liability from change in timeframe for performance obligation to be satisfied.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130551-203045

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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

- Details

Name:	srt_ProductOrServiceAxis=amch_GiftCardAndTicketExchangeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ProductOrServiceAxis=amch_LoyaltyProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	amch_EquityMethodInvestmentActivityByClassificationAxis=amch_ExhibitorServicesAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=amch_RemainderOfFiscalYearMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=amch_YearTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=amch_YearThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=amch_YearFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=amch_YearFiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=amch_ThereafterMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

REVENUE RECOGNITION - Additional disclosures (Details) - USD ($) $ in Millions	1 Months Ended	9 Months Ended
	Jan. 31, 2018	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenues and income		$ 293.2	$ 391.0	$ 401.0
Redemption period		9 months
Gift Card And Ticket Exchange
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenues and income	$ 220.8
Redemption period	24 years
Loyalty Program
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenues and income	$ 45.6
Redemption period	24 months
Exhibitor Services Agreement \| Nine Months Ended December 31, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Expected to be recognized as revenue		$ 3.7
Exhibitor Services Agreement \| Year Ended 2019
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Expected to be recognized as revenue		15.7
Exhibitor Services Agreement \| Year Ended 2020
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Expected to be recognized as revenue		16.8
Exhibitor Services Agreement \| Year Ended 2021
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Expected to be recognized as revenue		18.1
Exhibitor Services Agreement \| Year Ended 2022
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Expected to be recognized as revenue		19.4
Exhibitor Services Agreement \| Years Ended 2023 through February 2037
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Expected to be recognized as revenue		$ 494.0