Represents the threshold minimum percentage of voting stock.

No definition available.

Name:	amch_ThresholdMinimumPercentageOfVotingStock
Namespace Prefix:	amch_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

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+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

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

- Definition

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

+ References

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-Publisher FASB
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Balance Type:	na
Period Type:	duration

- Definition

Percentage of principal amount of debt redeemed.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

+ References

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+ Details

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

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

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+ Details

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

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=us-gaap_DebtInstrumentRedemptionPeriodTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=amch_FirstLienNotesDue2029Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=us-gaap_DebtInstrumentRedemptionPeriodThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentRedemptionPeriodAxis=amch_DebtRedemptionAtTimeOfSaleOfAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

CORPORATE BORROWINGS AND FINANCE LEASE LIABILITIES - First Lien Notes Due 2029 (Details) - USD ($) $ in Millions			3 Months Ended				12 Months Ended
	Feb. 14, 2022	Apr. 24, 2020	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Principal and premium repayments			$ 529.5	$ 7.4	$ 57.9	$ 955.7
Gain on Extinguishment							$ (92.8)	$ (14.1)	$ 93.6
Debt Instrument, Redemption Price as Percentage of Principal Amount	107.50%
Redemption period two
Debt Instrument [Line Items]
Debt instrument redemption amount as a percentage of principal amount		100.00%
First Lien Notes due 2029
Debt Instrument [Line Items]
Aggregate principal amount	$ 950.0
Stated interest rate (as a percent)	7.50%		7.50%				7.50%	7.50%
Gain on Extinguishment							$ 135.0
Debt Instrument, Redemption Price as Percentage of Principal Amount	101.00%
Threshold Minimum Percentage of Voting Stock	65.00%
First Lien Notes due 2029 \| Redemption period one
Debt Instrument [Line Items]
Debt instrument redemption amount as a percentage of principal amount	103.75%
First Lien Notes due 2029 \| Redemption period two
Debt Instrument [Line Items]
Debt instrument redemption amount as a percentage of principal amount	101.875%
First Lien Notes due 2029 \| Redemption period three
Debt Instrument [Line Items]
Debt instrument redemption amount as a percentage of principal amount	100.00%
First Lien Notes due 2029 \| At the time of sale of assets
Debt Instrument [Line Items]
Debt Instrument, Redemption Price as Percentage of Principal Amount	35.00%
Debt instrument redemption amount as a percentage of principal amount	100.00%