Percentage of paid in kind interest rate.

No definition available.

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

- Definition

The principal amount of debt for which the PIK interest has been waived under the debt instrument arrangement.

+ References

No definition available.

+ Details

Name:	amch_DebtInstrumentPrincipalAmountForWhichPIKInterestHasBeenWaived
Namespace Prefix:	amch_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of increase (decrease) in interest cost.

+ References

No definition available.

+ Details

Name:	amch_IncreaseDecreaseInInterestCost
Namespace Prefix:	amch_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Number of interest periods.

+ References

No definition available.

+ Details

Name:	amch_NumberOfInterestPeriods
Namespace Prefix:	amch_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of reclassification of commitment fee and deferred charges.

+ References

No definition available.

+ Details

Name:	amch_ReclassificationOfCommitmentFeeAndDeferredCharges
Namespace Prefix:	amch_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Number of stock issued during the period as per commitment.

+ References

No definition available.

+ Details

Name:	amch_StockIssuedDuringPeriodSharesCommitmentShares
Namespace Prefix:	amch_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The fair value of shares issued under commitment.

+ References

No definition available.

+ Details

Name:	amch_StockIssuedDuringPeriodValueCommitmentShares
Namespace Prefix:	amch_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The number of new shares issued in the conversion of stock in a noncash (or part noncash) transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4332-108586

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4313-108586

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4304-108586

+ Details

Name:	us-gaap_ConversionOfStockSharesIssued1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4304-108586

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4332-108586

+ Details

Name:	us-gaap_DebtConversionOriginalDebtAmount1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69C
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 55
-Paragraph 69B
-URI http://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612

+ 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

Fair value amount of debt instrument that was repurchased.

+ References

No definition available.

+ Details

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

- Definition

Face (par) amount of the original debt instrument that was repurchased.

+ References

No definition available.

+ Details

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

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=123467658&loc=d3e12355-112629

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=123467658&loc=d3e12317-112629

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3602-108585

+ Details

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

- Definition

Price of a single share of a number of saleable stocks of a company.

+ References

No definition available.

+ Details

Name:	us-gaap_SharePrice
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of new stock issued during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21463-112644

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_StockIssuedDuringPeriodSharesNewIssues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_StatementClassOfStockAxis=us-gaap_CommonClassAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=amch_MudrickCapitalManagementLpMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=amch_FirstLienToggleNotesDue2026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=amch_DebtAgreementWithMudrickCapitalManagementLpMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=amch_FirstLienSecuredNotesDue2026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=amch_SecondLienNotesDue2026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

CORPORATE BORROWINGS AND FINANCE LEASE OBLIGATIONS - First Lien Toggle Notes due 2026 (Details) $ / shares in Units, $ in Thousands					1 Months Ended	12 Months Ended
	Feb. 01, 2021 shares	Jan. 15, 2021 USD ($) item	Dec. 14, 2020 USD ($) $ / shares shares	Jul. 31, 2020 USD ($) item	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
(Gain) loss on extinguishment of debt						$ 14,100	$ (93,600)	$ 16,600
Principal amount						600,000
Class A common stock
Debt Instrument [Line Items]
Consideration received for conversion \| shares	46,103,784
Mudrick Capital Management LP \| Class A common stock
Debt Instrument [Line Items]
Number of shares issued \| shares			21,978,022
Consideration received for commitment fee \| shares			8,241,758
Fair value of common stock			$ 70,100
Price per share (in dollars per share) \| $ / shares			$ 3.19
First Lien Toggle Notes due 2026
Debt Instrument [Line Items]
Exercised an option to repurchase					$ 35,000
Repurchase amount					40,300
Increase (decrease) in interest cost					$ 5,250
(Gain) loss on extinguishment of debt						$ 14,400
Aggregate principal amount		$ 100,000
Stated interest rate (as a percent)						15.00%	15.00%
PIK interest rate (as a percent)						17.00%
Number of interest periods \| item		3
First Lien Toggle Notes due 2026 \| Mudrick Capital Management LP
Debt Instrument [Line Items]
Stated interest rate (as a percent)		15.00%
PIK interest rate (as a percent)		17.00%
First Lien Toggle Notes due 2026 \| Debt Agreement with Mudrick Capital Management, LP [Member]
Debt Instrument [Line Items]
Stated interest rate (as a percent)		15.00%
PIK interest rate (as a percent)		17.00%
First Lien Secured Notes Due 2026 \| Class A common stock
Debt Instrument [Line Items]
Reclassified prepaid commitment fee and deferred charges						$ 28,600
Second Lien Notes due 2026
Debt Instrument [Line Items]
Aggregate principal amount				$ 1,289,100		$ 173,200
Stated interest rate (as a percent)				10.00%
PIK interest rate (as a percent)				12.00%
Number of interest periods \| item				3
Second Lien Notes due 2026 \| Class A common stock
Debt Instrument [Line Items]
(Gain) loss on extinguishment of debt							$ (93,600)
Consideration received for conversion \| shares							137,400,000
Principal amount							$ 104,500
Fair value of common stock							$ 43,800
Second Lien Notes due 2026 \| Mudrick Capital Management LP
Debt Instrument [Line Items]
Consideration received for conversion \| shares			13,736,264
Principal amount			$ 104,500
Second Lien Notes due 2026 \| Mudrick Capital Management LP \| Class A common stock
Debt Instrument [Line Items]
Principal amount			100,000
Waived off PIK interest			$ 4,500