XML 393 R55.htm IDEA: XBRL DOCUMENT v3.25.1

Commitments and Contingencies - Schedule of Restricted Cash Deposits (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024
Long-term Purchase Commitment [Line Items]
Total long-term restricted cash	$ 124,185	$ 122,583	$ 121,927
Workers’ compensation and black lung obligations
Long-term Purchase Commitment [Line Items]
Total long-term restricted cash	114,094	113,144
Reclamation-related obligations
Long-term Purchase Commitment [Line Items]
Total long-term restricted cash	1,199	697
Financial payments and other performance obligations
Long-term Purchase Commitment [Line Items]
Total long-term restricted cash	$ 8,892	$ 8,742

X

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

X

- Definition

Amount of cash restricted as to withdrawal or usage, classified as noncurrent. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(17))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 5
-SubTopic 210
-Topic 954
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477220/954-210-45-5

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482913/230-10-50-8

+ Details

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

X

- Details

Name:	us-gaap_CollateralAxis=amr_WorkersCompensationAndBlackLungObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_CollateralAxis=amr_ReclamationRelatedObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_CollateralAxis=amr_FinancialPaymentsAndOtherPerformanceObligationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: