XML 394 R56.htm IDEA: XBRL DOCUMENT v3.25.1

Commitments and Contingencies - Schedule of Restricted Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Long-term Purchase Commitment [Line Items]
Total restricted investments	$ 42,960	$ 43,131
Workers’ compensation obligations
Long-term Purchase Commitment [Line Items]
Total restricted investments	3,134	3,119
Reclamation-related obligations
Long-term Purchase Commitment [Line Items]
Total restricted investments	33,803	34,018
Financial payments and other performance obligations
Long-term Purchase Commitment [Line Items]
Total restricted investments	$ 6,023	$ 5,994

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

Investments which are not defined as or included in marketable (debt, equity, or other) securities whose use is restricted in whole or in part, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 954
-SubTopic 210
-Name Accounting Standards Codification
-Section 45
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477220/954-210-45-4

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 954
-SubTopic 210
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478600/954-210-50-2

+ Details

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

X

- Details

Name:	us-gaap_CollateralAxis=amr_WorkersCompensationObligationsMember
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: