XML 89 R76.htm IDEA: XBRL DOCUMENT v3.24.3

RELATED PARTY TRANSACTIONS - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended		9 Months Ended
	Jan. 31, 2024	Oct. 31, 2023	Mar. 31, 2022	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Related Party Transaction [Line Items]
Purchases from related party				$ 1,800	$ 5,800	$ 4,100	$ 7,600
Accounts receivable				14,549		14,549		$ 10,029
Related party
Related Party Transaction [Line Items]
Accounts receivable				$ 8,200		$ 8,200		$ 9,200
Offtake Agreement
Related Party Transaction [Line Items]
Initial term			2 years
Extension period			1 year
VREX Tolling Agreement
Related Party Transaction [Line Items]
Initial term		3 years
Extension period		3 years
2024 Offtake Agreement
Related Party Transaction [Line Items]
Initial term	2 years
Extension period	1 year

X

- Definition

Related Party Transactions. Extension Period

+ References

No definition available.

+ Details

Name:	mp_RelatedPartyTransactionsExtensionPeriod
Namespace Prefix:	mp_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Related Party Transactions, Initial Term

+ References

No definition available.

+ Details

Name:	mp_RelatedPartyTransactionsInitialTerm
Namespace Prefix:	mp_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481990/310-10-45-2

+ Details

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

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481990/310-10-45-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c)(2)(i))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c)(2)(ii))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(g)(3))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

+ Details

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

X

- Definition

Purchases during the period (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

No definition available.

+ Details

Name:	us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_RelatedPartyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=mp_A2022OfftakeAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=mp_VREXTollingAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=mp_A2024OfftakeAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: