XML 101 R78.htm IDEA: XBRL DOCUMENT
v3.22.4

BUSINESS COMBINATION AND REVERSE RECAPITALIZATION - Common Shares Issued and Outstanding (Details) - USD ($) $ in Thousands |  | 12 Months Ended
--- | --- | ---
Nov. 17, 2020 | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Business Acquisition [Line Items] |  |  |  |
Total outstanding (shares) | 149,308,637 | 177,706,608 | 177,816,554 |
Total issued (shares) | 149,308,637 | 177,706,608 | 177,816,554 |
Payment of underwriting and transaction costs |  | $ 0 | $ 0 | $ 40,325
Shenghe |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Shares issued, warrant exercised | 5,384,563 |  |  |
FVAC public stockholders |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Total outstanding (shares) | 34,464,151 |  |  |
Total issued (shares) | 34,464,151 |  |  |
Gross proceeds sale of shares | $ 344,700 |  |  |
Net proceeds sale of shares | 332,600 |  |  |
Payment of underwriting and transaction costs | $ 12,100 |  |  |
Private Placement Warrants |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Total outstanding (shares) | 890,000 |  |  |
Total issued (shares) | 890,000 |  |  |
MPMO unitholders |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Total outstanding (shares) | 71,941,538 |  |  |
Total issued (shares) | 71,941,538 |  |  |
SNR unitholders |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Total outstanding (shares) | 19,999,942 |  |  |
Total issued (shares) | 19,999,942 |  |  |
PIPE Financing |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Total outstanding (shares) | 20,000,000 |  |  |
Total issued (shares) | 20,000,000 |  |  |
Restricted stock issued to certain MPMO executives |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Total outstanding (shares) | 2,013,006 |  |  |
Total issued (shares) | 2,013,006 |  |  |

X
- Definition Sale of Stock, Consideration Received on Transaction, Gross + References No definition available. + Details
Name: | mp_SaleOfStockConsiderationReceivedOnTransactionGross
Namespace Prefix: | mp_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Stock Issued During Period, Shares, Warrants Redeemed + References No definition available. + Details
Name: | mp_StockIssuedDuringPeriodSharesWarrantsRedeemed
Namespace Prefix: | mp_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

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

X
- Definition Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury. + 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 https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_CommonStockSharesIssued
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI https://asc.fasb.org/extlink&oid=126973232&loc=d3e21463-112644 Reference 2: 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 https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_CommonStockSharesOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition The cash outflow for cost incurred directly with the issuance of an equity security. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 15 -URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3291-108585 + Details
Name: | us-gaap_PaymentsOfStockIssuanceCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Cash received on stock transaction after deduction of issuance costs. + References No definition available. + Details
Name: | us-gaap_SaleOfStockConsiderationReceivedOnTransaction
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | srt_CounterpartyNameAxis=mp_LeshanShengheRareEarthCoLtdMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=mp_FortressValueAcquisitionCorpPublicStockholdersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=mp_PrivatePlacementWarrantsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=mp_MPMineOperationsLLCUnitholdersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=mp_SecureNaturalResourcesLLCUnitholdersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=mp_PIPEFinancingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=mp_RestrictedStockMPMineOperationsLLCExecutivesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |