XML 73 R50.htm IDEA: XBRL DOCUMENT
v3.22.4

REVENUE RECOGNITION - Significant Activity For Deferred Revenue (Details) - USD ($) $ in Thousands |  | 1 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Jun. 20, 2017 | May 31, 2020 | Dec. 31, 2020 | Dec. 31, 2019
Contract With Customer, Liability, Related Parties [Rollforward] |  |  |  |
Opening balance |  |  | $ 35,543 |
Prepayments received |  |  | 11,050 |
Revenue recognized in exchange for debt principal reduction |  |  | (9,117) |
Effect of June 2020 Modification |  |  | (37,476) |
Ending balance |  |  | $ 0 |
Deferred revenue expected to be realized, current |  |  |  | $ 6,600
Affiliated Entity | Shenghe |  |  |  |
Contract With Customer, Liability, Related Parties [Rollforward] |  |  |  |
Deferred revenue percentage recognized from gross profit | 64.00% |  |  |
Tariff rebates |  | $ 1,400 |  |

X
- Definition Contract With Customer, Liability, Deferred Revenue, Current + References No definition available. + Details
Name: | mp_ContractWithCustomerLiabilityDeferredRevenueCurrent
Namespace Prefix: | mp_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Contract With Customer, Liability, Related Parties, Deferred Revenue + References No definition available. + Details
Name: | mp_ContractWithCustomerLiabilityRelatedPartiesDeferredRevenue
Namespace Prefix: | mp_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Contract With Customer, Liability, Related Parties, Deferred Revenue, Additions + References No definition available. + Details
Name: | mp_ContractWithCustomerLiabilityRelatedPartiesDeferredRevenueAdditions
Namespace Prefix: | mp_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Contract With Customer, Liability, Related Parties, Derecognition From Contract Modification + References No definition available. + Details
Name: | mp_ContractWithCustomerLiabilityRelatedPartiesDerecognitionFromContractModification
Namespace Prefix: | mp_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Contract With Customer, Liability, Related Parties, Revenue Recognized + References No definition available. + Details
Name: | mp_ContractWithCustomerLiabilityRelatedPartiesRevenueRecognized
Namespace Prefix: | mp_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Contract With Customer, Liability, Related Parties + References No definition available. + Details
Name: | mp_ContractWithCustomerLiabilityRelatedPartiesRollForward
Namespace Prefix: | mp_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Contract With Customer, Liability, Related Parties, Tariff Rebates + References No definition available. + Details
Name: | mp_ContractWithCustomerLiabilityRelatedPartiesTariffRebates
Namespace Prefix: | mp_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Related Party Transaction, Deferred Revenue Percentage Recognized From Gross Profit + References No definition available. + Details
Name: | mp_RelatedPartyTransactionDeferredRevenuePercentageRecognizedFromGrossProfit
Namespace Prefix: | mp_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=srt_AffiliatedEntityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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