COVER - shares	6 Months Ended
	Jun. 30, 2023	Jul. 31, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2023
Document Transition Report	false
Entity File Number	001-39277
Entity Registrant Name	MP Materials Corp. / DE
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	84-4465489
Entity Address, Address Line One	1700 S. Pavilion Center Drive, Suite 800
Entity Address, City or Town	Las Vegas
Entity Address, State or Province	NV
Entity Address, Postal Zip Code	89135
City Area Code	702
Local Phone Number	844-6111
Title of 12(b) Security	Common Stock, par value of $0.0001 per share
Trading Symbol	MP
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		177,648,549
Amendment Flag	false
Entity Central Index Key	0001801368
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31