Common Stock and Warrants - Schedule of Stockholders Equity Note Warrants or Rights Fair Value of Vested Warrants (Details) $ in Thousands	6 Months Ended
Jun. 30, 2022 USD ($)
Statement [Line Items]
Fair value	$ 174,297
Capitalized at June 30, 2022	160,908
Milestone (a)
Statement [Line Items]
Fair value	58,041
Capitalized at June 30, 2022	58,041
Milestone (b)
Statement [Line Items]
Fair value	58,041
Capitalized at June 30, 2022	58,041
Milestone (c)
Statement [Line Items]
Fair value	58,215
Capitalized at June 30, 2022	$ 44,826

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.

No definition available.

+ Details

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

- Definition

Amount of cost capitalized for award under share-based payment arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

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

- Definition

Fair value portion of warrants not settleable in cash classified as equity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

+ Details

Name:	us-gaap_WarrantsNotSettleableInCashFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	fsr_MilestoneAxis=fsr_MilestoneAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	fsr_MilestoneAxis=fsr_MilestoneBMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	fsr_MilestoneAxis=fsr_MilestoneCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: