Percentage investment held by the managing member or general partner of the limited liability company (LLC) or limited partnership (LP).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055

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- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

+ References

No definition available.

+ Details

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- Definition

Amount of income (expense) related to nonoperating activities, classified as other.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.9)
-URI https://asc.fasb.org/extlink&oid=126953954&loc=SL114868664-224227

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- Definition

The cash inflow from the sale of an investment interest in a joint venture that the reporting entity has not previously accounted for using consolidation or the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3179-108585

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- Definition

Amount of transactions with related party during the financial reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
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-Topic 850
-SubTopic 10
-Section 50
-Paragraph 3
-URI https://asc.fasb.org/extlink&oid=6457730&loc=d3e39603-107864

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- 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.

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Name:	dei_LegalEntityAxis=psix_MATPSIHoldingsLLCMember
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Name:	srt_OwnershipAxis=psix_DoosanPSILLCMember
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Related Party Transactions (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2012	Jun. 30, 2021	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2015
Related Party Transaction [Line Items]
Return of investment in joint venture			$ 0	$ 2,263
Other expense, net			0	(1)
Corporate Joint Venture
Related Party Transaction [Line Items]
Other expense, net			$ 0	$ 100
Corporate Joint Venture \| Green Power
Related Party Transaction [Line Items]
Investment amount with related party	$ 900
Percent of noncontrolling interest	50.00%
Corporate Joint Venture \| Green Power \| MAT-PSI Holdings, LLC
Related Party Transaction [Line Items]
Ownership percentage	100.00%
Corporate Joint Venture \| Doosan-PSI, LLC
Related Party Transaction [Line Items]
Investment amount with related party					$ 1,000
Percent of noncontrolling interest					50.00%
Return of investment in joint venture		$ 2,200