Debt Instrument, Extension Fee

No definition available.

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Period Type:	duration

- Definition

Line of Credit Facility, Expiration Period Prior To Final Maturity Of Senior Notes

+ References

No definition available.

+ Details

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Namespace Prefix:	psix_
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Balance Type:	na
Period Type:	duration

- Definition

Number Of Board Members

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Research And Development Expense (Excluding Engineering)

+ References

No definition available.

+ Details

Name:	psix_ResearchAndDevelopmentExpenseExcludingEngineering
Namespace Prefix:	psix_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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

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- Definition

The amount recovered from insurance. These recoveries reduce costs and losses that are reported as a separate line item under operating expenses.

+ 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 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

+ Details

Name:	us-gaap_InsuranceRecoveries
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ 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 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

+ References

No definition available.

+ Details

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- Definition

Cash received on stock transaction after deduction of issuance costs.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=psix_SharePurchaseAgreementWeichaiTransactionMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=psix_StandardCharteredBankCreditAgreementMember
Namespace Prefix:
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Summary of Significant Accounting Policies and Other Information - Narrative (Details)		1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Apr. 02, 2020 USD ($)	Mar. 31, 2017 USD ($)	Sep. 30, 2019 USD ($) board_member	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) board_member segment	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Concentration Risk [Line Items]
Number of board members \| board_member			3		3
Number of operating segments \| segment					1
Research and development and engineering expenses			$ 5,900,000	$ 7,300,000	$ 17,400,000	$ 19,400,000
Litigation reserves					$ 9,900,000		$ 16,000,000
Share Purchase Agreement, Weichai Transaction
Concentration Risk [Line Items]
Consideration received on transaction		$ 60,000,000
Revolving Credit Facility \| Subsequent Event \| Standard Chartered Bank Credit Agreement
Concentration Risk [Line Items]
Borrowing amount	$ 130,000,000
Maturity period prior to the final maturity	60 days
Extension fee percentage	0.25%