Debt Instrument, Borrowing Reserve

No definition available.

Name:	psix_DebtInstrumentBorrowingReserve
Namespace Prefix:	psix_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	psix_LineofCreditFacilityExpirationPeriodPriorToFinalMaturityOfSeniorNotes
Namespace Prefix:	psix_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the fee that accompanies borrowing money under the debt instrument.

+ References

+ Details

Name:	us-gaap_DebtInstrumentFeeAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ 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 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

+ Details

Name:	us-gaap_DeferredFinanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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

Name:	us-gaap_LineOfCreditFacilityLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
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

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DebtInstrumentAxis=psix_WellsFargoCreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_PrimeRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
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Data Type:	na
Balance Type:
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- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
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Debt - Wells Fargo Credit Agreement - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Mar. 29, 2018	Dec. 31, 2017	Oct. 03, 2017	Jul. 17, 2017	Mar. 31, 2017	Jun. 28, 2016
Line of Credit Facility [Line Items]
Debt issuance costs	$ 1,000,000		$ 900,000
Wells Fargo Credit Agreement
Line of Credit Facility [Line Items]
Lender fees		$ 800,000				$ 700,000
Revolving Credit Facility \| Wells Fargo Credit Agreement
Line of Credit Facility [Line Items]
Maximum borrowing capacity	75,000,000	$ 75,000,000		$ 58,750,000.00	$ 52,500,000.0	65,000,000	$ 75,000,000
Reserve against borrowing base availability	$ 9,000,000
Unused line fee percentage	0.25%
Available revolving line of credit balance	$ 8,900,000		13,000,000			$ 40,000,000.0
Debt issuance costs	0		100,000
Lender fees	$ 800,000		$ 700,000
Revolving Credit Facility \| Wells Fargo Credit Agreement \| Minimum \| Prime Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.25%
Revolving Credit Facility \| Wells Fargo Credit Agreement \| Minimum \| LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate	2.75%
Revolving Credit Facility \| Wells Fargo Credit Agreement \| Maximum \| Prime Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.75%
Revolving Credit Facility \| Wells Fargo Credit Agreement \| Maximum \| LIBOR
Line of Credit Facility [Line Items]
Basis spread on variable rate	3.25%
Revolving Credit Facility
Line of Credit Facility [Line Items]
Maturity period prior to the final maturity of unsecured senior notes	60 days
Debt instrument, interest rate	1.00%