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Commitments and Contingencies (Narrative) (Details) (USD $) | Dec. 31, 2014
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Guarantee Obligations [Line Items] |
Additional bonding capacity | $ 288,100,000 powl_CommitmentsAndContingenciesAdditionalBondingCapacity
Powell (UK) Limited |
Guarantee Obligations [Line Items] |
Guarantee liability | 3,900,000 us-gaap_GuaranteeObligationsCurrentCarryingValue / dei_LegalEntityAxis = powl_PowellUKLimitedMember
Revolving credit facility | 15,500,000 us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity / dei_LegalEntityAxis = powl_PowellUKLimitedMember
Amount of credit facility remaining borrowing capacity | 11,600,000 us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity / dei_LegalEntityAxis = powl_PowellUKLimitedMember
Financial Standby Letter of Credit |
Guarantee Obligations [Line Items] |
Guarantee liability | 18,300,000 us-gaap_GuaranteeObligationsCurrentCarryingValue / us-gaap_GuaranteeObligationsByNatureAxis = us-gaap_FinancialStandbyLetterOfCreditMember
Performance Guarantee |
Guarantee Obligations [Line Items] |
Guarantee liability | $ 311,900,000 us-gaap_GuaranteeObligationsCurrentCarryingValue / us-gaap_GuaranteeObligationsByNatureAxis = us-gaap_PerformanceGuaranteeMember

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- Definition Commitments and contingencies additional bonding capacity. + References No definition available. + Details
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- Definition The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 460 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248 + Details
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- 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://www.xbrl.org/2003/role/presentationRef -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 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 + Details
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- Definition Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 + Details
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