| Note 5 - Goodwill and Other Intangible Assets (Details) (USD $)
 | 12 Months Ended | 0 Months Ended | 3 Months Ended | 
| Dec. 31, 2014 | Dec. 31, 2013 | Oct. 01, 2014 | Oct. 01, 2013 | Jul. 29, 2014 | Sep. 30, 2014 | 
| Note 5 - Goodwill and Other Intangible Assets (Details) [Line Items] |  |  |  |  |  |  | 
| Goodwill, Impairment Loss | $ 380,000us-gaap_GoodwillImpairmentLoss | $ 27,856,000us-gaap_GoodwillImpairmentLoss |  |  |  |  | 
| Finite-Lived Intangible Assets, Net | 1,967,000us-gaap_FiniteLivedIntangibleAssetsNet |  |  |  |  |  | 
| Amortization of Intangible Assets | 638,000us-gaap_AmortizationOfIntangibleAssets | 745,000us-gaap_AmortizationOfIntangibleAssets |  |  |  |  | 
| SEC [Member] | Services [Member] |  |  |  |  |  |  | 
| Note 5 - Goodwill and Other Intangible Assets (Details) [Line Items] |  |  |  |  |  |  | 
| Goodwill, Impairment Loss |  | 13,016,000us-gaap_GoodwillImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis
 = pesi_ServicesMember
 / us-gaap_SubsegmentsAxis
 = pesi_SECMember
 |  |  |  |  | 
| CH Plateau Remediation Company [Member] | Services [Member] |  |  |  |  |  |  | 
| Note 5 - Goodwill and Other Intangible Assets (Details) [Line Items] |  |  |  |  |  |  | 
| Goodwill, Impairment Loss |  | 1,149,000us-gaap_GoodwillImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis
 = pesi_ServicesMember
 / us-gaap_SubsegmentsAxis
 = pesi_CHPlateauRemediationCompanyMember
 |  |  |  |  | 
| Treatment [Member] |  |  |  |  |  |  | 
| Note 5 - Goodwill and Other Intangible Assets (Details) [Line Items] |  |  |  |  |  |  | 
| Goodwill, Impairment Loss |  | 13,691,000us-gaap_GoodwillImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis
 = pesi_TreatmentMember
 | 0us-gaap_GoodwillImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis
 = pesi_TreatmentMember
 | 0us-gaap_GoodwillImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis
 = pesi_TreatmentMember
 |  |  | 
| Services [Member] | SYA [Member] |  |  |  |  |  |  | 
| Note 5 - Goodwill and Other Intangible Assets (Details) [Line Items] |  |  |  |  |  |  | 
| Goodwill, Impairment Loss |  |  |  |  | 380,000us-gaap_GoodwillImpairmentLoss / dei_LegalEntityAxis
 = pesi_SYAMember
 / us-gaap_StatementBusinessSegmentsAxis
 = pesi_ServicesMember
 |  | 
| Services [Member] |  |  |  |  |  |  | 
| Note 5 - Goodwill and Other Intangible Assets (Details) [Line Items] |  |  |  |  |  |  | 
| Goodwill, Impairment Loss | 380,000us-gaap_GoodwillImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis
 = pesi_ServicesMember
 | 14,165,000us-gaap_GoodwillImpairmentLoss / us-gaap_StatementBusinessSegmentsAxis
 = pesi_ServicesMember
 |  |  |  |  | 
| PCB Permit [Member] |  |  |  |  |  |  | 
| Note 5 - Goodwill and Other Intangible Assets (Details) [Line Items] |  |  |  |  |  |  | 
| Number Of Definte-Lived Permits | 1pesi_NumberOfDefiniteLivedPermits / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
 = pesi_PCBPermitMember
 |  |  |  |  |  | 
| Finite-Lived Intangible Asset, Useful Life | 10 years |  |  |  |  |  | 
| Finite-Lived Intangible Assets, Net | 227,000us-gaap_FiniteLivedIntangibleAssetsNet / us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis
 = pesi_PCBPermitMember
 |  |  |  |  |  | 
| SYA [Member] |  |  |  |  |  |  | 
| Note 5 - Goodwill and Other Intangible Assets (Details) [Line Items] |  |  |  |  |  |  | 
| Goodwill, Impairment Loss |  |  |  |  | $ 380,000us-gaap_GoodwillImpairmentLoss / dei_LegalEntityAxis
 = pesi_SYAMember
 | $ 380,000us-gaap_GoodwillImpairmentLoss / dei_LegalEntityAxis
 = pesi_SYAMember
 |