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PROFIT SHARING PLAN (Details) (USD $) | 12 Months Ended
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Dec. 31, 2012 Age Period | Dec. 31, 2011 | Dec. 31, 2010
PROFIT SHARING PLAN [Abstract] |  |  |
Minimum age for full time employees to participate in the plan | 18 |  |
Number of yearly open periods for enrollment | 2 |  |
Maximum percentage of employees contribution towards plan (in hundredths) | 100.00% |  |
Employers contribution vesting period | 5 years |  |
Employer matching contribution, maximum (in hundredths) | 25.00% |  |
Employer contribution, amount | $ 348,000 | $ 432,000 | $ 431,000

X
- Definition Amount of matching contributions made by an employer to a defined contribution plan. + References No definition available. + Details
Name: | pesi_DefinedContributionPlanContributionByEmployer
Namespace Prefix: | pesi_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Refers to vesting period of employers contribution. + References No definition available. + Details
Name: | pesi_EmployersContributionVestingPeriod
Namespace Prefix: | pesi_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Refers to maximum percentage of pretax contribution of employees towards plan. + References No definition available. + Details
Name: | pesi_MaximumPercentageOfEmployeesContributionTowardsPlan
Namespace Prefix: | pesi_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Refers to minimum age for full time employees to participate in the plan. + References No definition available. + Details
Name: | pesi_MinimumAgeForFullTimeEmployeesToParticipateInPlan
Namespace Prefix: | pesi_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of yearly open periods for enrollment in the Company's 401(k) Plan. + References No definition available. + Details
Name: | pesi_NumberOfYearlyOpenPeriodsForEnrollment
Namespace Prefix: | pesi_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | pesi_ProfitSharingPlanAbstract
Namespace Prefix: | pesi_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerMatchingContributionPercent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration