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SUBSEQUENT EVENTS (Details) - Colombia Subsidiary [Member] $ in Millions | 2 Months Ended
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Dec. 31, 2017 USD ($) contract
Scenario, Forecast [Member] |
Subsequent Event [Line Items] |
Number of forward exchange contracts | contract | 5
Subsequent Event [Member] |
Subsequent Event [Line Items] |
Forward exchange contract settlement amount expected in the future | $ | $ 5.0

X
- Definition Derivative Asset, Notional Future Amount To Be Settled + References No definition available. + Details
Name: | psmt_DerivativeAssetNotionalFutureAmountToBeSettled
Namespace Prefix: | psmt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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- Definition Derivative, Number Of Contracts + References No definition available. + Details
Name: | psmt_DerivativeNumberOfContracts
Namespace Prefix: | psmt_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event. + References No definition available. + Details
Name: | us-gaap_SubsequentEventLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | dei_LegalEntityAxis=psmt_ColumbiaSubsidiaryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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