SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Exit or Disposal Cost Obligations) (Narrative) (Details) - USD ($)	3 Months Ended	12 Months Ended
May 31, 2017	Aug. 31, 2018	Aug. 31, 2017
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES [Abstract]
Exit obligation, Other long-term liabilities	$ 496,000
Current exit obligation		$ 0
Exit obligation, Warehouse expenses		$ 1,000,000	$ 1,400,000

Disposal Group, Business Exit Obligation, Other Long-Term Liabilities

No definition available.

Name:	psmt_DisposalGroupBusinessExitObligationOtherLongTermLiabilities
Namespace Prefix:	psmt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration