LEASES (Summary of Rental Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2016
LEASES [Abstract]
Minimum rental payments	$ 12,963	$ 11,223	$ 9,986
Deferred rent accurals	127	(80)	1,363
Total straight line rent expense	13,090	11,143	11,349
Contingent rental payments	3,399	3,320	3,208
Common area maintenance expense	723	1,174	1,369
Rental expense	$ 17,212	$ 15,637	$ 15,926

Represents the payments that the lessee is obligated to pay for the common area maintenance to the landlord.

No definition available.

Name:	psmt_OperatingLeasesRentExpenseCommonAreaMaintenanceExpense
Namespace Prefix:	psmt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the difference between the straight-line expense and the cash payments of the lease.

+ References

No definition available.

+ Details

Name:	psmt_OperatingLeasesRentExpenseDeferredRentAccurals
Namespace Prefix:	psmt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the straight line expense of the lease

+ References

No definition available.

+ Details

Name:	psmt_OperatingLeasesRentExpenseStraightLineRentExpense
Namespace Prefix:	psmt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_LeasesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The increases or decreases in lease payments that result from changes occurring after the inception of the lease in the factors (other than the passage of time) on which lease payments are based, except that any escalation of minimum lease payments relating to increases in construction or acquisition cost of the leased property or for increases in some measure of cost or value during the construction or preconstruction period, are excluded from contingent rentals. Contingent rentals also may include amounts for which the triggering events have not yet occurred or the specified targets for which have not yet been achieved (such as sales based percentage rent), but which events are considered probable of occurring or which specified targets are considered probable of being achieved.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77902758&loc=d3e41499-112717

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 55
-Paragraph 40
-Subparagraph (Note 3)
-URI http://asc.fasb.org/extlink&oid=82846649&loc=d3e38371-112697

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 40
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77895616&loc=d3e36728-112689

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 25
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=77910666&loc=d3e35050-112683

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=84164451&loc=d3e36991-112694

+ Details

Name:	us-gaap_OperatingLeasesRentExpenseContingentRentals
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This element represents the payments that the lessee is obligated to make or can be required to make in connection with a property under the terms of an agreement classified as an operating lease, excluding contingent rentals and a guarantee by the lessee of the lessor's debt and the lessee's obligation to pay (apart from the rental payments) executory costs such as insurance, maintenance, and taxes.

+ References

+ Details

Name:	us-gaap_OperatingLeasesRentExpenseMinimumRentals
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

+ References

+ Details

Name:	us-gaap_OperatingLeasesRentExpenseNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration