Note 4 - Revenue Recognition (Details Textual)	3 Months Ended	9 Months Ended
Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Percent of Revenue from Contract With Customer, Including Assessed Tax	100.00%	100.00%	100.00%	100.00%
Costs Incurred for Uncompleted Contracts, Anticipated Collection Period			1 year
Specialty Piping Systems And Coating [Member]
Percent of Revenue from Contract With Customer, Including Assessed Tax			90.00%

Represents the duration of time within which costs incurred for uncompleted contracts are anticipated to be collected.

No definition available.

Name:	ppih_CostsIncurredForUncompletedContractsAnticipatedCollectionPeriod
Namespace Prefix:	ppih_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration