XML 49 R39.htm IDEA: XBRL DOCUMENT v3.21.2

Basis of Presentation (Additional Information) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2021 USD ($)
Disclosure Text Block [Abstract]
Bank service fees	$ 4

X

- Definition

Bank service fees.

+ References

No definition available.

+ Details

Name:	per_BankServiceFees
Namespace Prefix:	per_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- References

No definition available.

+ Details

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