XML 41 R31.htm IDEA: XBRL DOCUMENT v3.20.2

Revenue Recognition - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
Revenue Recognition [Abstract]
Development revenue and related costs	$ 0.2	$ 0.3

X

- Definition

Development revenue and related costs.

+ References

No definition available.

+ Details

Name:	pstv_DevelopmentRevenueAndRelatedCosts
Namespace Prefix:	pstv_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- References

No definition available.

+ Details

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