Subsequent Events - Additional Information (Detail) (USD $)	12 Months Ended
Dec. 31, 2014
Subsequent Event [Line Items]
Supply Agreement Consideration To Be Paid In Stages	$ 650,000

Represents consideration to be paid in various stages with respect to supply agreement with its drug product manufacturer.

No definition available.

Name:	bpth_SupplyAgreementConsiderationToBePaidInStages
Namespace Prefix:	bpth_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration