Subsequent Events - Additional Information (Detail) (USD $)	3 Months Ended
Mar. 31, 2015
Subsequent Event [Line Items]
Supply Agreement Consideration To Be Paid In Stages	$ 430,000
Payments For Project Fees	$ 440,000bpth_PaymentsForProjectFees

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