Commitments and Contingencies (Narrative) (Details)	9 Months Ended
Sep. 30, 2013 sqft
Commitments and Contingencies Disclosure [Abstract]
Office Space	1,954

Office area covered under operating lease agreement.

No definition available.

Name:	ljpc_OfficeAreaCoveredUnderOperatingLeaseAgreement
Namespace Prefix:	ljpc_
Data Type:	num:areaItemType
Balance Type:	na
Period Type:	duration