Commitments and Contingencies (Narrative) (Details)	3 Months Ended
Mar. 31, 2014 sqft
Commitments and Contingencies Disclosure [Abstract]
Office Space	1,795

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