Cover Page - shares	6 Months Ended
	Jun. 30, 2020	Jul. 27, 2020
Document And Entity Information [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	1-36282
Entity Registrant Name	LA JOLLA PHARMACEUTICAL COMPANY
Entity Incorporation, State or Country Code	CA
Entity Tax Identification Number	33-0361285
Entity Address, Address Line One	4550 Towne Centre Court,
Entity Address, City or Town	San Diego,
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	207-4264
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	LJPC
Security Exchange Name	NASDAQ
Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Shell Company	false
Entity Common Stock, Shares Outstanding		27,362,100
Entity Central Index Key	0000920465
Document Period End Date	Jun. 30, 2020
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31