Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2021	Apr. 15, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K/A
Amendment Flag	true
Amendment Description	This Amendment No. 1 on Form 10-K/A (this “Amendment”) amends the Annual Report on Form 10-K of La Jolla Pharmaceutical Company (the “Company” or “La Jolla”) for the year ended December 31, 2021, originally filed with the U.S. Securities and Exchange Commission (the “SEC”) on March 9, 2022 (the “Original Filing”). This Amendment is being filed for the purpose of providing the information required by Items 10 through 14 of Part III of the Annual Report on Form 10-K. This information was previously omitted from the Original Filing in reliance on General Instruction G(3) to the Annual Report on Form 10-K, which permits the above-referenced Items to be incorporated in the Annual Report on Form 10-K by reference from a definitive proxy statement, if such definitive proxy statement is filed no later than 120 days after December 31, 2021. At this time, La Jolla is filing this Amendment to include Part III information in its Annual Report on Form 10-K because La Jolla does not intend to file its definitive proxy statement within 120 days of December 31, 2021. In accordance with Rule 12b-15 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), Items 10 through 14 of Part III of the Original Filing are hereby amended and restated in their entirety. In addition, this Form 10-K/A amends and restates in its entirety Item 15 of Part IV of the Original Filing to include new certifications by our principal executive officer and principal financial and accounting officer under Section 302 of the Sarbanes-Oxley Act of 2002, pursuant to Rule 12b-15 under the Exchange Act. Because no financial statements have been included in this Amendment and this Amendment does not contain or amend any disclosure with respect to Items 307 and 308 of Regulation S-K, paragraphs 3, 4 and 5 of such certifications have been omitted. We are not including the certifications under Section 906 of the Sarbanes-Oxley Act of 2002 as no financial statements are being filed with this Amendment. Except as described above, no other changes have been made to the Original Filing. Except as otherwise indicated herein, this Amendment continues to speak as of the date of the Original Filing, and La Jolla has not updated the disclosures contained therein to reflect any events that occurred subsequent to the date of the Original Filing. The disclosures contained in the Original Filing and in the documents incorporated therein by reference are provided as of the date of such disclosures.
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity File Number	1-36282
Entity Registrant Name	LA JOLLA PHARMACEUTICAL COMPANY
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	33-0361285
Entity Address, Address Line One	201 Jones Road
Entity Address, Address Line Two	Suite 400
Entity Address, City or Town	Waltham
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02451
City Area Code	617
Local Phone Number	715-3600
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	LJPC
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		25,621,657
Entity Central Index Key	0000920465
Entity Public Float			$ 73.3
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
ICFR Auditor Attestation Flag	false
Auditor Name	Baker Tilly US, LLP
Auditor Location	San Diego, California
Auditor Firm ID	23
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE None.

LA JOLLA PHARMACEUTICAL CO 10-K/A