Deferred Royalty Obligations

No definition available.

Name:	ljpc_DeferredRoyaltyObligations
Namespace Prefix:	ljpc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Royalty Agreement, Amount Funded

+ References

No definition available.

+ Details

Name:	ljpc_RoyaltyAgreementAmountFunded
Namespace Prefix:	ljpc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Royalty Agreement, Increase In Maximum Potential Payout, Percent

+ References

No definition available.

+ Details

Name:	ljpc_RoyaltyAgreementIncreaseInMaximumPotentialPayoutPercent
Namespace Prefix:	ljpc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Royalty Agreement, Maximum Potential Payout, Percent

+ References

No definition available.

+ Details

Name:	ljpc_RoyaltyAgreementMaximumPotentialPayoutPercent
Namespace Prefix:	ljpc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Royalty Agreement, Required Payment For Breach Of Agreement, Payment One

+ References

No definition available.

+ Details

Name:	ljpc_RoyaltyAgreementRequiredPaymentForBreachOfAgreementPaymentOne
Namespace Prefix:	ljpc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Royalty Agreement, Required Payment For Breach Of Agreement, Payment Two

+ References

No definition available.

+ Details

Name:	ljpc_RoyaltyAgreementRequiredPaymentForBreachOfAgreementPaymentTwo
Namespace Prefix:	ljpc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Royalty Obligation Payable

+ References

No definition available.

+ Details

Name:	ljpc_RoyaltyObligationPayable
Namespace Prefix:	ljpc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after accumulated amortization, of debt discount.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentUnamortizedDiscount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

+ Details

Name:	us-gaap_DeferredFinanceCostsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Sum of the carrying values as of the balance sheet date of (a) interest payable on all forms of debt, including trade payables, that has been incurred, and (b) dividends declared but unpaid on equity securities issued by the entity and outstanding (also includes dividends collected on behalf of another owner of securities that are being held by the entity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.15(a))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.15(5))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_InterestAndDividendsPayableCurrentAndNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Aggregate amount of interest expense on all borrowings.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.7,8)
-URI http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260

+ Details

Name:	us-gaap_InterestExpenseBorrowings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3291-108585

+ Details

Name:	us-gaap_RepaymentsOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	srt_CounterpartyNameAxis=ljpc_HealthCareRoyaltyPartnersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=ljpc_RoyaltyFinancingAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LoansPayableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_OtherNoncurrentLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ljpc_RoyaltyAgreementPayoutPeriodAxis=ljpc_RoyaltyAgreementPayoutPeriodOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ljpc_RoyaltyAgreementPayoutPeriodAxis=ljpc_RoyaltyAgreementPayoutPeriodTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ljpc_RoyaltyAgreementPayoutPeriodAxis=ljpc_RoyaltyAgreementPayoutPeriodThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Deferred Royalty Obligation - Additional Information (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	May 10, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Debt Instrument [Line Items]
Deferred royalty obligation, net		$ 124,421		$ 124,421		$ 124,379
Interest expense		2,500	$ 2,800	7,400	$ 8,400
Royalty Obligation Payable		700		700
HealthCare Royalty Partners
Debt Instrument [Line Items]
Proceeds from royalty agreement	$ 125,000
Required payment for breach of agreement, payment two	225,000
Required payment for breach of agreement, payment one	125,000
HealthCare Royalty Partners \| Royalty Financing Agreement \| Loans Payable
Debt Instrument [Line Items]
Deferred royalty obligation, net	125,000	124,400		124,400
Debt issuance costs	$ 700
Unamortized debt discount		600		600
Accrued interest expense		20,800		20,800		15,500
Royalty payments		600		2,100
HealthCare Royalty Partners \| Royalty Financing Agreement \| Loans Payable \| Other Noncurrent Liabilities
Debt Instrument [Line Items]
Accrued interest expense		$ 16,900		$ 16,900		$ 12,800
HealthCare Royalty Partners \| Period One
Debt Instrument [Line Items]
Maximum potential royalty payout	10.00%
HealthCare Royalty Partners \| Period Two
Debt Instrument [Line Items]
Increase in maximum potential payout percent	4.00%
HealthCare Royalty Partners \| Payout Period
Debt Instrument [Line Items]
Increase in maximum potential payout percent	4.00%