Summary of Significant Accounting Policies	9 Months Ended
Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies During the three and nine months ended September 30, 2017, there have been no changes to the Company’s significant accounting policies as described in the Annual Report on Form 10-K for the fiscal year ended December 31, 2016. Basis of Presentation and Use of Estimates The accompanying unaudited condensed consolidated financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information and with the instructions to Form 10-Q and Article 10 of the SEC Regulation S-X. Accordingly, they should be read in conjunction with the audited financial statements and notes thereto for the year ended December 31, 2016 included in the Company’s Annual Report on Form 10-K filed with the SEC on February 23, 2017. The accompanying unaudited condensed consolidated financial statements include the accounts of La Jolla Pharmaceutical Company and its wholly-owned subsidiaries. All significant inter-company transactions and balances have been eliminated in consolidation. The unaudited condensed consolidated financial statements contain all normal recurring accruals and adjustments that, in the opinion of management, are necessary to present fairly the condensed consolidated balance sheet of the Company at September 30, 2017, the condensed consolidated statement of operations for the three and nine months ended September 30, 2017 and the condensed consolidated statement of cash flows for the nine months ended September 30, 2017. Estimates were made relating to useful lives of fixed assets, valuation allowances, impairment of assets, share-based compensation expense and accruals for clinical studies and research and development expenses. Actual results could differ materially from those estimates. Certain amounts previously reported in the financial statements have been reclassified to conform to the current presentation. Such reclassifications did not affect net loss, shareholders’ equity or cash flows. The results of operations for the three and nine months ended September 30, 2017 are not necessarily indicative of the results to be expected for the full year or any future interim periods. The accompanying condensed consolidated balance sheet at December 31, 2016 has been derived from the audited consolidated balance sheet at December 31, 2016 contained in the above referenced Form 10-K. Comprehensive Loss Comprehensive loss for the periods reported was comprised solely of the Company’s net loss. The comprehensive loss for the three and nine months ended September 30, 2017 was $26.3 million and $76.3 million, respectively, and for the three and nine months ended September 30, 2016 was $21.3 million and $53.3 million, respectively. There were no other changes in equity that were excluded from net loss for all periods presented. Net Loss per Share Basic net loss per share is calculated based on the weighted-average number of common shares outstanding, excluding unvested restricted stock awards. Diluted net loss per share is calculated using the weighted-average number of common shares outstanding plus common stock equivalents. Convertible preferred stock, stock options, warrants and unvested restricted stock awards are considered common stock equivalents and are included in the calculation of diluted net loss per share using the treasury stock method when their effect is dilutive. Common stock equivalents are excluded from the calculation of diluted net loss per share when their effect is anti-dilutive. As of September 30, 2017 and 2016, there were common stock equivalents of 11.9 million shares and 11.2 million shares, respectively, which were excluded from the calculation of diluted net loss per share because they were anti-dilutive. Recent Accounting Pronouncements In May 2017, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) 2017-09, Compensation - Stock Compensation (Topic 718), Scope of Modification Accounting. The new standard clarifies when to account for a change to the terms or conditions of a share-based payment award as a modification. ASU 2017-09 will be effective for the Company in the first quarter of 2018. Early adoption is permitted, including adoption in an interim period for which financial statements have not yet been issued. The Company plans to adopt the ASU in the first quarter of 2018 and expects the standard to have no material impact on the Company’s financial position or results of operations. In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The new standard update clarifies the presentation of restricted cash and cash equivalents, and requires companies to include restricted cash and cash equivalents in the beginning and ending cash and cash equivalents on the statement of cash flows. Additional disclosures will be required to describe the amount and detail of the restriction by balance sheet line item. ASU 2016-18 will be effective for the Company in the first quarter of 2018. Early adoption is permitted, including adoption in an interim period using a retrospective transition method to each period presented. The Company plans to adopt the ASU in the first quarter of 2018. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). The new standard requires lessees to recognize most leases on their balance sheets as lease liabilities with corresponding right-of-use assets and eliminates certain real estate-specific provisions. ASU 2016-02 will be effective for the Company in the first quarter of 2019 and will be adopted on a modified retrospective transition basis for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The Company currently plans to implement ASU 2016-02 in the first quarter of 2019. By 2019, all of the Company’s active existing leases will have ended. Those leases will not have an impact on the consolidated financial statements upon adoption in 2019, and there will be no requirement for modified retrospective application to the years prior to adoption. In December 2016, the Company entered into a 10-year lease agreement for its corporate headquarters. The expected lease commencement date is November 1, 2017. Upon adoption of ASU 2016-02, this lease will be recognized on the balance sheet as a lease liability with a corresponding right-of-use asset, which would require modified retrospective application upon adoption in 2019 back to the fourth quarter of 2017. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). The new standard is based on the principle that revenue should be recognized to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Since its initial release, the FASB has issued several amendments to the standard, which include clarification of accounting guidance related to identification of performance obligations and principal versus agent considerations. Topic 606 will be effective for the Company in the first quarter of 2018 and allows for full retrospective or a modified retrospective adoption approach. We currently do not have any products or revenues from customers. Accordingly, the adoption of this standard will not have a material impact on the Company’s financial position or results of operations. The Company plans to implement the requirements prospectively upon recognition of the first revenue from customers, and there will not be any retrospective impact to our financial statements. The Contract Revenue - Related Party reported in our results of operations for 2015 and 2016, which represents expense reimbursements from a related party, will not be impacted by the adoption of the new guidance.

Summary of Significant Accounting Policies

During the three and nine months ended September 30, 2017, there have been no changes to the Company’s significant accounting policies as described in the Annual Report on Form 10-K for the fiscal year ended December 31, 2016.

Basis of Presentation and Use of Estimates

The accompanying unaudited condensed consolidated financial statements of the Company have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information and with the instructions to Form 10-Q and Article 10 of the SEC Regulation S-X. Accordingly, they should be read in conjunction with the audited financial statements and notes thereto for the year ended December 31, 2016 included in the Company’s Annual Report on Form 10-K filed with the SEC on February 23, 2017. The accompanying unaudited condensed consolidated financial statements include the accounts of La Jolla Pharmaceutical Company and its wholly-owned subsidiaries. All significant inter-company transactions and balances have been eliminated in consolidation. The unaudited condensed consolidated financial statements contain all normal recurring accruals and adjustments that, in the opinion of management, are necessary to present fairly the condensed consolidated balance sheet of the Company at September 30, 2017, the condensed consolidated statement of operations for the three and nine months ended September 30, 2017 and the condensed consolidated statement of cash flows for the nine months ended September 30, 2017. Estimates were made relating to useful lives of fixed assets, valuation allowances, impairment of assets, share-based compensation expense and accruals for clinical studies and research and development expenses. Actual results could differ materially from those estimates. Certain amounts previously reported in the financial statements have been reclassified to conform to the current presentation. Such reclassifications did not affect net loss, shareholders’ equity or cash flows. The results of operations for the three and nine months ended September 30, 2017 are not necessarily indicative of the results to be expected for the full year or any future interim periods. The accompanying condensed consolidated balance sheet at December 31, 2016 has been derived from the audited consolidated balance sheet at December 31, 2016 contained in the above referenced Form 10-K.

Comprehensive Loss

Comprehensive loss for the periods reported was comprised solely of the Company’s net loss. The comprehensive loss for the three and nine months ended September 30, 2017 was $26.3 million and $76.3 million, respectively, and for the three and nine months ended September 30, 2016 was $21.3 million and $53.3 million, respectively. There were no other changes in equity that were excluded from net loss for all periods presented.

Net Loss per Share

Basic net loss per share is calculated based on the weighted-average number of common shares outstanding, excluding unvested restricted stock awards. Diluted net loss per share is calculated using the weighted-average number of common shares outstanding plus common stock equivalents. Convertible preferred stock, stock options, warrants and unvested restricted stock awards are considered common stock equivalents and are included in the calculation of diluted net loss per share using the treasury stock method when their effect is dilutive. Common stock equivalents are excluded from the calculation of diluted net loss per share when their effect is anti-dilutive. As of September 30, 2017 and 2016, there were common stock equivalents of 11.9 million shares and 11.2 million shares, respectively, which were excluded from the calculation of diluted net loss per share because they were anti-dilutive.

Recent Accounting Pronouncements

In May 2017, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update (ASU) 2017-09, Compensation - Stock Compensation (Topic 718), Scope of Modification Accounting. The new standard clarifies when to account for a change to the terms or conditions of a share-based payment award as a modification. ASU 2017-09 will be effective for the Company in the first quarter of 2018. Early adoption is permitted, including adoption in an interim period for which financial statements have not yet been issued. The Company plans to adopt the ASU in the first quarter of 2018 and expects the standard to have no material impact on the Company’s financial position or results of operations.

In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The new standard update clarifies the presentation of restricted cash and cash equivalents, and requires companies to include restricted cash and cash equivalents in the beginning and ending cash and cash equivalents on the statement of cash flows. Additional disclosures will be required to describe the amount and detail of the restriction by balance sheet line item. ASU 2016-18 will be effective for the Company in the first quarter of 2018. Early adoption is permitted, including adoption in an interim period using a retrospective transition method to each period presented. The Company plans to adopt the ASU in the first quarter of 2018.

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). The new standard requires lessees to recognize most leases on their balance sheets as lease liabilities with corresponding right-of-use assets and eliminates certain real estate-specific provisions. ASU 2016-02 will be effective for the Company in the first quarter of 2019 and will be adopted on a modified retrospective transition basis for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The Company currently plans to implement ASU 2016-02 in the first quarter of 2019. By 2019, all of the Company’s active existing leases will have ended. Those leases will not have an impact on the consolidated financial statements upon adoption in 2019, and there will be no requirement for modified retrospective application to the years prior to adoption. In December 2016, the Company entered into a 10-year lease agreement for its corporate headquarters. The expected lease commencement date is November 1, 2017. Upon adoption of ASU 2016-02, this lease will be recognized on the balance sheet as a lease liability with a corresponding right-of-use asset, which would require modified retrospective application upon adoption in 2019 back to the fourth quarter of 2017.

In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). The new standard is based on the principle that revenue should be recognized to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Since its initial release, the FASB has issued several amendments to the standard, which include clarification of accounting guidance related to identification of performance obligations and principal versus agent considerations. Topic 606 will be effective for the Company in the first quarter of 2018 and allows for full retrospective or a modified retrospective adoption approach. We currently do not have any products or revenues from customers. Accordingly, the adoption of this standard will not have a material impact on the Company’s financial position or results of operations. The Company plans to implement the requirements prospectively upon recognition of the first revenue from customers, and there will not be any retrospective impact to our financial statements. The Contract Revenue - Related Party reported in our results of operations for 2015 and 2016, which represents expense reimbursements from a related party, will not be impacted by the adoption of the new guidance.