Summary of Significant Accounting Policies	3 Months Ended
Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies During the three months ended March 31, 2018, there have been no changes to the Company’s significant accounting policies as described in the Annual Report on Form 10-K for the year ended December 31, 2017, except as described below. 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 consolidated financial statements and notes thereto for the year ended December 31, 2017 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, filed with the SEC on February 22, 2018. 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 March 31, 2018, the condensed consolidated statement of operations for the three months ended March 31, 2018 and the condensed consolidated statement of cash flows for the three months ended March 31, 2018. Estimates were made relating to useful lives of inventory, fixed assets, return and valuation allowances, impairment of assets, share-based compensation expense and accruals for clinical studies and research and development expense. 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 months ended March 31, 2018 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, 2017 has been derived from the audited consolidated balance sheet at December 31, 2017 contained in the above referenced Annual Report on Form 10-K. Inventory Inventory is stated at the lower of cost or estimated net realizable value, on a first-in, first-out (FIFO) basis. The Company periodically analyzes its inventory levels and writes down inventory as cost of product sales when: inventory has become obsolete; inventory has a cost basis in excess of its estimated net realizable value; or inventory quantities are in excess of expected sales. Revenue Recognition The Company adopted the Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 606 - Revenue from Contracts with Customers (ASC 606) at the time of its first commercial shipment of GIAPREZA in the first quarter of 2018. The Company had no revenue from product sales prior to the first quarter of 2018. Under ASC 606, the Company recognizes revenue when distributors (our customers) obtain control of the Company’s product, which typically occurs on delivery. Revenue is recognized in an amount that reflects the consideration that the Company expects to receive in exchange for those goods. To determine revenue recognition for contracts with customers within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. Revenue from product sales is recorded at the transaction price, net of estimates for variable consideration consisting of chargebacks, discounts, returns and other allowances offered to our customers. Variable consideration is estimated using the most-likely amount method, which is the single-most likely outcome under a contract and is typically at the stated contractual rate. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results vary materially from the Company’s estimates, the Company will adjust these estimates, which will affect revenue from product sales and earnings in the period such estimates are adjusted. Chargebacks. Chargebacks are discounts the Company provides to distributors in the event that the sales prices to end users are below the distributors’ price they acquire the product from the Company. The accrual for distributor chargebacks is estimated based on known chargeback rates. Estimates for chargebacks are recorded as a reduction of revenue and accounts receivable upon delivery to the Company’s customers. Discounts. The Company offers customers various forms of incentives and consideration, including prompt pay discounts, service fees and other contract fees. The Company estimates discounts and fees primarily based on contractual terms. These discounts and fees are recorded as a reduction of revenue and accounts receivable upon delivery to the Company’s customers. Returns. The Company offers customers a limited right of return, generally for damaged or expired product. To date, there have been no product returns. The Company estimates returns based on an analysis of comparable companies. The estimates for returns are recorded as a reduction of revenue and accounts receivable upon delivery to the Company’s customers. The Company will continue to assess its estimates of variable consideration as it accumulates additional historical data and will adjust these estimates accordingly. 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 based on 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 March 31, 2018 and 2017, there were 14.1 million shares and 11.4 million shares, respectively, of common stock equivalents, which were excluded from the calculation of diluted net loss per share because their effect was anti-dilutive. Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements In May 2017, the FASB issued Accounting Standard Update (ASU) 2017-09, Compensation - Stock Compensation (Topic 718), Scope of Modification Accounting. The standard clarifies when to account for a change in the terms or conditions of a share-based payment award as a modification. The standard is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2017. The Company adopted the standard in the first quarter of 2018. Adoption of the standard did not have a 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 standard clarifies the presentation of restricted cash and cash equivalents and requires companies to include restricted cash and cash equivalents in the beginning and ending balances of cash and cash equivalents on the statement of cash flows. The standard also requires additional disclosures to describe the amount and detail of the restriction by balance sheet line item. The standard is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2017. The Company adopted the standard in the first quarter of 2018. Accordingly, restricted cash is included as a component of cash, cash equivalents and restricted cash in the unaudited condensed consolidated statement of cash flows for all periods presented, and we have disclosed the amount and detail of the restriction by balance sheet line item. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). The 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. The Company adopted the standard in the first quarter of 2018. Refer to the revenue recognition disclosure above. Not Yet Adopted Accounting Pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). The 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 with modified retrospective application for the Company’s 10-year lease agreement for its corporate headquarters, which commenced October 30, 2017. This lease will be recognized on the balance sheet as a lease liability with a corresponding right-of-use asset, which will require modified retrospective application back to the fourth quarter of 2017 and for all of 2018. All of the Company’s other leases will have ended by the first quarter of 2019 and, therefore, will not require modified retrospective disclosures applied within the consolidated financial statements upon adoption of the standard.

Summary of Significant Accounting Policies

During the three months ended March 31, 2018, there have been no changes to the Company’s significant accounting policies as described in the Annual Report on Form 10-K for the year ended December 31, 2017, except as described below.

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 consolidated financial statements and notes thereto for the year ended December 31, 2017 included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, filed with the SEC on February 22, 2018. 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 March 31, 2018, the condensed consolidated statement of operations for the three months ended March 31, 2018 and the condensed consolidated statement of cash flows for the three months ended March 31, 2018. Estimates were made relating to useful lives of inventory, fixed assets, return and valuation allowances, impairment of assets, share-based compensation expense and accruals for clinical studies and research and development expense. 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 months ended March 31, 2018 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, 2017 has been derived from the audited consolidated balance sheet at December 31, 2017 contained in the above referenced Annual Report on Form 10-K.

Inventory

Inventory is stated at the lower of cost or estimated net realizable value, on a first-in, first-out (FIFO) basis. The Company periodically analyzes its inventory levels and writes down inventory as cost of product sales when: inventory has become obsolete; inventory has a cost basis in excess of its estimated net realizable value; or inventory quantities are in excess of expected sales.

Revenue Recognition

The Company adopted the Financial Accounting Standards Board (FASB) Accounting Standards Codification (ASC) Topic 606 - Revenue from Contracts with Customers (ASC 606) at the time of its first commercial shipment of GIAPREZA in the first quarter of 2018. The Company had no revenue from product sales prior to the first quarter of 2018.

Under ASC 606, the Company recognizes revenue when distributors (our customers) obtain control of the Company’s product, which typically occurs on delivery. Revenue is recognized in an amount that reflects the consideration that the Company expects to receive in exchange for those goods. To determine revenue recognition for contracts with customers within the scope of ASC 606, the Company performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation.

Revenue from product sales is recorded at the transaction price, net of estimates for variable consideration consisting of chargebacks, discounts, returns and other allowances offered to our customers. Variable consideration is estimated using the most-likely amount method, which is the single-most likely outcome under a contract and is typically at the stated contractual rate. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results vary materially from the Company’s estimates, the Company will adjust these estimates, which will affect revenue from product sales and earnings in the period such estimates are adjusted.

Chargebacks. Chargebacks are discounts the Company provides to distributors in the event that the sales prices to end users are below the distributors’ price they acquire the product from the Company. The accrual for distributor chargebacks is estimated based on known chargeback rates. Estimates for chargebacks are recorded as a reduction of revenue and accounts receivable upon delivery to the Company’s customers.

Discounts. The Company offers customers various forms of incentives and consideration, including prompt pay discounts, service fees and other contract fees. The Company estimates discounts and fees primarily based on contractual terms. These discounts and fees are recorded as a reduction of revenue and accounts receivable upon delivery to the Company’s customers.

Returns. The Company offers customers a limited right of return, generally for damaged or expired product. To date, there have been no product returns. The Company estimates returns based on an analysis of comparable companies. The estimates for returns are recorded as a reduction of revenue and accounts receivable upon delivery to the Company’s customers.

The Company will continue to assess its estimates of variable consideration as it accumulates additional historical data and will adjust these estimates accordingly.

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 based on 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 March 31, 2018 and 2017, there were 14.1 million shares and 11.4 million shares, respectively, of common stock equivalents, which were excluded from the calculation of diluted net loss per share because their effect was anti-dilutive.

Recent Accounting Pronouncements

Recently Adopted Accounting Pronouncements

In May 2017, the FASB issued Accounting Standard Update (ASU) 2017-09, Compensation - Stock Compensation (Topic 718), Scope of Modification Accounting. The standard clarifies when to account for a change in the terms or conditions of a share-based payment award as a modification. The standard is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2017. The Company adopted the standard in the first quarter of 2018. Adoption of the standard did not have a 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 standard clarifies the presentation of restricted cash and cash equivalents and requires companies to include restricted cash and cash equivalents in the beginning and ending balances of cash and cash equivalents on the statement of cash flows. The standard also requires additional disclosures to describe the amount and detail of the restriction by balance sheet line item. The standard is effective for annual periods, including interim periods within those annual periods, beginning after December 15, 2017. The Company adopted the standard in the first quarter of 2018. Accordingly, restricted cash is included as a component of cash, cash equivalents and restricted cash in the unaudited condensed consolidated statement of cash flows for all periods presented, and we have disclosed the amount and detail of the restriction by balance sheet line item.

In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). The 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. The Company adopted the standard in the first quarter of 2018. Refer to the revenue recognition disclosure above.

Not Yet Adopted Accounting Pronouncements

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). The 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 with modified retrospective application for the Company’s 10-year lease agreement for its corporate headquarters, which commenced October 30, 2017. This lease will be recognized on the balance sheet as a lease liability with a corresponding right-of-use asset, which will require modified retrospective application back to the fourth quarter of 2017 and for all of 2018. All of the Company’s other leases will have ended by the first quarter of 2019 and, therefore, will not require modified retrospective disclosures applied within the consolidated financial statements upon adoption of the standard.