Organization and Summary of Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2019
Organization and Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The Company’s condensed consolidated financial information as of September 30, 2019, and the three and nine months ended September 30, 2019 and 2018 is unaudited but includes all adjustments (consisting only of normal recurring adjustments), which are considered necessary for a fair presentation of the financial position at such date and of the operating results and cash flows for those periods, and have been prepared in accordance with United States generally accepted accounting principles (“GAAP”) for interim financial information. Accordingly, they do not include all of the information and notes required by GAAP for complete financial statements. The accompanying unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated December 31, 2018 financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018, filed with the Securities and Exchange Commission (“SEC”) on February 28, 2019. The results for the three and nine months ended September 30, 2019 are not necessarily indicative of the results to be expected for the year ending December 31, 2019, or for any other interim period or for any future period. These condensed consolidated financial statements include the accounts of the Company and its subsidiaries, and intercompany transactions and balances have been eliminated.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosures in the condensed consolidated financial statements and accompanying notes. Management bases its estimates on historical experience and on assumptions believed to be reasonable under the circumstances. Actual results could differ materially from those estimates.
Significant Accounting Policies	Significant Accounting Policies Other than the recently adopted accounting pronouncements below, there have been no material revisions in the Company’s significant accounting policies described in Note 1 to the consolidated financial statements included in its Annual Report on Form 10-K for the year ended December 31, 2018.
Recently Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements Effective January 1, 2019, the Company adopted Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842) (“ASU 2016-02”) under the required modified retrospective approach. ASU 2016-02 was aimed at making leasing activities more transparent and comparable, and requires leases with terms greater than one year to be recognized by lessees on their balance sheet as a right-of-use asset and corresponding lease liability. The Company elected the optional transition method to initially account for the impact of the adoption with a cumulative adjustment to accumulated deficit, if any, on the effective date of ASU 2016-02 of January 1, 2019, rather than applying the transition provisions in the earliest period presented, and the Company elected a package of practical expedients that allowed entities to not: (i) reassess whether any expired or existing contracts are considered or contain leases; (ii) reassess the lease classification for any expired or existing leases; and (iii) reassess initial direct costs for any existing leases. In addition, the Company elected other practical expedients that allowed entities to: (i) use hindsight in determining the term of a lease when the lease includes an option to extend the lease term; (ii) exclude all leases, on a go forward basis, that have a lease term of 12-months or less; and (iii) combine lease and non-lease components (e.g., office common area maintenance expenses) when recognizing a lease on an entity’s balance sheet on a go forward basis. As a result of the adoption of ASU 2016-02, on January 1, 2019, the Company recorded a right-of-use operating lease asset of $48.3 million and an operating lease liability of $56.3 million related to its office leases in South San Francisco, California and Dublin, Ireland. The lease liability included $8.0 million related to deferred rent liabilities. The adoption of ASU 2016-02 did not have an impact on the Company’s consolidated results of operations, lease expense, or cash flows. Effective January 1, 2019, the Company adopted ASU 2017-09, Compensation – Stock Compensation (Topic 718): Scope of Modification Accounting (“ASU 2017-09”). ASU 2017-09 was issued to provide clarity and reduce both (i) diversity in practice and (ii) cost and complexity when applying the guidance in Topic 718, Compensation—Stock Compensation, to a change to the terms or conditions of a share-based payment award. The amendments in ASU 2017-09 provided guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. Essentially, an entity will not have to account for the effects of a modification if: (i) the fair value of the modified award is the same immediately before and after the modification; (ii) the vesting conditions of the modified award are the same immediately before and after the modification; and (iii) the classification of the modified award as either an equity instrument or liability instrument is the same immediately before and after the modification. The adoption of ASU 2017-09 did not have a material impact on the Company’s consolidated financial statements and related disclosures as of January 1, 2019. Effective January 1, 2019, the Company adopted the new final rule under SEC Release No. 33-10532, Disclosure Update and Simplification, amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders’ equity for interim financial statements. Under the amendments, an analysis of changes in each caption of stockholders’ equity presented in the balance sheet must be provided in a note or separate statement. The analysis should present a reconciliation of the beginning balance to the ending balance of each period for which a statement of comprehensive income is required to be filed. The Company has included condensed consolidated statements of shareholders’ equity (deficit) in this Form 10-Q for the three and nine months ended September 30, 2019 and 2018. Recently Issued Accounting Pronouncements Not Yet Adopted In June 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13"). This guidance requires that financial assets measured at amortized cost be presented at the net amount expected to be collected. The measurement of expected credit losses is based on historical experience, current conditions, and reasonable and supportable forecasts that affect collectability. ASU 2016-13 also eliminates the concept of “other-than-temporary” impairment when evaluating available-for-sale debt securities and instead focuses on determining whether any impairment is a result of a credit loss or other factors. An entity will recognize an allowance for credit losses on available-for-sale debt securities rather than an other-than-temporary impairment that reduces the cost basis of the investment. ASU 2016-13 is effective for annual reporting periods and interim periods within those years beginning after December 15, 2019. The Company does not currently expect ASU 2016-13 to have a material impact on its consolidated financial statements and related disclosures based on the historically high credit quality of the Company’s financial instruments. In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (“ASU 2018-15”). ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. Accordingly, ASU 2018-15 requires a customer in a hosting arrangement that is a service contract to follow the guidance in Subtopic 350-40 to determine which implementation costs to capitalize as an asset related to the service contract and which costs to expense. ASU 2018-15 is effective for annual reporting periods and interim periods within those years beginning after December 15, 2019. The Company is currently evaluating the impact of adopting ASU 2018-15 on its consolidated financial statements and related disclosures. In November 2018, the FASB issued ASU 2018-18, Collaboration Arrangements: Clarifying the Interaction between Topic 808 and Topic 606 (“ASU 2018-18”). The issuance of Topic 606 raised questions about the interaction between the guidance on collaborative arrangements and revenue recognition. ASU 2018-18 addresses this uncertainty by: (i) clarifying that certain transactions between collaborative arrangement participants should be accounted for as revenue under ASC 606 when the collaboration arrangement participant is a customer; (ii) adding unit of account guidance to assess whether the collaboration arrangement or a part of the arrangement is with a customer; and (iii) precluding a company from presenting transactions with collaboration arrangement participants that are not directly related to sales to third parties together with revenue from contracts with customers. ASU 2018-18 is effective for annual reporting periods and interim periods within those years beginning after December 15, 2019. Early adoption is permitted. The Company is currently evaluating the impact of adopting ASU 2018-18 on its consolidated financial statements and related disclosures. The Company is currently evaluating other recently issued accounting pronouncements and does not currently believe that any of those pronouncements will have a material impact on its consolidated financial statements and related disclosures.

Organization and Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2019

Organization and Summary of Significant Accounting Policies

The Company’s condensed consolidated financial information as of September 30, 2019, and the three and nine months ended September 30, 2019 and 2018 is unaudited but includes all adjustments (consisting only of normal recurring adjustments), which are considered necessary for a fair presentation of the financial position at such date and of the operating results and cash flows for those periods, and have been prepared in accordance with United States generally accepted accounting principles (“GAAP”) for interim financial information. Accordingly, they do not include all of the information and notes required by GAAP for complete financial statements. The accompanying unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated December 31, 2018 financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018, filed with the Securities and Exchange Commission (“SEC”) on February 28, 2019.

The results for the three and nine months ended September 30, 2019 are not necessarily indicative of the results to be expected for the year ending December 31, 2019, or for any other interim period or for any future period. These condensed consolidated financial statements include the accounts of the Company and its subsidiaries, and intercompany transactions and balances have been eliminated.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and related disclosures in the condensed consolidated financial statements and accompanying notes. Management bases its estimates on historical experience and on assumptions believed to be reasonable under the circumstances. Actual results could differ materially from those estimates.

Significant Accounting Policies

Other than the recently adopted accounting pronouncements below, there have been no material revisions in the Company’s significant accounting policies described in Note 1 to the consolidated financial statements included in its Annual Report on Form 10-K for the year ended December 31, 2018.

Recently Issued Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Effective January 1, 2019, the Company adopted Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842) (“ASU 2016-02”) under the required modified retrospective approach. ASU 2016-02 was aimed at making leasing activities more transparent and comparable, and requires leases with terms greater than one year to be recognized by lessees on their balance sheet as a right-of-use asset and corresponding lease liability.

The Company elected the optional transition method to initially account for the impact of the adoption with a cumulative adjustment to accumulated deficit, if any, on the effective date of ASU 2016-02 of January 1, 2019, rather than applying the transition provisions in the earliest period presented, and the Company elected a package of practical expedients that allowed entities to not: (i) reassess whether any expired or existing contracts are considered or contain leases; (ii) reassess the lease classification for any expired or existing leases; and (iii) reassess initial direct costs for any existing leases. In addition, the Company elected other practical expedients that allowed entities to: (i) use hindsight in determining the term

of a lease when the lease includes an option to extend the lease term; (ii) exclude all leases, on a go forward basis, that have a lease term of 12-months or less; and (iii) combine lease and non-lease components (e.g., office common area maintenance expenses) when recognizing a lease on an entity’s balance sheet on a go forward basis.

As a result of the adoption of ASU 2016-02, on January 1, 2019, the Company recorded a right-of-use operating lease asset of $48.3 million and an operating lease liability of $56.3 million related to its office leases in South San Francisco, California and Dublin, Ireland. The lease liability included $8.0 million related to deferred rent liabilities. The adoption of ASU 2016-02 did not have an impact on the Company’s consolidated results of operations, lease expense, or cash flows.

Effective January 1, 2019, the Company adopted ASU 2017-09, Compensation – Stock Compensation (Topic 718): Scope of Modification Accounting (“ASU 2017-09”). ASU 2017-09 was issued to provide clarity and reduce both (i) diversity in practice and (ii) cost and complexity when applying the guidance in Topic 718, Compensation—Stock Compensation, to a change to the terms or conditions of a share-based payment award. The amendments in ASU 2017-09 provided guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. Essentially, an entity will not have to account for the effects of a modification if: (i) the fair value of the modified award is the same immediately before and after the modification; (ii) the vesting conditions of the modified award are the same immediately before and after the modification; and (iii) the classification of the modified award as either an equity instrument or liability instrument is the same immediately before and after the modification. The adoption of ASU 2017-09 did not have a material impact on the Company’s consolidated financial statements and related disclosures as of January 1, 2019.

Effective January 1, 2019, the Company adopted the new final rule under SEC Release No. 33-10532, Disclosure Update and Simplification, amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders’ equity for interim financial statements. Under the amendments, an analysis of changes in each caption of stockholders’ equity presented in the balance sheet must be provided in a note or separate statement. The analysis should present a reconciliation of the beginning balance to the ending balance of each period for which a statement of comprehensive income is required to be filed. The Company has included condensed consolidated statements of shareholders’ equity (deficit) in this Form 10-Q for the three and nine months ended September 30, 2019 and 2018.

Recently Issued Accounting Pronouncements Not Yet Adopted

In June 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (“ASU 2016-13"). This guidance requires that financial assets measured at amortized cost be presented at the net amount expected to be collected. The measurement of expected credit losses is based on historical experience, current conditions, and reasonable and supportable forecasts that affect collectability. ASU 2016-13 also eliminates the concept of “other-than-temporary” impairment when evaluating available-for-sale debt securities and instead focuses on determining whether any impairment is a result of a credit loss or other factors. An entity will recognize an allowance for credit losses on available-for-sale debt securities rather than an other-than-temporary impairment that reduces the cost basis of the investment. ASU 2016-13 is effective for annual reporting periods and interim periods within those years beginning after December 15, 2019. The Company does not currently expect ASU 2016-13 to have a material impact on its consolidated financial statements and related disclosures based on the historically high credit quality of the Company’s financial instruments.

In August 2018, the FASB issued ASU 2018-15, Intangibles-Goodwill and Other-Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (“ASU 2018-15”). ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. Accordingly, ASU 2018-15 requires a customer in a hosting arrangement that is a service contract to follow the guidance in Subtopic 350-40 to determine which implementation costs to capitalize as an asset related to the service contract and which costs to expense. ASU 2018-15 is effective for annual reporting periods and interim periods within those years beginning after December 15, 2019. The Company is currently evaluating the impact of adopting ASU 2018-15 on its consolidated financial statements and related disclosures.

In November 2018, the FASB issued ASU 2018-18, Collaboration Arrangements: Clarifying the Interaction between Topic 808 and Topic 606 (“ASU 2018-18”). The issuance of Topic 606 raised questions about the interaction between the guidance on collaborative arrangements and revenue recognition. ASU 2018-18 addresses this uncertainty by: (i) clarifying that certain transactions between collaborative arrangement participants should be accounted for as revenue under ASC 606 when the collaboration arrangement participant is a customer; (ii) adding unit of account guidance to assess whether the collaboration arrangement or a part of the arrangement is with a customer; and (iii) precluding a company from presenting transactions with collaboration arrangement participants that are not directly related to sales to third parties together with revenue from contracts with customers. ASU 2018-18 is effective for annual reporting periods and interim periods within those years beginning after December 15, 2019. Early adoption is permitted. The Company is currently evaluating the impact of adopting ASU 2018-18 on its consolidated financial statements and related disclosures.

The Company is currently evaluating other recently issued accounting pronouncements and does not currently believe that any of those pronouncements will have a material impact on its consolidated financial statements and related disclosures.