Basis of Presentation and Summary of Significant Accounting Policies	3 Months Ended
Mar. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation and Consolidation The accompanying condensed consolidated financial statements as of March 31, 2020 and December 31, 2019, and for the three months ended March 31, 2020 and 2019, have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the “SEC”) and generally accepted accounting principles in the United States of America (“GAAP”) as found in the Accounting Standards Codification (“ASC”) of the Financial Accounting Standards Board (“FASB”) for condensed consolidated financial information. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, these condensed consolidated financial statements reflect all normal recurring adjustments which are necessary for a fair presentation of the Company’s financial position and results of its operations, as of and for the periods presented. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 filed with the SEC on February 27, 2020 (the “Annual Report on Form 10-K”). The information presented in the condensed consolidated financial statements and related notes as of March 31, 2020, and for the three months ended March 31, 2020 and 2019, is unaudited. The December 31, 2019 condensed consolidated balance sheet included herein was derived from the audited financial statements as of that date, but does not include all disclosures, including notes, required by GAAP for complete financial statements. Interim results for the three months ended March 31, 2020 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2020, or any future period. The accompanying condensed consolidated financial statements include the accounts of Jounce Therapeutics, Inc. and its wholly-owned subsidiary, Jounce Mass Securities, Inc. All intercompany transactions and balances have been eliminated in consolidation. Summary of Significant Accounting Policies The significant accounting policies and estimates used in the preparation of the condensed consolidated financial statements are described in the Company’s audited financial statements as of and for the year ended December 31, 2019, and the notes thereto, which are included in the Annual Report on Form 10-K. There have been no material changes in the Company’s significant accounting policies during the three months ended March 31, 2020. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company’s management evaluates its estimates which include, but are not limited to, accrued expenses, stock-based compensation expense and income taxes. The Company bases its estimates on historical experience and other market specific or other relevant assumptions it believes to be reasonable under the circumstances. Actual results could differ from those estimates. Recent Accounting Pronouncements In June 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. This standard requires that credit losses be reported using an expected losses model rather than the incurred losses model that is currently used, and it establishes additional disclosure requirements related to credit risks. For available-for-sale debt securities with expected credit losses, this standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. This guidance was originally effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and early adoption was permitted. In November 2019, the FASB subsequently issued ASU 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates, whereby the effective date of this standard for smaller reporting companies was deferred to fiscal years beginning after December 15, 2022, including interim periods within those fiscal years, and early adoption is still permitted. Accordingly, the Company will now adopt this standard effective January 1, 2023, and it is currently evaluating the potential impact that ASU 2016-13 may have on the consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, which eliminates, adds and modifies certain disclosure requirements for fair value measurements. This guidance became effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Accordingly, the Company adopted ASU 2018-13 effective January 1, 2020, and there was no impact to the condensed consolidated financial statements due to the adoption of this guidance. 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. This guidance 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 (and hosting arrangements that include an internal-use software license). The accounting for the service element of a hosting arrangement that is a service contract is not affected. This guidance became effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The amendments in this update are able to be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. Accordingly, the Company adopted ASU 2018-15 effective January 1, 2020, and it elected to apply this guidance on a prospective basis. There was no impact to the condensed consolidated financial statements due to the adoption of this guidance. In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606, which clarifies that certain transactions between participants in a collaborative arrangement should be accounted for under ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”) when the counterparty is a customer. In addition, ASU 2018-18 adds unit-of-account guidance to ASC Topic 808, Collaborative Arrangements, in order to align this guidance with ASC 606 and also precludes an entity from presenting consideration from a transaction in a collaborative arrangement as revenue from contracts with customers if the counterparty is not a customer for that transaction. This guidance became effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Accordingly, the Company adopted ASU 2018-18 effective January 1, 2020, and there was no impact to the condensed consolidated financial statements due to the adoption of this guidance. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which eliminates certain exceptions to the guidance in ASC 740 related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities when investment ownership changes. In addition, ASU 2019-12 simplifies the accounting for the interim period effects of changes in tax laws or rates and transactions that result in a step-up in the tax basis of goodwill. While this guidance is effective for fiscal years beginning after December 15, 2020, including interim periods within those fiscal years, early adoption is permitted. Consequently, the Company elected to early adopt ASU 2019-12 effective January 1, 2020. Due to the adoption of this guidance, the Company did not record an intraperiod tax allocation to other comprehensive income for the three months ended March 31, 2020. In accordance with ASU 2019-12, the Company has applied the new provisions related to the intraperiod tax allocation on a prospective basis.

Basis of Presentation and Summary of Significant Accounting Policies

Basis of Presentation and Consolidation

The accompanying condensed consolidated financial statements as of March 31, 2020 and December 31, 2019, and for the three months ended March 31, 2020 and 2019, have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the “SEC”) and generally accepted accounting principles in the United States of America (“GAAP”) as found in the Accounting Standards Codification (“ASC”) of the Financial Accounting Standards Board (“FASB”) for condensed consolidated financial information. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, these condensed consolidated financial statements reflect all normal recurring adjustments which are necessary for a fair presentation of the Company’s financial position and results of its operations, as of and for the periods presented. These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 filed with the SEC on February 27, 2020 (the “Annual Report on Form 10-K”).

The information presented in the condensed consolidated financial statements and related notes as of March 31, 2020, and for the three months ended March 31, 2020 and 2019, is unaudited. The December 31, 2019 condensed consolidated balance sheet included herein was derived from the audited financial statements as of that date, but does not include all disclosures, including notes, required by GAAP for complete financial statements.

Interim results for the three months ended March 31, 2020 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2020, or any future period.

The accompanying condensed consolidated financial statements include the accounts of Jounce Therapeutics, Inc. and its wholly-owned subsidiary, Jounce Mass Securities, Inc. All intercompany transactions and balances have been eliminated in consolidation.

Summary of Significant Accounting Policies

The significant accounting policies and estimates used in the preparation of the condensed consolidated financial statements are described in the Company’s audited financial statements as of and for the year ended December 31, 2019, and the notes thereto, which are included in the Annual Report on Form 10-K. There have been no material changes in the Company’s significant accounting policies during the three months ended March 31, 2020.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company’s management evaluates its estimates which include, but are not limited to, accrued expenses, stock-based compensation expense and income taxes. The Company bases its estimates on historical experience and other market specific or other relevant assumptions it believes to be reasonable under the circumstances. Actual results could differ from those estimates.

Recent Accounting Pronouncements

In June 2016, the FASB issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. This standard requires that credit losses be reported using an expected losses model rather than the incurred losses model that is currently used, and it establishes additional disclosure requirements related to credit risks. For available-for-sale debt securities with expected credit losses, this standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. This guidance was originally effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and early adoption was permitted. In November 2019, the FASB subsequently issued ASU 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842): Effective Dates, whereby the effective date of this standard for smaller reporting companies was deferred to fiscal years beginning after December 15, 2022, including interim periods within those fiscal years, and early adoption is still permitted. Accordingly, the Company will now adopt this standard effective January 1, 2023, and it is currently evaluating the potential impact that ASU 2016-13 may have on the consolidated financial statements.

In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, which eliminates, adds and modifies certain disclosure requirements for fair value measurements. This guidance became effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Accordingly, the Company adopted ASU 2018-13 effective January 1, 2020, and there was no impact to the condensed consolidated financial statements due to the adoption of this guidance.

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. This guidance 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 (and hosting arrangements that include an internal-use software license). The accounting for the service element of a hosting arrangement that is a service contract is not affected. This guidance became effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The amendments in this update are able to be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. Accordingly, the Company adopted ASU 2018-15 effective January 1, 2020, and it elected to apply this guidance on a prospective basis. There was no impact to the condensed consolidated financial statements due to the adoption of this guidance.

In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606, which clarifies that certain transactions between participants in a collaborative arrangement should be accounted for under ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”) when the counterparty is a customer. In addition, ASU 2018-18 adds unit-of-account guidance to ASC Topic 808, Collaborative Arrangements, in order to align this guidance with ASC 606 and also precludes an entity from presenting consideration from a transaction in a collaborative arrangement as revenue from contracts with customers if the counterparty is not a customer for that transaction. This guidance became effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. Accordingly, the Company adopted ASU 2018-18 effective January 1, 2020, and there was no impact to the condensed consolidated financial statements due to the adoption of this guidance.

In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which eliminates certain exceptions to the guidance in ASC 740 related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities when investment ownership changes. In addition, ASU 2019-12 simplifies the accounting for the interim period effects of changes in tax laws or rates and transactions that result in a step-up in the tax basis of goodwill. While this guidance is effective for fiscal years beginning after December 15, 2020, including interim periods within those fiscal years, early adoption is permitted. Consequently, the Company elected to early adopt ASU 2019-12 effective January 1, 2020. Due to the adoption of this guidance, the Company did not record an intraperiod tax allocation to other comprehensive income for the three months ended March 31, 2020. In accordance with ASU 2019-12, the Company has applied the new provisions related to the intraperiod tax allocation on a prospective basis.