Summary of Significant Accounting Policies	6 Months Ended
Jun. 30, 2015
Summary of Significant Accounting Policies [Abstract]
Summary of Significant Accounting Policies	1. Basis of Presentation and Recently Issued Accounting Standards Basis of Presentation The accompanying unaudited interim consolidated financial statements of MacroGenics, Inc. (the Company) have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information. The financial statements include all adjustments (consisting only of normal recurring adjustments) that the management of the Company believes are necessary for a fair presentation of the periods presented. These interim financial results are not necessarily indicative of results expected for the full fiscal year or for any subsequent interim period. The accompanying unaudited interim consolidated financial statements include the accounts of MacroGenics, Inc. and its wholly owned subsidiary, MacroGenics UK Limited. All intercompany accounts and transactions have been eliminated in consolidation. These consolidated financial statements and related notes should be read in conjunction with the financial statements and notes thereto included in the Company's 2014 Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on March 3, 2015. There have been no material changes to the significant accounting policies previously disclosed in the Company's 2014 Annual Report on Form 10-K. Recently Issued Accounting Standards In May 2014, the Financial Accounting Standards Board (FASB) issued ASU No. 2014-09, Revenue from Contracts with Customers (ASU 2014-09). ASU 2014-09 will eliminate transaction- and industry-specific revenue recognition guidance under current GAAP and replace it with a principle-based approach for determining revenue recognition. ASU 2014-09 will require that companies recognize revenue based on the value of transferred goods or services as they occur in the contract. The ASU also will require additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. ASU 2014-09 was originally effective for annual reporting periods beginning after December 15, 2016. On July 9, 2015, the FASB voted for a one-year deferral of the effective date of the standard to annual reporting periods beginning after December 15, 2017, with an option that would permit companies to adopt the standard as early as the original effective date for annual reporting periods after December 15, 2016. Early adoption prior to the original effective date is not permitted. The new standard may be adopted either retrospectively or on a modified retrospective basis whereby the new standard would be applied to new contracts and existing contracts with remaining performance obligations as of the effective date, with a cumulative catch-up adjustment recorded to beginning retained earnings at the effective date for existing contracts with remaining performance obligations. In addition, the FASB is contemplating making additional changes to certain elements of the new standard. Management is currently assessing the impact the adoption of ASU 2014-09, as amended, will have on the Company's consolidated financial statements. In April 2015, the FASB issued ASU 2015-05, Intangibles - Goodwill and Other - Internal-Use Software: Customer's Accounting for Fees Paid in a Cloud Computing Arrangement (ASU 2015-05). ASU 2015-05 clarifies the circumstances under which a cloud computing customer would account for the arrangement as a license of internal-use software under ASC 350-40. The new accounting guidance is effective for interim and annual periods beginning after December 15, 2015 with early adoption permitted. The Company has not elected early adoption and management is evaluating the impact of the provisions of ASU 2015-05 on its consolidated financial statements.

1. Basis of Presentation and Recently Issued Accounting Standards

Basis of Presentation

The accompanying unaudited interim consolidated financial statements of MacroGenics, Inc. (the Company) have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information. The financial statements include all adjustments (consisting only of normal recurring adjustments) that the management of the Company believes are necessary for a fair presentation of the periods presented. These interim financial results are not necessarily indicative of results expected for the full fiscal year or for any subsequent interim period.

The accompanying unaudited interim consolidated financial statements include the accounts of MacroGenics, Inc. and its wholly owned subsidiary, MacroGenics UK Limited. All intercompany accounts and transactions have been eliminated in consolidation. These consolidated financial statements and related notes should be read in conjunction with the financial statements and notes thereto included in the Company's 2014 Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on March 3, 2015.

There have been no material changes to the significant accounting policies previously disclosed in the Company's 2014 Annual Report on Form 10-K.

Recently Issued Accounting Standards

In May 2014, the Financial Accounting Standards Board (FASB) issued ASU No. 2014-09, Revenue from Contracts with Customers (ASU 2014-09). ASU 2014-09 will eliminate transaction- and industry-specific revenue recognition guidance under current GAAP and replace it with a principle-based approach for determining revenue recognition. ASU 2014-09 will require that companies recognize revenue based on the value of transferred goods or services as they occur in the contract. The ASU also will require additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. ASU 2014-09 was originally effective for annual reporting periods beginning after December 15, 2016. On July 9, 2015, the FASB voted for a one-year deferral of the effective date of the standard to annual reporting periods beginning after December 15, 2017, with an option that would permit companies to adopt the standard as early as the original effective date for annual reporting periods after December 15, 2016. Early adoption prior to the original effective date is not permitted. The new standard may be adopted either retrospectively or on a modified retrospective basis whereby the new standard would be applied to new contracts and existing contracts with remaining performance obligations as of the effective date, with a cumulative catch-up adjustment recorded to beginning retained earnings at the effective date for existing contracts with remaining performance obligations. In addition, the FASB is contemplating making additional changes to certain elements of the new standard. Management is currently assessing the impact the adoption of ASU 2014-09, as amended, will have on the Company's consolidated financial statements.

In April 2015, the FASB issued ASU 2015-05, Intangibles - Goodwill and Other - Internal-Use Software: Customer's Accounting for Fees Paid in a Cloud Computing Arrangement (ASU 2015-05). ASU 2015-05 clarifies the circumstances under which a cloud computing customer would account for the arrangement as a license of internal-use software under ASC 350-40. The new accounting guidance is effective for interim and annual periods beginning after December 15, 2015 with early adoption permitted. The Company has not elected early adoption and management is evaluating the impact of the provisions of ASU 2015-05 on its consolidated financial statements.