Significant Accounting Policies (Policies)	9 Months Ended
Significant Accounting Policies (Policies)	Sep. 30, 2020
Accounting Policies [Abstract]
Basis of presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements as of September 30, 2020 and December 31, 2019, and for the three and nine months ended September 30, 2020 and 2019, have been presented in conformity with generally accepted accounting principles in the United States (“GAAP”). Certain amounts from the prior period have been reclassified to conform to the current year presentation. Specifically, in the accompanying unaudited condensed consolidated balance sheet, right-of-use assets and non-current lease liabilities are presented separately.
Principles of consolidation	Principles of Consolidation The accompanying unaudited condensed consolidated financial statements include the accounts of Exicure, Inc. and its wholly owned subsidiary, Exicure Operating Company. All intercompany transactions and accounts are eliminated in consolidation.
Use of estimates	Use of Estimates The preparation of the financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Management bases its estimates on certain assumptions which it believes are reasonable in the circumstances and while actual results could differ from those estimates, management does not believe that any change in those assumptions in the near term would have a significant effect on the Company’s financial position, results of operations or cash flows. Actual results in future periods could differ from those estimates.
Recent accounting pronouncements	The Company’s significant accounting policies are disclosed in the audited consolidated financial statements and the notes thereto, which are included in the in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 filed with the U.S. Securities and Exchange Commission (“SEC”) on March 10, 2020. Since the date of those audited consolidated financial statements, there have been no material changes to the Company’s significant accounting policies. Recently Adopted Accounting Pronouncements None. Recent Accounting Pronouncements Not Yet Adopted Financial Instruments - Credit Losses In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) ASU 2016-13, Measurement of Credit Losses on Financial Instruments (“ASU 2016-13). ASU 2016-13 is a new standard intended to improve reporting requirements specific to loans, receivables and other financial instruments. ASU 2016-13 requires that credit losses on financial assets measured at amortized cost be determined using an expected loss model, instead of the current incurred loss model, and requires that credit losses related to available-for-sale debt securities be recorded through an allowance for credit losses and limited to the amount by which carrying value exceeds fair value. ASU 2016-13 also requires enhanced disclosure of credit risk associated with financial assets. The effective date of ASU 2016-13 was deferred by ASU 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842)—Effective Dates to the annual period beginning after December 15, 2022 for companies that (i) meet the definition of an SEC filer and (ii) are eligible as “smaller reporting companies” as such term is defined by the SEC, with early adoption permitted. The Company is currently assessing the impact of adoption of ASU 2016-13 to its consolidated financial statements.
Loss per common share	Basic loss per common share is calculated by dividing net loss by the weighted-average number of shares of common stock outstanding during the period. Diluted loss per common share is calculated using the treasury share method by giving effect to all potentially dilutive securities that were outstanding. Potentially dilutive options and warrants to purchase common stock that were outstanding during the periods presented were excluded from the diluted loss per share calculation for the periods presented because such shares had an anti-dilutive effect due to the net loss reported in those periods.