General (Policies)	9 Months Ended
Sep. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Risk and Uncertainties	Risks and Uncertainties Due to the global outbreak of SARS-CoV-2, a novel strain of coronavirus that causes Coronavirus disease (COVID-19), the Company experienced an impact on certain areas of its business. These effects included a slowing of patient recruitment in the FOCUS trial and a reduction in the pace at which we can monitor data at our clinical trial sites. The resulting delay in completing enrollment and additional time required to monitor data caused our announcement for the top-line data from our FOCUS Trial to shift to early 2021 and to be modified to a preliminary analysis. We now plan to submit a New Drug Application (NDA) to the FDA in the first quarter of 2022 for the treatment of mOM. The ability to achieve this goal is contingent on our ability to monitor data at our clinical sites and therefore the timeline may shift as access to the clinical sites changes in response to the rapidly evolving situation. We have also experienced an increased volatility in EU commercial product revenue and additional impacts to the business may arise that we are not aware of currently. The ultimate impact of the pandemic on the Company’s results of operations, financial position, liquidity, or capital resources cannot be reasonably estimated at this time.
Liquidity and Going Concern	Liquidity and Going Concern The accompanying interim condensed consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. The Company has incurred losses since inception and expects to continue incurring losses for the next several years. These losses, among other factors, raise substantial doubt about the Company’s ability to continue as a going concern. The Company’s existence is dependent upon management’s ability to obtain additional funding sources or to enter into strategic alliances. Adequate additional financing may not be available to the Company on acceptable terms, or at all. If the Company is unable to raise additional capital and/or enter into strategic alliances when needed or on attractive terms, it would be forced to delay, reduce, or eliminate its research and development programs or any commercialization efforts. There can be no assurance that the Company’s efforts will result in the resolution of the Company’s liquidity needs. If Delcath is not able to continue as a going concern, it is likely that holders of its common stock will lose all of their investment. The accompanying interim condensed consolidated financial statements do not include any adjustments that might result should the Company be unable to continue as a going concern. The Company anticipates incurring additional losses until such time, if ever, that it can generate significant sales. These circumstances raise substantial doubt about the Company's ability to continue as a going concern within one year after the date that the financial statements are issued. Additional working capital is required to continue operations. Operations of the Company are subject to certain risks and uncertainties, including, among others, uncertainty of product development and clinical trial results; uncertainty regarding regulatory approval; technological uncertainty; uncertainty regarding patents and proprietary rights; comprehensive government regulations; limited commercial manufacturing, marketing, or sales experience; and dependence on key personnel.
Basis of Presentation	Basis of Presentation These interim condensed consolidated financial statements are unaudited and were prepared by the Company in accordance with generally accepted accounting principles in the United States of America (GAAP) and with the SEC’s instructions to Form 10-Q and Article 10 of Regulation S-X. They include the accounts of all entities controlled by Delcath and all significant inter-company accounts and transactions have been eliminated in consolidation. The preparation of interim condensed consolidated financial statements requires management to make assumptions and estimates that impact the amounts reported. These interim condensed consolidated financial statements reflect all adjustments, consisting of normal recurring accruals, necessary for a fair presentation of the Company’s results of operations, financial position and cash flows for the interim periods ended September 30, 2021 and 2020; however, certain information and footnote disclosures normally included in our audited consolidated financial statements included in our Annual Report on Form 10-K have been condensed or omitted as permitted by GAAP. It is important to note that the Company’s results of operations and cash flows for interim periods are not necessarily indicative of the results of operations and cash flows to be expected for a full fiscal year or any interim period.
Reclassifications	Reclassifications Certain prior period balances have been reclassified in order to conform to current period presentation. These reclassifications have no effect on previously reported results of operations or loss per share.
Recently Adopted and Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements In December 2019, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2019-12, Simplifying the Accounting for Income Taxes. The list of changes is comprehensive; however, the changes will not significantly impact the Company due to the full valuation allowance that is recorded against the Company’s deferred tax assets. Early adoption of ASU 2019-12 is permitted, including adoption in any interim period for public business entities for periods for which financial statements have not yet been issued. An entity that elects to early adopt the amendments in an interim period should reflect any adjustments as of the beginning of the annual period that includes that interim period. Additionally, an entity that elects early adoption must adopt all the amendments in the same period. The Company adopted ASU 2019-12 on January 1, 2021, and there was no material impact on the Company’s financial statements or disclosures. Recently Issued Accounting Pronouncements On May 3, 2021, the FASB issued ASU 2021-04, Earnings Per Share (Topic 260), Debt—Modifications and Extinguishments (Subtopic 470-50), Compensation—Stock Compensation (Topic 718), and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Issuer’s Accounting for Certain Modifications or Exchanges of Freestanding Equity-Classified Written Call Options. This new standard provides clarification and reduces diversity in an issuer’s accounting for modifications or exchanges of freestanding equity-classified written call options (such as warrants) that remain equity classified after modification or exchange. This standard is effective for fiscal years beginning after December 15, 2021, including interim periods within those fiscal years. Issuers should apply the new standard prospectively to modifications or exchanges occurring after the effective date of the new standard. Early adoption is permitted, including adoption in an interim period. If an issuer elects to early adopt the new standard in an interim period, the guidance should be applied as of the beginning of the fiscal year that includes that interim period. The Company is evaluating this new standard.

General (Policies)

9 Months Ended

Sep. 30, 2021

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Risks and Uncertainties

Due to the global outbreak of SARS-CoV-2, a novel strain of coronavirus that causes Coronavirus disease (COVID-19), the Company experienced an impact on certain areas of its business. These effects included a slowing of patient recruitment in the FOCUS trial and a reduction in the pace at which we can monitor data at our clinical trial sites. The resulting delay in completing enrollment and additional time required to monitor data caused our announcement for the top-line data from our FOCUS Trial to shift to early 2021 and to be modified to a preliminary analysis. We now plan to submit a New Drug Application (NDA) to the FDA in the first quarter of 2022 for the treatment of mOM. The ability to achieve this goal is contingent on our ability to monitor data at our clinical sites and therefore the timeline may shift as access to the clinical sites changes in response to the rapidly evolving situation. We have also experienced an increased volatility in EU commercial product revenue and additional impacts to the business may arise that we are not aware of currently. The ultimate impact of the pandemic on the Company’s results of operations, financial position, liquidity, or capital resources cannot be reasonably estimated at this time.

Liquidity and Going Concern

The accompanying interim condensed consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. The Company has incurred losses since inception and expects to continue incurring losses for the next several years. These losses, among other factors, raise substantial doubt about the Company’s ability to continue as a going concern. The Company’s existence is dependent upon management’s ability to obtain additional funding sources or to enter into strategic alliances. Adequate additional financing may not be available to the Company on acceptable terms, or at all. If the Company is unable to raise additional capital and/or enter into strategic alliances when needed or on attractive terms, it would be forced to delay, reduce, or eliminate its research and development programs or any commercialization efforts. There can be no assurance that the Company’s efforts will result in the resolution of the Company’s liquidity needs. If Delcath is not able to continue as a going concern, it is likely that holders of its common stock will lose all of their investment. The accompanying interim condensed consolidated financial statements do not include any adjustments that might result should the Company be unable to continue as a going concern.

The Company anticipates incurring additional losses until such time, if ever, that it can generate significant sales. These circumstances raise substantial doubt about the Company's ability to continue as a going concern within one year after the date that the financial statements are issued. Additional working capital is required to continue operations. Operations of the Company are subject to certain risks and uncertainties, including, among others, uncertainty of product development and clinical trial results; uncertainty regarding regulatory approval; technological uncertainty; uncertainty regarding patents and proprietary rights; comprehensive government regulations; limited commercial manufacturing, marketing, or sales experience; and dependence on key personnel.

Basis of Presentation

These interim condensed consolidated financial statements are unaudited and were prepared by the Company in accordance with generally accepted accounting principles in the United States of America (GAAP) and with the SEC’s instructions to Form 10-Q and Article 10 of Regulation S-X. They include the accounts of all entities controlled by Delcath and all significant inter-company accounts and transactions have been eliminated in consolidation.

The preparation of interim condensed consolidated financial statements requires management to make assumptions and estimates that impact the amounts reported. These interim condensed consolidated financial statements reflect all adjustments, consisting of normal recurring accruals, necessary for a fair presentation of the Company’s results of operations, financial position and cash flows for the interim periods ended September 30, 2021 and 2020; however, certain information and footnote disclosures normally included in our audited consolidated financial statements included in our Annual Report on Form 10-K have been condensed or omitted as permitted by GAAP. It is important to note that the Company’s results of operations and cash flows for interim periods are not necessarily indicative of the results of operations and cash flows to be expected for a full fiscal year or any interim period.

Reclassifications

Certain prior period balances have been reclassified in order to conform to current period presentation. These reclassifications have no effect on previously reported results of operations or loss per share.

Recently Adopted and Issued Accounting Pronouncements

Recently Adopted Accounting Pronouncements

In December 2019, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2019-12, Simplifying the Accounting for Income Taxes. The list of changes is comprehensive; however, the changes will not significantly impact the Company due to the full valuation allowance that is recorded against the Company’s deferred tax assets. Early adoption of ASU 2019-12 is permitted, including adoption in any interim period for public business entities for periods for which financial statements have not yet been issued. An entity that elects to early adopt the amendments in an interim period should reflect any adjustments as of the beginning of the annual period that includes that interim period. Additionally, an entity that elects early adoption must adopt all the amendments in the same period. The Company adopted ASU 2019-12 on January 1, 2021, and there was no material impact on the Company’s financial statements or disclosures.

Recently Issued Accounting Pronouncements

On May 3, 2021, the FASB issued ASU 2021-04, Earnings Per Share (Topic 260), Debt—Modifications and Extinguishments (Subtopic 470-50), Compensation—Stock Compensation (Topic 718), and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Issuer’s Accounting for Certain Modifications or Exchanges of Freestanding Equity-Classified Written Call Options. This new standard provides clarification and reduces diversity in an issuer’s accounting for modifications or exchanges of freestanding equity-classified written call options (such as warrants) that remain equity classified after modification or exchange. This standard is effective for fiscal years beginning after December 15, 2021, including interim periods within those fiscal years. Issuers should apply the new standard prospectively to modifications or exchanges occurring after the effective date of the new standard. Early adoption is permitted, including adoption in an interim period. If an issuer elects to early adopt the new standard in an interim period, the guidance should be applied as of the beginning of the fiscal year that includes that interim period. The Company is evaluating this new standard.