General (Policies)	9 Months Ended
Sep. 30, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Liquidity and Operating Matters	Liquidity and Operating Matters 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. There can be no assurance that the Company’s efforts will result in the resolution of the Company’s liquidity needs. The accompanying statements do not include any adjustments that might result should the Company be unable to continue as a going concern.
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, in the opinion of management, 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, 2019 and 2018; however, certain information and footnote disclosures normally included in our Annual Report 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.
Derivative Financial Instruments	Derivative Financial Instruments The accounting treatment of derivative financial instruments requires that the Company record financial instruments at their fair value as of the inception date of the agreement and at fair value as of each subsequent balance sheet date. Any change in fair value is recorded as non-operating, non-cash income or expense for each reporting period at each balance sheet date. The Company reassesses the classification of its derivative instruments at each balance sheet date. If the classification changes as a result of events during the period, the contract is reclassified as of the date of the event that caused the reclassification. As a result of issuing such instruments the Company has adopted a sequencing policy in accordance with ASC 815-40-35-12 whereby all future instruments may be classified as a derivative liability with the exception of instruments related to share-based compensation issued to employees. However, the Company has recognized the Series E Preferred Stock and Series E-1 Preferred Stock issued in July 2019 and August 2019 as equity because the agreements related to the issuance of those instruments specifically state that the common shares underlying the Preferred Stock take priority in registration. Additionally, the Company has a sufficient number of authorized shares for the issuance of common shares upon the conversion of the Preferred Stock. The Company did not have sufficient authorized shares to settle the associated warrants and accordingly has classified such warrants as a liability in the accompanying financial statements.
Recently Adopted and Issued Accounting Pronouncements	Recently Adopted Accounting Pronouncements In February 2018, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220). ASU 2018-02 allows a company to elect a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. ASU 2018-02 is effective for periods beginning after December 15, 2018. Upon adoption of ASU 2018-02, the Company did not elect to reclassify the tax effects of the Tax Cuts and Jobs Act from accumulated other comprehensive income to retained earnings, as the stranded tax effects were insignificant. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) effective January 1, 2019, electing the practical expedients and applying the transition provisions as of the effective date. Reporting periods beginning on or after January 1, 2019 are presented under Topic 842, while prior period amounts, as reported under previous GAAP, were not adjusted. The adoption of Topic 842 on January 1, 2019 did not have a significant impact on the Company’s consolidated results of operations or cash flows.

General (Policies)

9 Months Ended

Sep. 30, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

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. There can be no assurance that the Company’s efforts will result in the resolution of the Company’s liquidity needs. The accompanying statements do not include any adjustments that might result should the Company be unable to continue as a going concern.

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, in the opinion of management, 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, 2019 and 2018; however, certain information and footnote disclosures normally included in our Annual Report 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.

Derivative Financial Instruments

The accounting treatment of derivative financial instruments requires that the Company record financial instruments at their fair value as of the inception date of the agreement and at fair value as of each subsequent balance sheet date. Any change in fair value is recorded as non-operating, non-cash income or expense for each reporting period at each balance sheet date. The Company reassesses the classification of its derivative instruments at each balance sheet date. If the classification changes as a result of events during the period, the contract is reclassified as of the date of the event that caused the reclassification. As a result of issuing such instruments the Company has adopted a sequencing policy in accordance with ASC 815-40-35-12 whereby all future instruments may be classified as a derivative liability with the exception of instruments related to share-based compensation issued to employees. However, the Company has recognized the Series E Preferred Stock and Series E-1 Preferred Stock issued in July 2019 and August 2019 as equity because the agreements related to the issuance of those instruments specifically state that the common shares underlying the Preferred Stock take priority in registration. Additionally, the Company has a sufficient number of authorized shares for the issuance of common shares upon the conversion of the Preferred Stock. The Company did not have sufficient authorized shares to settle the associated warrants and accordingly has classified such warrants as a liability in the accompanying financial statements.

Recently Adopted and Issued Accounting Pronouncements

Recently Adopted Accounting Pronouncements

In February 2018, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220). ASU 2018-02 allows a company to elect a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. ASU 2018-02 is effective for periods beginning after December 15, 2018. Upon adoption of ASU 2018-02, the Company did not elect to reclassify the tax effects of the Tax Cuts and Jobs Act from accumulated other comprehensive income to retained earnings, as the stranded tax effects were insignificant.

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) effective January 1, 2019, electing the practical expedients and applying the transition provisions as of the effective date. Reporting periods beginning on or after January 1, 2019 are presented under Topic 842, while prior period amounts, as reported under previous GAAP, were not adjusted. The adoption of Topic 842 on January 1, 2019 did not have a significant impact on the Company’s consolidated results of operations or cash flows.