Delcath Systems (DCTH) 10-K 25 Mar 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Mar. 23, 2020	Jun. 30, 2019
Cover [Abstract]
Entity Registrant Name	DELCATH SYSTEMS, INC.
Entity Central Index Key	0000872912
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Document Annual Report	true
Document Transition Report	false
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Incorporation, State or Country Code	DE
Entity Interactive Data Current	Yes
Entity File Number	001-16133
Entity Tax Identification Number	06-1245881
Entity Address, Address Line One	1633 Broadway
Entity Address Address Line2	Suite 22C
Entity Address City Or Town	New York
Entity Address State Or Province	NY
Entity Address Postal Zip Code	10019
City Area Code	212
Local Phone Number	489-2100
Entity Shell Company	false
Entity Public Float			$ 2,189,040
Entity Common Stock, Shares Outstanding		72,773
Document Fiscal Year Focus	2019
Trading Symbol	DCTH
Title of 12(b) Security	Common stock
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2019
Documents Incorporated by Reference	None.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands		Dec. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents		$ 10,002	$ 2,516
Restricted cash		181	1,062
Accounts receivables, net		21	585
Inventories		654	858
Prepaid expenses and other current assets		1,759	898
Total current assets		12,617	5,919
Property, plant and equipment, net		735	925
Right-of-use assets		860	0
Total assets		14,212	6,844
Current liabilities
Accounts payable		4,533	7,715
Accrued expenses		6,947	7,964
Convertible notes payable, net of debt discount		0	2,038
Lease liabilities, current portion		664	0
Warrant liability		3,368	33
Total current liabilities		15,512	17,750
Deferred revenue		2,860	3,405
Lease liabilities, long-term portion		197	0
Convertible notes payable, net of debt discount		2,000	0
Other non-current liabilities		0	628
Total liabilities		20,569	21,783
Commitments and contingencies
Stockholders' Deficit
Preferred stock, $.01 par value; 10,000,000 shares authorized; 41,517 and 101 shares issued and outstanding at December 31, 2019 and December 31, 2018, respectively		0	0
Common stock, $.01 par value; 1,000,000,000 shares authorized; 67,091 and 14,715 shares issued and outstanding at December 31, 2019 and December 31, 2018, respectively*	[1]	1	0
Additional paid-in capital		364,785	329,065
Accumulated deficit		(371,171)	(344,054)
Accumulated other comprehensive loss		28	50
Total stockholders' deficit		(6,357)	(14,939)
Total liabilities and stockholders' deficit		$ 14,212	$ 6,844
[1]	reflects, a one-for-five hundred (1:500) reverse stock split effected on May 2, 2018, and a one-for-seven hundred (1:700) reverse stock split effected on December 24, 2019.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	41,517	101
Preferred stock, shares outstanding (in shares)	41,517	101
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	67,091	14,715
Common stock, shares outstanding (in shares)	67,091	14,715

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018
Cost of goods sold		$ (719)	$ (1,009)
Gross profit		861	2,398
Operating expenses:
Research and development expenses		9,490	19,650
Selling, general and administrative expenses		11,279	9,819
Total operating expenses		20,769	29,469
Operating loss		(19,908)	(27,071)
Change in fair value of the warrant liability, net		17,493	19,706
Loss on debt extinguishment			(1,123)
Loss on issuance of financial instrument		(1,720)	(2,826)
Interest expense		(4,746)	(7,959)
Other income		2	51
Net loss		(8,879)	(19,222)
Other comprehensive loss:
Foreign currency translation adjustments		(22)	8
Comprehensive loss		$ (8,901)	$ (19,214)
Common share data:
Basic and diluted loss per share	[1]	$ (1,047)	$ (504)
Weighted average number of basic and diluted shares outstanding	[1]	25,900	38,151
Product Revenue [Member]
Revenue		$ 1,101	$ 3,378
Other Revenue [Member]
Revenue		$ 479	$ 29
[1]	reflects, a one-for-five hundred (1:500) reverse stock split effected on May 2, 2018, and a one-for-seven hundred (1:700) reverse stock split effected on December 24, 2019.

Consolidated Statements of Op_2

Consolidated Statements of Operations and Comprehensive Loss (Parenthetical)	Dec. 24, 2019	May 02, 2018
Income Statement [Abstract]
Reverse stock split	1:700	1:500
Reverse stock split ratio	0.00142	0.002

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Deficit - USD ($) $ in Thousands	Total	Series D Preferred Stock [Member]	Series E Preferred Stock [Member]	Series E-1 Preferred Stock [Member]	Common Stock [Member]	Common Stock [Member]Series D Warrants [Member]	Preferred Stock [Member]	Preferred Stock [Member]Series D Preferred Stock [Member]	Preferred Stock [Member]Series E Preferred Stock [Member]	Preferred Stock [Member]Series E-1 Preferred Stock [Member]	Treasury Stock [Member]	Additional Paid in Capital [Member]	Additional Paid in Capital [Member]Series D Preferred Stock [Member]	Additional Paid in Capital [Member]Series E Preferred Stock [Member]	Additional Paid in Capital [Member]Series E-1 Preferred Stock [Member]	Accumulated Deficit [Member]	Accumulated Deficit [Member]Series E Preferred Stock [Member]	Accumulated Deficit [Member]Series E-1 Preferred Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2017	$ 678										$ (51)	$ 325,519				$ (324,832)			$ 42
Balance (in shares) at Dec. 31, 2017					377						(1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation expense for issuance of restricted stock	98											98
Compensation expense for issuance of restricted stock (in shares)					236
Compensation income related to cancellation of stock options	(40)											(40)
Sale of common stock, net of expenses	10,916											10,916
Sale of common stock, net of expenses (in shares)					7,624
Issuance of pre-funded warrants	520											520
Cashless exercise of warrants (in shares)					49
Fair value of warrants issued with Convertible Notes	5,007											5,007
Fair value of warrants reclassified from liability to equity	4,210											4,210
Beneficial conversion feature of convertible note	44											44
Issuance of Preferred Stock		$ 1,004											$ 1,004
Issuance of Preferred Stock (in shares)								101
Fair value of warrants exchanged for Common Stock	144											144
Retirement of Treasury Stock											$ 51	(51)
Retirement of Treasury Stock (in shares)											1
Exercise of pre-funded warrants (in shares)					5,250
Fair value of warrants issued	(18,306)											(18,306)
Foreign currency translation	8
Exchange of warrants for common stock (in shares)					1,179
Net (loss) income	(19,222)															(19,222)
Total comprehensive loss	8																		8
Balance at Dec. 31, 2018	(14,939)											329,065				(344,054)			50
Balance (in shares) at Dec. 31, 2018					14,715		101
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation expense for issuance of stock options	273											273
Compensation expense for issuance of restricted stock	4											4
Compensation expense for issuance of restricted stock (in shares)					20
Shares issued due to fractional rounding upon reverse stock split					$ 1							(1)
Shares issued due to fractional rounding upon reverse stock split (in shares)					27,524
Issuance of Preferred Stock		$ 150	$ 29,536	$ 9,510									$ 150	$ 42,876	$ 14,408		$ (13,340)	$ (4,898)
Issuance of Preferred Stock (in shares)								15	32,572	9,510
Retirement of Series D Preferred Stock	(1,160)											(1,160)
Retirement of Series D Preferred Stock (in Shares)							(116)
Exercise of pre-funded warrants (in shares)						11,285
Fair value of warrants issued	(20,844)											(20,844)
Foreign currency translation	(22)
Exchange of warrants for Common Stock	$ 13											13
Exchange of warrants for common stock (in shares)	82,521				92
Conversion of Preferred stock into common stock	$ 1											1
Conversion of Preferred stock into common stock (in shares)					13,455		(565)
Net (loss) income	(8,879)															(8,879)
Total comprehensive loss	(22)																		(22)
Balance at Dec. 31, 2019	$ (6,357)				$ 1							$ 364,785				$ (371,171)			$ 28
Balance (in shares) at Dec. 31, 2019					67,091		41,517

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Deficit (Parenthetical)	Dec. 24, 2019	May 02, 2018
Statement Of Stockholders Equity [Abstract]
Reverse stock split	1:700	1:500
Reverse stock split ratio	0.00142	0.002

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (8,879)	$ (19,222)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock option compensation expense (income)	273	(40)
Restricted stock compensation expense	4	98
Depreciation expense	212	444
Amortization of Right of Use Asset	1,577	0
Warrant liability fair value adjustment	(17,493)	(19,706)
Non-cash interest income	(11)	(1)
Equitization of expenses	1,474	0
Loss on issuance of financial instrument	1,715	402
Interest expense accrued related to convertible notes	74	7,572
Debt discount amortization	4,467	2,826
Loss on debt settlements	0	1,123
Changes in assets and liabilities:
Prepaid expenses and other assets	(367)	(218)
Accounts receivable	497	(293)
Inventory	204	385
Accounts payable and accrued expenses	(4,791)	8,163
Deferred revenue	(479)	3,503
Interest payments on financing lease	(3)	0
Operating lease liability	(1,537)	0
Other non-current liabilities	(627)	232
Net cash used in operating activities	(23,690)	(14,732)
Cash flows from investing activities:
Purchase of property, plant and equipment	(24)	(76)
Net cash used in investing activities	(24)	(76)
Cash flows from financing activities:
Repayment of convertible note debt	0	(4,870)
Net proceeds from the issuance of debt	3,719	0
Principal payments of financing leases	(39)	0
Net proceeds from convertible note debt financing	0	5,664
Net proceeds from sale of stock	0	10,917
Net proceeds from exercise of warrants	0	520
Net cash provided by financing activities	30,305	13,236
Foreign currency effects on cash, cash equivalents and restricted cash	14	(174)
Net increase (decrease) in cash, cash equivalents and restricted cash	6,605	(1,746)
Cash, cash equivalents and restricted cash:
Beginning of period	3,578	5,324
End of period	10,183	3,578
Supplemental non-cash activities:
Fair value of warrants issued	20,844	28,539
Reclassification of Series D Warrants from liability to equity	0	4,210
Equitization of debt, interest and expenses into July 2019 Private Placement	12,572	0
Adoption of ASC 842 lease standard	1,652	0
Right of use assets obtained in exchange for lease obligations	874	0
Financing of insurance	548	0
Series E and E-1 Preferred Stock and Warrants [member]
Cash flows from financing activities:
Net proceeds from the sale of Series E and E-1 Preferred Stock and warrants	26,475	0
Series D Preferred Stock [Member]
Cash flows from financing activities:
Net proceeds from sale of Series D preferred shares	$ 150	$ 1,005

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Description of Business	(1) Description of Business Our primary research focus is on ocular melanoma liver metastases, or mOM, and intrahepatic cholangiocarcinoma, or ICC, a type of primary liver cancer, as well as certain other cancers that are metastatic to the liver. We believe that the disease states we are investigating are unmet medical needs that represent significant market opportunities. In the United States, Melphalan/HDS is considered a combination drug and device product and is regulated as a drug by the United States Food and Drug Administration, or the FDA. The FDA has granted us six orphan drug designations, including three orphan designations for the potential use of the drug melphalan for the treatment of patients with mOM, hepatocellular carcinoma and ICC. Melphalan/HDS has not been approved for sale in the United States. In Europe, our CHEMOSAT product is regulated as a Class IIb medical device and received its CE Mark in 2012. We are commercializing the CHEMOSAT system in select markets in the United Kingdom and the European Union, or EU, where we believe the prospect of securing reimbursement coverage for the use of CHEMOSAT is strongest. Liquidity and Going Concern The accompanying 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. As shown in the accompanying consolidated financial statements during the year ended December 31, 2019, the Company incurred net operating losses of $8.9 million and used $23.7 million of cash for its operating activities. These factors among others raise substantial doubt about the Company’s ability to continue as a going concern for a reasonable period of time. 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 us 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 our 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 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. At December 31, 2019, management believed that its capital resources were adequate to fund operations through June 2020. Additional working capital will be required to continue operations.

Basis of Consolidated Financial

Basis of Consolidated Financial Statement Presentation	12 Months Ended
	Dec. 31, 2019
Basis Of Condensed Consolidated Financial Statement Presentation [Abstract]
Basis of Consolidated Financial Statement Presentation	(2) Basis of Consolidated Financial Statement Presentation The accounting and financial reporting policies of the Company conform to generally accepted accounting principles in the United States of America (“GAAP”). The preparation of consolidated financial statements in conformity with GAAP requires management to make assumptions and estimates that impact the amounts reported in the Company’s consolidated financial statements. The consolidated financial statements include the accounts of all entities controlled by Delcath. All significant inter-company accounts and transactions are eliminated. Reverse Stock Splits All share numbers presented in these financial statements, including these footnotes reflect a one-for-five hundred (1:500)

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	(3) Summary of Significant Accounting Policies Use of Estimates The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. The amounts of assets and liabilities reported in the Company’s consolidated balance sheets and the amount of revenues and expenses reported for each of the periods presented are affected by estimates and assumptions, which are used for, but not limited to, the accounting for derivative instrument liabilities, stock-based compensation, valuation of inventory, impairment of long-lived assets, income taxes and operating expense accruals. Such assumptions and estimates are subject to change in the future as additional information becomes available or as circumstances are modified. Actual results could differ from these estimates. Cash Equivalents and Concentrations of Credit Risk The Company considers investments with original maturities of three months or less at date of acquisition to be cash equivalents. The Company has deposits that exceed amounts insured by the Federal Deposit Insurance Corporation (“FDIC”), however, the Company does not consider this a significant concentration of credit risk based on the strength of the financial institution. Restricted Cash Cash and cash equivalents that are restricted as to withdrawal or use under the terms of certain contractual agreements are recorded as restricted cash on the accompanying consolidated balance sheets. Accounts Receivable Accounts receivable, principally trade, are generally due within 30 days and are stated at amounts due from customers. Collections and payments from customers are monitored and a provision for estimated credit losses may be created based upon historical experience and specific customer collection issues that may be identified. Inventories Inventories are valued at the lower of cost or net realizable value using the first-in, first-out method. The reported net value of inventory includes finished saleable products, work-in-process, and raw materials that will be sold or used in future periods. The Company reserves for expired, obsolete, and slow-moving inventory. Property, Plant and Equipment Property, plant and equipment are recorded at cost, less accumulated depreciation. The Company provides for depreciation on a straight line basis over the estimated useful lives of the assets which range from three to seven years. Leasehold improvements will be amortized over the shorter of the lease term or the estimated useful life of the related assets when they are placed into service. The Company evaluates property, plant and equipment for impairment periodically to determine if changes in circumstances or the occurrence of events suggest the carrying value of the asset or asset group may not be recoverable. Derivative Instrument Liability The Company accounts for derivative instruments in accordance with Accounting Standards Codification (“ASC”) 815, Derivatives and Hedging, which establishes accounting and reporting standards for derivative instruments and hedging activities, including certain derivative instruments embedded in other financial instruments or contracts and requires recognition of all derivatives on the balance sheet at fair value, regardless of the hedging relationship designation. Accounting for changes in the fair value of the derivative instruments depends on whether the derivatives qualify as hedge relationships and the types of relationships designated are based on the exposures hedged. At December 31, 2019 and 2018, the Company did not have any derivative instruments that were designated as hedges. Fair Value Measurements The Company adheres to ASC 820, Fair Value Measurement, which defines fair value, establishes a framework for measuring fair value, and expands disclosures about fair value measurements. ASC 820 applies to reported balances that are required or permitted to be measured at fair value under existing accounting pronouncements; accordingly, the standard does not require any new fair value measurements of reported balances. ASC 820 emphasizes that fair value is a market-based measurement, not an entity-specific measurement. Therefore, a fair value measurement should be determined based on the assumptions that market participants would use in pricing the asset or liability. As a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a fair value hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity (observable inputs that are classified within Levels 1 and 2 of the hierarchy) and the reporting entity’s own assumptions about market participant assumptions (unobservable inputs classified within Level 3 of the hierarchy). • Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access. • Level 2 inputs are inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs may include quoted prices for similar assets and liabilities in active markets, as well as inputs that are observable for the asset or liability (other than quoted prices), such as interest rates, foreign exchange rates, and yield curves that are observable at commonly quoted intervals. • Level 3 inputs are unobservable inputs for the asset or liability, which is typically based on an entity’s own assumptions, as there is little, if any, related market activity. In instances where the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level input that is significant to the fair value measurement in its entirety. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability. Revenue Recognition Revenue is generated from proprietary and partnered product sales and license and royalty arrangements. Revenue is recognized when or as we transfer control of the promised goods or services to our customers in an amount that reflects the consideration to which we expect to be entitled to in exchange for those goods or services. When obligations or contingencies remain after the products are shipped, such as training and certifying the treatment centers, revenue is deferred until the obligations or contingencies are satisfied. We may enter into contracts with partners that contain multiple elements such as licensing, development, manufacturing and commercialization components. These arrangements are often complex and we may receive various types of consideration over the life of the arrangement, including: up-front fees, reimbursements for research and development services, milestone payments, payments on product shipments, margin sharing arrangements, license fees and royalties. Our results of operations for reporting periods beginning on or after January 1, 2018 are presented under ASC 606, Revenue from Contracts with Customers, while prior period amounts, as reported, are not adjusted. The effects of the adoption of the new standard in 2018 were not material to our consolidated financial statements. In assessing our revenue arrangements in accordance with ASC 606, Revenue from Contracts with Customers, we must identify the contract, determine the transaction price including an estimation of any variable consideration we expect to receive in connection with the contract, identify the promises of goods or services to the customer and each distinct performance obligation, allocate the transaction price to each of the performance obligations, and recognize revenue when or as the performance obligations are satisfied. Each of these steps in the revenue recognition process requires management to make judgements and/or estimates. The most significant judgements and estimates involve the determination of variable consideration to be included in the transaction price. Variable consideration is recognized at an amount we believe is not subject to significant reversal and is adjusted at each reporting period if the most likely amount of expected consideration changes or becomes fixed. We believe this provides a reasonable basis for recognizing revenue, however, actual results could differ from estimates and significant changes in estimates could impact our results of operations in future periods. Deferred Revenue License fees and milestones received in exchange for the grant of a license Selling, General and Administrative Selling, general and administrative costs include personnel costs and related expenses for the Company’s sales, marketing, general management and administrative staff, recruitment, costs related to the Company’s commercialization efforts in Europe, professional service fees, professional license fees, business development and certain general legal activities. All such costs are charged to expense when incurred. Research and Development Research and development costs include the costs of materials used for clinical trials and R&D, personnel costs associated with device and pharmaceutical R&D, clinical affairs, medical affairs, medical science liaisons, and regulatory affairs, costs of outside services and applicable indirect costs incurred in the development of the Company’s proprietary drug delivery system. All such costs are charged to expense when incurred. Stock Based Compensation The Company accounts for its share-based compensation in accordance with the provisions of ASC 718, Stock-Based Compensation, which establishes accounting for equity instruments exchanged for employee services and ASC 505-50, Equity-Based Payments to Non-Employees, which establishes accounting for equity-based payments to non-employees. Under the provisions of ASC 718, share-based compensation is measured at the grant date, based upon the fair value of the award, and is recognized as an expense over the option holders’ requisite service period (generally the vesting period of the equity grant). The Company is required to record compensation cost for all share-based payments granted to employees based upon the grant date fair value, estimated in accordance with the provisions of ASC 718. Under the provisions of ASC 505-50, measurement of compensation cost related to common shares issued to non-employees for services is based on the value of the services provided or the fair value of the shares issued. The measurement of non-employee stock-based compensation is subject to periodic adjustment as the underlying equity instrument vests. The Company expenses its share-based compensation for share-based payments granted under the accelerated method, which treats each vesting tranche as if it were an individual grant. The Company periodically grants stock options for a fixed number of shares of common stock to its employees, directors and non-employee contractors, with an exercise price greater than or equal to the fair market value of Delcath’s common stock at the date of the grant. The Company estimates the fair value of stock options using an option pricing model. Key inputs used to estimate the fair value of stock options include the exercise price of the award, the expected post-vesting option life, the expected volatility of Delcath’s stock over the option’s expected term, the risk-free interest rate over the option’s expected term, and Delcath’s expected annual dividend yield. Estimates of fair value are not intended to predict actual future events or the value ultimately realized by persons who receive equity awards. Income Taxes The Company accounts for income taxes following the asset and liability method in accordance with the ASC 740, Income Taxes. Under such method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the consolidated financial statement carrying amounts of existing assets and liabilities and their respective tax bases. The Company applies the accounting guidance issued to address the accounting for uncertain tax positions. This guidance clarifies the accounting for income taxes, by prescribing a minimum recognition threshold a tax position is required to meet before being recognized in the financial statements as well as provides guidance on derecognition, measurement, classification, interest and penalties, accounting in interim periods, disclosure and transition. The Company classifies interest and penalty expense related to uncertain tax positions as a component of income tax expense. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years that the asset is expected to be recovered or the liability settled. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. The ultimate realization of deferred tax assets depends on the generation of future taxable income during the period in which related temporary differences become deductible. The Company considers the scheduled reversal of deferred tax liabilities, projected future taxable income and tax planning strategies in its assessment of a valuation allowance. See Note 14 for additional information. Net Loss per Common Share Basic net loss per share is determined by dividing net loss by the weighted average shares of common stock outstanding during the period, without consideration of potentially dilutive securities except for those shares that are issuable for little or no cash consideration. Diluted net loss per share is determined by dividing net loss by diluted weighted average shares outstanding. Diluted weighted average shares reflects the dilutive effect, if any, of potentially dilutive common shares, such as stock options and warrants calculated using the treasury stock method. In periods with reported net operating losses, all common stock options and warrants are generally deemed anti-dilutive such that basic net loss per share and diluted net loss per share are equal. However, in certain periods in which the exercise price of the warrants was less than the last reported sales price of Delcath’s common stock on the final trading day of the period and there is a gain recorded pursuant to the change in fair value of the warrant derivative liability, the impact of gains related to the mark-to-market adjustment of the warrants outstanding at the end of the period is reversed and the treasury stock method is used to determine diluted earnings per share. As discussed in Note 11, the Series E Preferred Stock and the Series E-1 Preferred Stock were each determined to have a beneficial conversion feature which was accounted for as a deemed dividend. For the years ended December 31, 2019 and 2018 the following potentially dilutive securities were excluded from the computation of diluted earnings per share because their effects would be antidilutive: 2019 2018 Common stock warrants - equity — 6,005 Common stock warrants - liability 1,826,608 271 Assumed conversion of Series E and Series E-1 Preferred Stock 1,802,008 — Assumed conversion of convertible notes 63,493 3,681 Stock options 1,640 — Total 3,693,749 9,957 Segment Information The Company currently operates in one business segment, which is the development and commercialization of Melphalan/HDS and CHEMOSAT. A single management team that reports to the CEO and President comprehensively manages the business. Accordingly, the Company does not have separately reportable segments. Foreign Currency and Currency Translation Transactions that are denominated in a foreign currency are remeasured into the functional currency at the current exchange rate on the date of the transaction. Any foreign currency-denominated monetary assets and liabilities are subsequently remeasured at current exchange rates, with gains or losses recognized as foreign exchange (losses)/gains in the statements of operations. The assets and liabilities of the Company’s international subsidiaries are translated from their functional currencies into United States dollars at exchange rates prevailing at the balance sheet date. The majority of the foreign subsidiaries revenues and operating expenses are denominated in Euros. The reporting currency for the Company is the United States Dollar (“USD”). Average rates of exchange during the period are used to translate the statement of operations, while historical rates of exchange are used to translate any equity transactions. Translation adjustments arising on consolidation due to differences between average rates and balance sheet rates, as well as unrealized foreign exchange gains or losses arising from translation of intercompany loans that are of a long-term-investment nature, are recorded in other comprehensive income. 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 Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842) Codification Improvements to Topic 842, Leases Leases (Topic 842)—Targeted Improvements Leases The Company has elected certain practical expedients permitted under the transition guidance within ASC 842 to leases that commenced before January 1, 2019, including the package of practical expedients. The election of the package of practical expedients resulted in the Company not reassessing prior conclusions under ASC 840 related to lease identification, lease classification and initial direct costs for expired and existing leases prior to January 1, 2019. The Company did not elect the practical expedient to not record short-term leases on its consolidated balance sheet. The adoption of ASU 2016-02 did not have a significant impact on the Company’s consolidated results of operations or cash flows. See Note 9 for additional information. SEC Disclosure Update and Simplification In August 2018, the SEC adopted the final rule under SEC Release No. 33-10532, Disclosure Update and Simplification, amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders' equity for interim financial statements. Under the amendments, an analysis of changes in each caption of stockholders' equity presented in the balance sheet must be provided in a note or separate statement. The analysis should present a reconciliation of the beginning balance to the ending balance of each period for which a statement of comprehensive income is required to be filed. This final rule was effective on November 5, 2018. The adoption did not have a material impact on the Company’s consolidated financial statements.

Restricted Cash

Restricted Cash	12 Months Ended
	Dec. 31, 2019
Restricted Cash [Abstract]
Restricted Cash	( 4 ) Restricted Cash Cash and cash equivalents that are restricted as to withdrawal or use under the terms of certain contractual agreements are recorded in Restricted Cash (in thousands) December 31, 2019 December 31, 2018 Cash and cash equivalents $ 10,002 $ 2,516 Convertible Notes — — Letters of credit 131 1,012 Security for credit cards 50 50 Total cash, cash equivalents and restricted cash shown in the statement of cash flows $ 10,183 $ 3,578

Inventories

Inventories	12 Months Ended
	Dec. 31, 2019
Inventory Disclosure [Abstract]
Inventories	( 5 ) Inventories Inventories consist of: (in thousands) December 31, 2019 December 31, 2018 Raw materials $ 375 $ 358 Work-in-process 279 500 Finished goods — — Total Inventory $ 654 $ 858

Prepaid Expenses and Other Curr

Prepaid Expenses and Other Current Assets	12 Months Ended
	Dec. 31, 2019
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Prepaid Expenses And Other Current Assets	( 6 ) Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets include the following: (in thousands) December 31, 2019 December 31, 2018 Clinical trial expenses 725 — Insurance premiums 589 140 Security deposit 51 51 Income tax and VAT receivable 31 579 Other 1 363 128 Total prepaid expenses and other current assets $ 1,759 $ 898 1

Property, Plant, and Equipment

Property, Plant, and Equipment	12 Months Ended
	Dec. 31, 2019
Property Plant And Equipment [Abstract]
Property, Plant, and Equipment	( 7 ) Property, Plant, and Equipment Property, plant, and equipment consists of: (in thousands) December 31, 2019 December 31, 2018 Estimated Useful Life Buildings and land $ 589 $ 589 30 years - Buildings Enterprise hardware and software 1,739 1,742 3 years Leaseholds 1,695 1,701 Lesser of lease term or estimated useful life Equipment 1,025 1,002 7 years Furniture 198 198 5 years Property, plant and equipment, gross 5,246 5,232 Accumulated depreciation (4,511 ) (4,307 ) Property, plant and equipment, net $ 735 $ 925 Depreciation expense for the years ended December 31, 2019 and 2018 was $0.2 million and $0.4 million, respectively.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued Expenses	( 8 ) Accrued Expenses Current accrued expenses include the following: (in thousands) December 31, 2019 December 31, 2018 Clinical trial expenses $ 2,497 $ 4,530 Compensation, excluding taxes 3,525 1,785 Professional fees 263 190 Short-term portion of lease restructuring - 184 Other 1 662 1,275 Total accrued expenses $ 6,947 $ 7,964 1

Leases

Leases	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Leases	( 9 ) Leases The Company recognizes right-of-use (“ROU”) assets and lease liabilities when it obtains the right to control an asset under a leasing arrangement with an initial term greater than twelve months. The Company leases its facilities under non-cancellable operating and financing leases. The Company evaluates the nature of each lease at the inception of an arrangement to determine whether it is an operating or financing lease and recognizes the ROU asset and lease liabilities based on the present value of future minimum lease payments over the expected lease term. The Company’s leases do not generally contain an implicit interest rate and therefore the Company uses the incremental borrowing rate it would expect to pay to borrow on a similar collateralized basis over a similar term in order to determine the present value of its lease payments. The following table summarizes the Company’s operating and financing leases as of December 31, 2019: (in thousands) US Ireland Total Lease Cost Operating lease cost $ 710 $ 210 $ 920 Financing lease cost 42 — 42 Sublease income (215 ) (175 ) (390 ) Total $ 537 $ 35 $ 572 Other information Operating cash flows out from operating leases (755 ) (210 ) (965 ) Operating cash flows in from operating leases 215 175 390 Operating cash flows out from financing leases (39 ) — (39 ) Right-of-use assets exchanged for new operating lease liabilities 874 — 874 Weighted average remaining lease term 1.1 1.8 Weighted average discount rate - operating leases 8 % 8 % Maturities of the Company’s operating leases, excluding short-term leases, are as follows: (in thousands) US Ireland Total Year ended December 31, 2020 $ 498 $ 210 $ 708 Year ended December 31, 2021 79 122 201 Total 577 332 909 Less present value discount (27 ) (21 ) (48 ) Operating lease liabilities included in the condensed consolidated balance sheet at December 31, 2019 $ 550 $ 311 $ 861

Outstanding Debt

Outstanding Debt	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Outstanding Debt	( 10 ) Outstanding Debt On June 6, 2019, the Company entered into an agreement with two institutional investors, pursuant to which the investors agreed to transfer and surrender warrants to purchase 5,605 shares of the Company’s common stock (the “Series D Warrants”) and warrants to purchase 0.1 million shares of the Company’s common stock (the “Pre-Funded Series D Warrants”) for cancellation by the Company. Under the terms of the Purchase Agreement, the Company agreed to sell and issue to the investors 8% Senior Secured Promissory Notes in an aggregate principal amount of $2.0 million in full payment and satisfaction of the purchase price for the Series D Warrants and Pre-Funded Series D Warrants. This agreement was effective on July 15, 2019, upon the closing of the Company’s Private Placement discussed further in Note 11. Following the closing of the Private Placement, the Company entered into an agreement under which the 8% Senior Secured Promissory Notes became convertible into shares of Series E Preferred Stock and Warrants at the price of $1,500 per Unit. The principal is recognized in Convertible notes payable, long-term on the consolidated balance sheet. On April 19, 2019, April 26, 2019, May 9, 2019 and May 23, 2019, the Company issued 8% senior secured notes (collectively, the “2019 Notes”) in the aggregate principal amount of $3.3 million, to two institutional investors. The 2019 Notes bore interest at the rate of 8% per annum and were to mature on the six-month anniversary of issuance in each case. The 2019 Notes were not convertible. The 2019 Notes contained standard events of default and remedies and are secured by a lien on the Company’s assets. The 2019 Notes were exchanged as part of the recent equity financing discussed further in Note 11 and are no longer outstanding. In March 2019, the Company exchanged all issued and outstanding shares of its Series D Preferred Stock (having an aggregate stated value of $1,160,000) and received $400,000 in cash proceeds in exchange for a senior secured promissory note (the “March 2019 Note”) in the principal amount of $1,560,000. The March 2019 Note bore interest at the rate of 8% per annum, and were to mature on April 1, 2020, and was not convertible. The March 2019 Note was exchanged as part of the recent equity financing discussed further in Note 9 and is no longer outstanding. On June 4, 2018, July 21, 2018, August 29, 2018, and September 21, 2018, the Company issued 8% senior secured convertible notes (collectively, the “2018 Notes”) in the aggregate principal amount of $9.4 million to several institutional investors. The 2018 Notes bore interest at the rate of 8% per annum and had maturity dates between December 2018 and March 2021. The 2018 Notes were initially convertible and secured pursuant to a Security Agreement which created a first priority security interest in all of the personal property (other than Excluded Collateral as defined in the Security Agreement) of the Company of every kind and description, tangible or intangible, whether currently owned and existing or created or acquired in the future. In March 2019, the Company amended the June 2018, July 2018 and August 2018 Notes to make them non-convertible. There was no impact to the financial statements. In April 2019, the Company received notices of default from the investors in the 2018 Notes which resulted in a 25%, or $1.1 million, increase in principal and an increase in the interest rates from 8% to 18%. The 2018 Notes were exchanged as part of the recent equity financing discussed further in Note 9 and are no longer outstanding. The following table provide a summary of the outstanding Note at December 31, 2019 : (in millions) Conversion price Current interest rate Principal Long term convertible notes payable 8.0% July 2019 Notes $ 1,500 8 % $ 2.0 The following table provides a summary of the Notes by their maturity dates (absent provisions of default) at December 31, 2018: (in millions) Interest rate Conversion price Principal Unamortized Discount Carrying value December 4, 2018 8.0% $ 1.75 $ 1.7 $ — $ 1.7 March 1, 2019 8.0% 1.75 0.6 (0.5 ) 0.1 March 21, 2019 8.0% 1.75 0.4 (0.2 ) 0.2 December 4, 2019 8.0% 1.75 0.9 (0.9 ) — March 1, 2020 8.0% 1.75 0.8 (0.8 ) — March 21, 2020 8.0% 1.75 0.1 (0.1 ) — Total Convertible Notes Payable, net $ 4.5 $ (2.5 ) $ 2.0

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2019
Stockholders Equity Note [Abstract]
Stockholders' Equity	(1 1 ) Stockholders’ Equity Preferred Stock Issuances Series E and Series E-1 Preferred Stock On July 11, 2019, the Company entered into a securities purchase agreement with certain accredited investors pursuant to which Delcath sold to investors an aggregate of 20,000 shares of our Series E convertible preferred stock, par value $0.01 per share, or the Series E Preferred Stock, at a price of $1,000 per share and a warrant, or a 2019 E Warrant, to purchase a number of shares of common stock equal to the number of shares of common stock issuable upon conversion of the Series E Preferred Stock purchased by the investor, or the July 2019 Private Placement. In connection with the July 2019 Private Placement, the Company exchanged $11.8 million of debt, interest and Series D Warrants for 11,500 shares of Series E Preferred Stock and related 2019 Warrants, $0.1 million in accounts payables for 149 shares of Series E Preferred Stock and related 2019 Warrants and issued 923 shares of Series E Preferred Stock and related 2019 Warrants to certain investors in exchange for a waiver of rights under exchange agreements signed in December 2018 and March 2019, or the Debt Exchange. On August 19, 2019, the Company entered into a securities purchase agreement with certain accredited investors pursuant to which Delcath sold to investors an aggregate of 9,510 shares of Series E-1 convertible preferred stock, par value $0.01 per share, or the Series E-1 Preferred Stock, at a price of $1,000 per share and a warrant, or a 2019 E-1 Warrant, and together with the 2019 E Warrant, the 2019 Warrants, to purchase a number of shares of common stock of the Company equal to the number of shares of common stock issuable upon conversion of the Series E-1 Preferred Stock purchased by the investor, or the August 2019 Private Placement, and, collectively with the July 2019 Private Placement, the Private Placements. Each share of Series E Preferred Stock and Series E-1 Preferred Stock, or, collectively, the Preferred Stock, was originally convertible at any time at the option of the holder into the number of shares of common stock determined by dividing the stated value by the conversion price of $42.00, subject to certain limitations and adjustments, or the Conversion Price. Except for certain adjustments, the holders of the Preferred Stock are entitled to receive dividends on shares of Preferred Stock equal (on an “as converted” basis) to and in the same form as dividends paid on shares of the common stock. Any such dividends that are not paid to the holders of the Preferred Stock will increase the stated value. No other dividends will be paid on shares of Preferred Stock. Each 2019 Warrant had an original exercise price equal to $42.00, subject to adjustment in accordance with the terms of the 2019 Warrants, or the Exercise Price, and became exercisable at any time upon the consummation of the Reverse Split and will be exercisable until 5:00 p.m. (NYC time) on the date that is five years following the date of the Reverse Split. Pursuant to the terms of the Preferred Stock and the 2019 Warrants, the Conversion Price of the Preferred Stock and the Exercise Price of the 2019 Warrants were initially subject to adjustment in each of the following circumstances: (i) on the third trading day following the date that the Company effects a reverse stock split, or the Reverse Split Reset Date, (ii) the date that the initial registration statement covering the shares of common stock issuable upon the conversion of the Preferred Stock and the exercise of the 2019 Warrants is declared effective by the SEC, or the Registration Reset Date, and (iii) in the event that all of the shares of common stock which we were required to register with the SEC were not then registered on an effective registration statement, the date that all of the shares underlying the respective Preferred Stock and 2019 Warrants may be sold pursuant to Rule 144, or the Rule 144 Reset Date, each of such reset dates, a Reset Date and, collectively, the Reset Dates. On each Reset Date, the Conversion Price and the Exercise Price were to be reduced, and only reduced, to equal the lesser of (x) the then effective Conversion Price or Exercise Price, as applicable, and (y) 90% of the average of the five daily volume weighted average prices of the common stock immediately prior to each Reset Date, or the Reset Formula. In the event of a reduction in the Exercise Price, the aggregate number of Warrant Shares issuable upon the exercise of the 2019 Warrants were to be increased such that the aggregate Exercise Price of the Warrants on the day immediately following such Reset Date equaled the aggregate Exercise Price immediately prior to such adjustment. In addition, from the date of issuance of the Preferred Stock and Warrants until such time that the Company’s common stock is listed or quoted on a national exchange, the Conversion Price and the Exercise Price are subject to price-based anti-dilution protections. The Registration Reset Date occurred on November 7, 2019. However, pursuant to the Reset Formula, no reduction in the Conversion Price or the Exercise Price occurred on the Registration Reset Date. The Reverse Split Reset Date occurred on December 30, 2019. Pursuant to the Reset Formula, the Conversion Price and the Exercise Price were reduced to $23.04 per share as of the Reverse Split Reset Date. The Rule 144 Reset Date with respect to the Series E Preferred Stock and the Series E Warrants occurred on January 15, 2020, but no reset in the Conversion Price or the Exercise Price of the Series E Preferred Stock or the Series E Warrants occurred as of such date because all of the shares of common stock issuable in respect of such securities had been registered for resale. The Rule 144 Reset Date with respect to the Series E-1 Preferred Stock and the Series E-1 Warrants occurred on February 19, 2020, but no reset in the Conversion Price or the Exercise Price of the Series E-1 Preferred Stock or the Series E-1 Warrants occurred as of such date because all of the shares of common stock issuable in respect of such securities had been registered for resale. As a consequence of the reduction of the Conversion Price on the Reverse Split Reset Date, an additional 813,473 shares of common stock became issuable upon the conversion of the Preferred Stock and, as a consequence of the reduction of the Exercise Price on the Reverse Split Reset Date, an additional 824,587 shares of common stock became issuable upon the exercise of the 2019 Warrants, or collectively the Reset Shares. Pursuant to the terms of the registration rights agreements entered into in connection with the Private Placements and the Debt Exchange we were required to register a number of shares of our common stock that would be issuable assuming that the Conversion Price and the Exercise Price were $16.10 per share, regardless of the actual Conversion Price or the Exercise Price. Pursuant to that requirement, we registered a total of 3,429,680 shares of common stock for sale or other disposition by the Selling Stockholders on our registration statement on Form S-1 (File No. 333-235751), or the Second Registration Statement, which included the Rosalind Shares, the Reset Shares and an additional 1,564,085 shares of our common stock, or the Registrable Shares, even though we were obligated to issue only the Reset Shares as a result of the Reverse Split. However, because the Second Registration Statement was not declared effective until January 7, 2020, the Company is liable to Rosalind for liquidated damages under the terms of the registration rights agreements relating to the Private Placements and the Debt Exchange for the period from December 28, 2019 and January 7, 2020. The Company received net proceeds after expenses of $26.6 million. As discussed above, the Company exchanged $11.8 million of debt, interest and Series D Warrants for 11,500 shares of Series E Preferred Stock and related warrants. The Company also exchanged $0.1 million in accounts payables for 149 shares of Series E Preferred Stock and related warrants and issued 923 shares of Series E Preferred Stock and related Warrants to certain investors in exchange for a waiver of rights under exchange agreements signed in December 2018 and March 2019. Of the net proceeds and equitized value received, the Company allocated an estimated fair value of $20.8 million to the 2019 Warrants. As a result of the Series E Preferred Stock and Series E-1 Preferred Stock having an effective conversion price that was lower than the market price on the date of issuance, the Company has recognized a beneficial conversion feature of $18.3 million. Due to the Series E Preferred Stock and Series E-1 Preferred Stock being immediately convertible, the beneficial conversion feature was recognized in full as a deemed dividend. Series D Preferred Stock On November 5, 2018, the Company’s Board authorized the establishment of a new series of preferred stock designated as Series D Preferred Stock, $0.01 par value, the terms of which are set forth in the certificate of designations for such series of Preferred Stock. On March 29, 2019, the Company exchanged all issued and outstanding shares of its Series D Preferred Stock (having an aggregate stated value of $1,160,000) and received $400,000 in cash proceeds in exchange for the issuance of the March 2019 Notes. Please see the discussion under Notes 10 and 11 above. Common Stock Issuances Series E and Series E-1 Convertible Preferred Stock Conversions 565 shares of Series E and Series E-1 Convertible Preferred Stock were converted into 13,455 shares of common stock, $0.01 par value per share, during 2019. Pre-Funded Series D Warrant Exercises 5,379 Pre-Funded Series D Warrants were exercised during 2018. December 2018 Warrant Exchange In December 2018, the Company entered into exchange agreements with several institutional investors with respect to their November 2017 Warrants and February 2018 Warrants. The Company issued to the investors 1,179 shares of Common Stock (the “Exchange Shares”) in exchange for the Existing Warrants (the “Exchange”). The Exchange was made in reliance upon the exemption from registration provided by Section 3(a)(9) of the Securities Act of 1933, as amended. September 2018 Rights Offering In September 2018, the Company completed the sale of 6,669 shares of its common stock, with net proceeds after expenses of approximately $7.0 million. The rights offering was made pursuant to a Registration Statement on Form S-1 that was made effective on August 3, 2018. February 2018 Financing In February 2018, the Company completed the sale of 606 shares of its Common Stock, 109 pre-funded warrants and the issuance of warrants to purchase 1,429 common shares (the “February 2018 Warrants”) pursuant to a placement agent agreement, with net proceeds after expenses of $4.3 million. The February 2018 Warrants are exercisable one year after the anniversary date of their issuance. At December 31, 2018, the February 2018 Warrants were exercisable at $7,000 per share with 273 warrants outstanding. The Company allocated an estimated fair value of $18.3 million to the February 2018 Warrants. The Company valued the February 2018 Warrants using the following inputs: exercise price of $7,000; contractual term of six years; volatility of 122.68% and risk-free rate of approximately one percent. Due to certain price protection features in the agreement, the February 2018 Warrants were accounted for as a derivative liability at issuance and will be subsequently marked to market through the statement of operations. In October 2018, the Company filed a registration statement on Form S-3 with the SEC, which was declared effective on December 21, 2018 and allows the Company to offer and sell, from time to time in one or more offerings, up to $100.0 million of common stock, preferred stock, warrants, debt securities and stock purchase contracts as it deems prudent or necessary to raise capital at a later date. The Company has lost its Form S-3 eligibility due to the late filing of its Form 10-K for the year ended December 31, 2018. Absent prior relief from the SEC, we expect to regain S-3 eligibility on June 1, 2020. Stock Incentive Plans The Company’s 2019 Equity Incentive Plan (the “Plan”) allows for grants in the form of incentive stock options, nonqualified stock options, stock units, stock awards, stock appreciation rights, and other stock-based awards. All of the Company’s officers, directors, employees, consultants and advisors are eligible to receive grants under the Plan. The maximum number of shares reserved for issuance under the Plan is 2,142. Options to purchase shares of common stock are granted at exercise prices not less than 100% of fair value on the dates of grant. As of December 31, 2019, the Plan had approximately 502 shares available for grant. The following is a summary of stock option activity under the Plan for the year ended December 31, 2019: Number of Shares Weighted Average Exercise Price Weighted Remaining Contractual Term (Years) Aggregate Intrinsic Value Outstanding at January 1, 2019 — Granted 1,782 $ 196.70 Exercised — Cancelled/Forfeited (142 ) $ 196.70 Outstanding at December 31, 2019 1,640 $ 196.70 9.1 $ — Exercisable at December 31, 2019 1,502 $ 196.70 9.1 $ — At December 31, 2019, there was approximately $25,000 of total unrecognized compensation expense related to non-vested share-based compensation awards under the plans for employee and board stock option grants. The cost is expected to be recognized over a weighted average period of 0.1 year. For the years ended December 31, 2019 and 2018, the Company recognized compensation expense $0.3 million and compensation income of $0.04 million, respectively, related to stock options granted to employees and board members. For the year ended December 31, 2019 the Company did not recognize any restricted stock compensation expense. For the year ended December 31, 2018, the Company recognized compensation expense of approximately $0.1 million related to restricted stock granted to employees and consultants. (in thousands) Twelve months ended December 31, 2019 Twelve months ended December 31, 2018 Selling, general and administrative $ 213,807 $ 120,850 Research and development 59,391 (61,867 ) Total $ 273,198 $ 58,983 Warrants The following is a summary of warrant activity for the years ended December 31, 2019 and 2018: Warrants Exercise Share Weighted Exercise Price Weighted Average Remaining (Years) Outstanding at January 1, 2018 20 $857,500 - $13,798,400,000 $ 4,868,205,366 4.88 Warrants issued 100,352 222 Warrants exercised (6,536 ) 1,252 Warrants expired (1 ) 13,798,400,000 Outstanding at December 31, 2018 93,835 $7 - $7,000 $ 151 5.75 Warrants issued 1,826,579 42 Warrants exercised (11,285 ) 7 Warrants exchanged (82,521 ) 170 Outstanding at December 31, 2019 1,826,608 $7 - $23 $ 23 4.99

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	(1 2 ) Fair Value Measurements The table below presents the activity within Level 3 of the fair value hierarchy for the twelve months ended December 31, 2019: Fair Value Measurements Using Significant Unobservable Inputs (Level 3) (in thousands) Warrant Liability Balance at January 1, 2018 $ 560 Fair value of warrants issued 23,533 Total change in the liability included in earnings (19,706 ) Reclass from liability to equity (4,210 ) Fair value of warrants exchanged (144 ) Balance at December 31, 2018 33 Total change in the liability included in earnings (17,498 ) Reclass from liability to equity (11 ) Fair value of warrants issued 20,844 Balance at December 31, 2019 3,368 At December 31, 2018, the Company had a total of 179 February 2018 Warrants outstanding, which were surrendered pursuant to a settlement agreement entered into between the Company and the holders of the February 2018 Warrants on April 18, 2019 and final payment under the settlement was made on July 16, 2019. The fair value of the Warrants at December 31, 2019 was determined by using option pricing models assuming the following: December 31, December 31, 2019 2018 Expected life (in years) 4.6 1.1 - 5.1 Expected volatility 207.5% 145.7% - 265.3% Risk-free interest rates 1.7% 2.5% - 2.6% The table below presents the Company’s assets and liabilities measured at fair value on a recurring basis as of December 31, 2019 and 2018, aggregated by the level in the fair value hierarchy within which those measurements fall. Assets and Liabilities Measured at Fair Value on a Recurring Basis Assets and Liabilities Measured at Fair Value on a Recurring Basis Level 1 Level 2 Level 3 Balance at December 31, (in thousands) 2019 2018 2019 2018 2019 2018 2019 2018 Liabilities Derivative instrument liabilities $ — $ — $ — $ — $ 3,368 $ 33 $ 3,368 $ 33 For the twelve months ended December 31, 2019 and 2018 there were no transfers in or out of Level 1, 2 or 3 inputs.

Commitments

Commitments	12 Months Ended
	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments	(13) Commitments Financing Lease In January 2019, the Company entered into an amendment (the “Park Road Lease Amendment”) to a lease agreement entered into in October 2018 (the “Park Road Lease”) for approximately 6,000 square feet of space located at 95-97 Park Road in Queensbury, New York. Under the terms of the Park Road Lease Amendment, the original two year term which began on October 31, 2018 was extended through November 2020 and provides for total annual base rent of $50,000 per year. Operating Leases In September 2018, the Company entered into an amendment (the “1633 Sublease Amendment”) to a sub-lease agreement executed in March 2016 (the “1633 Sublease) for approximately 6,877 square feet of office space at 1633 Broadway, New York, NY. The term began in April 2016 and under the terms of the 1633 Sublease Amendment is extended through February 2021 and provides for total annual base rent of $0.5 million. In August 2011, Delcath Systems Ltd. entered into an agreement of lease for an office and manufacturing facility located in the city of Galway, Ireland. This facility is approximately 19,200 square feet and is intended to be the location of Delcath’s European headquarters. The Lease is for a term of ten years, commencing August, 2011. The Lease provides for fixed annual lease amounts payable in advance in equal quarterly installments. The remaining annual lease amount is $0.2 million. Delcath Systems Ltd. is also required to pay for customary building operating expenses. Delcath Systems Ltd.’s payment obligations and performance of the Lease are guaranteed by Delcath. The Company has sub-leased a portion of this facility. Future minimum lease payments, net of receipts due under the terms of subleases, under all operating leases at December 31, 2019 are as follows: (in thousands) Future Lease Payments 2020 635 2021 79 $ 714 For the years ended December 31, 2019 and 2018 rent expense, net of receipts under the terms of subleases, totaled approximately $0.5 million and $0.6 million, respectively. Letters of Credit Under the terms of a sub-lease agreement for office space at 1633 Broadway, New York, NY, the Company is required to maintain a letter of credit in the amount of $0.1 million which will expire with the sublease in February 2021.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	(1 4 ) Income Taxes There is no income tax expense recognized for the years ended December 31, 2019 and 2018, respectively. Loss before taxes consists of: (in thousands) December 31, 2019 December 31, 2018 Domestic $ (4,882 ) $ (12,961 ) Foreign (3,997 ) (6,261 ) Income (loss) before taxes $ (8,879 ) $ (19,222 ) The provision for income taxes differs from the amount computed by applying the statutory rate as follows: (in thousands) December 31, 2019 December 31, 2018 Income taxes using U.S federal statutory rate $ (1,865 ) $ (4,037 ) Tax Cuts and Jobs Act — — Nondeductible interest 994 2,273 Loss on extinguishment of debt 361 236 Loss of tax benefit of federal net operating loss carryforwards — (588 ) Loss of tax benefit of state net operating loss carryforwards 1,477 1,040 Loss of tax benefit of federal tax credit carryforwards 324 495 Amortization of gain on IP migration — — State income taxes, net of federal benefit (1,461 ) (2,355 ) Foreign rate differential 664 1,166 Valuation allowance 3,512 6,323 Derivative charge (3,674 ) (4,138 ) Stock option exercises and cancellations — 215 Research and development costs (316 ) (636 ) Other (16 ) 6 $ — $ — Significant components of the Company’s deferred tax assets are as follows: (in thousands) December 31, 2019 December 31, 2018 Deferred tax assets: Equity compensation $ 84 $ — Accrued liabilities — 519 Research tax credits 135 161 Lease obligation 206 Other 72 60 Net operating losses 14,502 10,624 Total deferred tax assets $ 14,999 $ 11,364 Deferred tax liabilities: Beneficial conversion feature — — Right of use asset 206 — Other — — Total deferred tax liabilities 206 — Valuation allowance 14,793 11,364 Net deferred tax assets $ — $ — As of December 31, 2019 and 2018 the Company had net operating loss carryforwards for U.S. federal income tax purposes of approximately $246.3 million and $230.0 million, respectively. A significant portion of the federal amount is subject to an annual limitation as low as $27,500 as a result of changes in the Company’s ownership in May 2003, November 2016, and multiple dates throughout 2017, 2018 and 2019, as defined by Federal Internal Revenue Code Section 382 and the related income tax regulations. As a result of the limitations caused by the May 2003, November 2016 and multiple 2017, 2018 and 2019 ownership changes, approximately $207.0 million of the total net operating loss carryforwards is expected to expire unutilized and will be unavailable to offset future federal taxable income. Approximately $39.3 million of net operating loss carryforwards remains available to offset future federal taxable income, of which $1.7 million will expire between 2020 and 2037 and $37.6 million will have an unlimited carryforward period as a result of the Tax Cuts and Jobs Act. In addition, the Company’s state net operating losses are also subject to annual limitations that generally follow the federal Section 382 provisions (with the exception of Connecticut), adjusted for each state’s respective income apportionment percentages. As of December 31, 2019 and 2018, the Company had net operating loss carryforwards for state and city income tax purposes between approximately $27.3 million and $180.6 million and between approximately $27.3 million and $167.3 million, respectively, which expire through 2039. As a result of the 382 limitations, approximately $169.4 million and $153.7 million of New York State and New York City net operating losses are expected to expire unutilized and will be unavailable to offset future taxable income. Approximately $11.2 million and $11.2 million of net operating loss carryforwards, respectively, will be available to offset future state and city taxable income. As of December 31, 2019 and 2018 the Company had a net operating loss carryforward for foreign income tax purposes of $26.1 million and $25.2 million, respectively, which have indefinite carryforward periods. As of December 31, 2019 and 2018, the Company had federal research and development tax credit carryforwards of approximately $5.3 million and $5.0 million respectively, which expire through 2039. As a result of the section 382 limitations, all but $0.1 million of the tax credit carryforwards is expected to expire unutilized. Management has established a 100% valuation allowance against the deferred tax assets as management does not believe it is more likely than not that these assets will be realized. The Company’s valuation allowance increased by approximately $3.4 million and increased by $5.4 million in 2019 and 2018, respectively. The change in valuation is as follows: (in thousands) December 31, 2019 December 31, 2018 Beginning balance $ 11,364 $ 5,972 Charged to costs and expenses 3,512 6,323 Charged to additional paid-in capital — — Charged to retained earnings — (834 ) Charged to other comprehensive income (83 ) (97 ) Ending balance $ 14,793 $ 11,364 On December 22, 2017, the United States enacted the Tax Cuts and Jobs Act (the “Act”). The Act, which is also commonly referred to as “U.S. tax reform”, significantly changes U.S. corporate income tax laws by, among other provisions, reducing the maximum U.S. corporate income tax rate from 35% to 21% starting in 2018. During the year ended December 31, 2017, the Company reduced deferred tax assets by a provisional amount of $143,500, offset by a corresponding reduction to its valuation allowance, as a result of the re-measurement of deferred tax assets and liabilities from its 34% effective rate under existing law to the new lower statutory rate of 21%. The Company finalized its accounting of the effects of tax reform in 2018, which resulted in insignificant adjustments. The Act also requires a mandatory one-time inclusion of the deferred foreign income of controlled foreign corporations. The one-time transition tax is based on Delcath’s total post-1986 earnings and profits (E&P) for which the Company has previously deferred from U.S. income taxes. During the year ended December 31, 2017, the Company’s reasonable estimate resulted in no provisional amount for the one-time transition tax liability, as the Company’s international subsidiaries are expected to have a cumulative deficit in E&P. As the Company’s international subsidiaries have a cumulative deficit in earnings and profits, the Company did not anticipate being affected by the mandatory inclusion provisions of the Act. The Company finalized its calculation of the total post-1986 foreign E&P (including deficits) for these foreign subsidiaries during 2018 and was not impacted by the mandatory inclusion provisions of the Act. On December 22, 2017, Staff Accounting Bulletin 118 was issued due to the complexities involved in accounting for the recently enacted Act. SAB 118 requires the Company to include in its financial statements a reasonable estimate of the impact of the Act on earnings to the extent such estimate has been determined. Accordingly, the U.S. provision for income tax for December 31, 2017 was based on the reasonable estimate guidance provided by SAB 118. The Company finalized the impact from the Act during 2018 and recorded insignificant adjustments. The Company complies with the provisions of ASC 740-10, Income Taxes, in accounting for its uncertain tax positions. ASC 740-10 addresses the determination of whether tax benefits claimed or expected to be claimed on a tax return should be recorded in the financial statements. Under ASC 740-10, the Company may recognize the tax benefit from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities, based on the technical merits of the position. The Company has determined that the Company has no significant uncertain tax positions requiring recognition under ASC 740-10 and therefore has not included a tabular rollforward of unrecognized tax benefits. As there are no uncertain tax positions recognized, interest and penalties have not been accrued. The Company is subject to income tax in the U.S., as well as various state and international jurisdictions. The Company has not been audited by any state tax authorities in connection with income taxes. The Company has not been audited by international tax authorities or any states in connection with income taxes. The Company’s New York State tax returns have been subject to annual desk reviews which have resulted in insignificant adjustments to the related franchise tax liabilities and credits. The Company is no longer subject to federal and state examination for tax years ending prior to December 31, 2016; tax years ending December 31, 2016 through December 31, 2019 remain open to examination. The Republic of Ireland is the Company’s only significant foreign jurisdiction. The Company is no longer subject to Ireland tax examination for tax years ending prior to December 31, 2015 (as Ireland has not initiated an audit of 2014 as of December 31, 2019); tax years ending December 31, 2014 through December 31, 2018 remain open to examination. However, the Company’s tax years December 31, 1998 through December 31, 2019 generally remain open to adjustment for all federal, state and foreign tax matters until its net operating loss and tax credit carryforwards are utilized or expire prior to utilization, and the applicable statutes of limitation have expired in the utilization year. The federal and state tax authorities can generally reduce a net operating loss (but not create taxable income) for a period outside the statute of limitations in order to determine the correct amount of net operating loss which may be allowed as a deduction against income for a period within the statute of limitations. Delcath recognizes interest accrued related to unrecognized tax benefits and penalties, if incurred, as a component of income tax expense.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	(1 5 ) Subsequent Events Since January 1, 2020, the Company has issued 2,915 shares pursuant to conversions of Series E and Series E-1 Convertible Preferred Stock. In May 2018, the Company received a Demand Letter from a vendor for an outstanding balance owed at that time of $2.1 million. At that time, the Company agreed with the vendor on a payment plan for the balance owed. Subsequent to December 31, 2019, the vendor issued a notice of default relating to the Demand Letter. As a result, the Company paid $0.9 million, representing the remaining balance owed. In February 2020, we issued 2,717 shares of restricted common stock in relation to certain advisory services received by us. In connection with the foregoing, we relied upon the exemption from registration provided by Section 4(a)(2) of the Securities Act of 1933, as amended, for transactions not involving a public offering. In connection with our proposed public offering (the “Proposed Offering”) of our securities pursuant to our registration statement on Form S-1 (File No. 333-235904), and the potential listing of the Company’s common stock, par value $0.01 per share (the “Common Stock”) on the Nasdaq Capital Market in connection therewith, on March 11, 2020, the Company entered into a support and conversion agreement (the “Support and Conversion Agreement”) with Rosalind Master Fund L.P. and Rosalind Opportunities Fund I L.P. (collectively, “Rosalind”) and our executive officers. The Support and Conversion Agreement provides that, among other things, the executive officers have agreed to receive payment of the net after-tax amount of their 2019 annual incentive bonuses aggregating $221,000 in unregistered shares of Common Stock, valued at the public offering price of the securities sold in the Proposed Offering, upon the consummation of the Proposed Offering. In addition, following the consummation of the Proposed Offering, (i) Rosalind has agreed that from time to time the Company may require them to convert all or a portion of their 8% senior secured promissory notes in the aggregate principal amount of $2 million (the “Notes”) into shares of the Company’s Series E convertible preferred stock (the “Series E Preferred Stock”) and Series E warrants at the contractual conversion price of $1,500 per share of Series E Preferred Stock in certain circumstances described below (a “Rosalind Conversion”), and (ii) the Company’s executive officers have agreed to receive payment of the net after-tax amounts of back pay and deferred bonuses aggregating $765,000 in unregistered shares of Common Stock (an “Equitization Transaction,” and together with a Rosalind Conversion, an “Equity Infusion”). The shares of Common Stock issuable in an Equitization Transaction would have a value equal to the greater of (x) the last reported sale price per share as of the trading day immediately preceding the Equity Infusion Date (as defined below) and (y) the volume-weighted average price of the Common Stock for the five trading days immediately preceding the Equity Infusion Date. The recent outbreak of a novel strain of coronavirus (COVID-19) has had an impact on our ability to monitor data at our clinical trial sites and is likely to cause a decline in product revenue for the forseeable future as many hospitals are prioritizing the treatment of patients diagnosed with COVID-19. This situation is rapidly changing 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.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Liquidity and Going Concern	Liquidity and Going Concern The accompanying 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. As shown in the accompanying consolidated financial statements during the year ended December 31, 2019, the Company incurred net operating losses of $8.9 million and used $23.7 million of cash for its operating activities. These factors among others raise substantial doubt about the Company’s ability to continue as a going concern for a reasonable period of time. 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 us 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 our 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 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. At December 31, 2019, management believed that its capital resources were adequate to fund operations through June 2020. Additional working capital will be required to continue operations.
Use of Estimates	Use of Estimates The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. The amounts of assets and liabilities reported in the Company’s consolidated balance sheets and the amount of revenues and expenses reported for each of the periods presented are affected by estimates and assumptions, which are used for, but not limited to, the accounting for derivative instrument liabilities, stock-based compensation, valuation of inventory, impairment of long-lived assets, income taxes and operating expense accruals. Such assumptions and estimates are subject to change in the future as additional information becomes available or as circumstances are modified. Actual results could differ from these estimates.
Cash Equivalents and Concentrations of Credit Risk	Cash Equivalents and Concentrations of Credit Risk The Company considers investments with original maturities of three months or less at date of acquisition to be cash equivalents. The Company has deposits that exceed amounts insured by the Federal Deposit Insurance Corporation (“FDIC”), however, the Company does not consider this a significant concentration of credit risk based on the strength of the financial institution.
Restricted Cash	Restricted Cash Cash and cash equivalents that are restricted as to withdrawal or use under the terms of certain contractual agreements are recorded as restricted cash on the accompanying consolidated balance sheets.
Accounts Receivable	Accounts Receivable Accounts receivable, principally trade, are generally due within 30 days and are stated at amounts due from customers. Collections and payments from customers are monitored and a provision for estimated credit losses may be created based upon historical experience and specific customer collection issues that may be identified.
Inventories	Inventories Inventories are valued at the lower of cost or net realizable value using the first-in, first-out method. The reported net value of inventory includes finished saleable products, work-in-process, and raw materials that will be sold or used in future periods. The Company reserves for expired, obsolete, and slow-moving inventory.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are recorded at cost, less accumulated depreciation. The Company provides for depreciation on a straight line basis over the estimated useful lives of the assets which range from three to seven years. Leasehold improvements will be amortized over the shorter of the lease term or the estimated useful life of the related assets when they are placed into service. The Company evaluates property, plant and equipment for impairment periodically to determine if changes in circumstances or the occurrence of events suggest the carrying value of the asset or asset group may not be recoverable.
Derivative Instrument Liability	Derivative Instrument Liability The Company accounts for derivative instruments in accordance with Accounting Standards Codification (“ASC”) 815, Derivatives and Hedging, which establishes accounting and reporting standards for derivative instruments and hedging activities, including certain derivative instruments embedded in other financial instruments or contracts and requires recognition of all derivatives on the balance sheet at fair value, regardless of the hedging relationship designation. Accounting for changes in the fair value of the derivative instruments depends on whether the derivatives qualify as hedge relationships and the types of relationships designated are based on the exposures hedged. At December 31, 2019 and 2018, the Company did not have any derivative instruments that were designated as hedges.
Fair Value Measurements	Fair Value Measurements The Company adheres to ASC 820, Fair Value Measurement, which defines fair value, establishes a framework for measuring fair value, and expands disclosures about fair value measurements. ASC 820 applies to reported balances that are required or permitted to be measured at fair value under existing accounting pronouncements; accordingly, the standard does not require any new fair value measurements of reported balances. ASC 820 emphasizes that fair value is a market-based measurement, not an entity-specific measurement. Therefore, a fair value measurement should be determined based on the assumptions that market participants would use in pricing the asset or liability. As a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a fair value hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity (observable inputs that are classified within Levels 1 and 2 of the hierarchy) and the reporting entity’s own assumptions about market participant assumptions (unobservable inputs classified within Level 3 of the hierarchy). • Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities that the Company has the ability to access. • Level 2 inputs are inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs may include quoted prices for similar assets and liabilities in active markets, as well as inputs that are observable for the asset or liability (other than quoted prices), such as interest rates, foreign exchange rates, and yield curves that are observable at commonly quoted intervals. • Level 3 inputs are unobservable inputs for the asset or liability, which is typically based on an entity’s own assumptions, as there is little, if any, related market activity. In instances where the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level input that is significant to the fair value measurement in its entirety. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment and considers factors specific to the asset or liability.
Revenue Recognition	Revenue Recognition Revenue is generated from proprietary and partnered product sales and license and royalty arrangements. Revenue is recognized when or as we transfer control of the promised goods or services to our customers in an amount that reflects the consideration to which we expect to be entitled to in exchange for those goods or services. When obligations or contingencies remain after the products are shipped, such as training and certifying the treatment centers, revenue is deferred until the obligations or contingencies are satisfied. We may enter into contracts with partners that contain multiple elements such as licensing, development, manufacturing and commercialization components. These arrangements are often complex and we may receive various types of consideration over the life of the arrangement, including: up-front fees, reimbursements for research and development services, milestone payments, payments on product shipments, margin sharing arrangements, license fees and royalties. Our results of operations for reporting periods beginning on or after January 1, 2018 are presented under ASC 606, Revenue from Contracts with Customers, while prior period amounts, as reported, are not adjusted. The effects of the adoption of the new standard in 2018 were not material to our consolidated financial statements. In assessing our revenue arrangements in accordance with ASC 606, Revenue from Contracts with Customers, we must identify the contract, determine the transaction price including an estimation of any variable consideration we expect to receive in connection with the contract, identify the promises of goods or services to the customer and each distinct performance obligation, allocate the transaction price to each of the performance obligations, and recognize revenue when or as the performance obligations are satisfied. Each of these steps in the revenue recognition process requires management to make judgements and/or estimates. The most significant judgements and estimates involve the determination of variable consideration to be included in the transaction price. Variable consideration is recognized at an amount we believe is not subject to significant reversal and is adjusted at each reporting period if the most likely amount of expected consideration changes or becomes fixed. We believe this provides a reasonable basis for recognizing revenue, however, actual results could differ from estimates and significant changes in estimates could impact our results of operations in future periods.
Deferred Revenue	Deferred Revenue License fees and milestones received in exchange for the grant of a license
Selling, General and Administrative	Selling, General and Administrative Selling, general and administrative costs include personnel costs and related expenses for the Company’s sales, marketing, general management and administrative staff, recruitment, costs related to the Company’s commercialization efforts in Europe, professional service fees, professional license fees, business development and certain general legal activities. All such costs are charged to expense when incurred.
Research and Development	Research and Development Research and development costs include the costs of materials used for clinical trials and R&D, personnel costs associated with device and pharmaceutical R&D, clinical affairs, medical affairs, medical science liaisons, and regulatory affairs, costs of outside services and applicable indirect costs incurred in the development of the Company’s proprietary drug delivery system. All such costs are charged to expense when incurred.
Stock Based Compensation	Stock Based Compensation The Company accounts for its share-based compensation in accordance with the provisions of ASC 718, Stock-Based Compensation, which establishes accounting for equity instruments exchanged for employee services and ASC 505-50, Equity-Based Payments to Non-Employees, which establishes accounting for equity-based payments to non-employees. Under the provisions of ASC 718, share-based compensation is measured at the grant date, based upon the fair value of the award, and is recognized as an expense over the option holders’ requisite service period (generally the vesting period of the equity grant). The Company is required to record compensation cost for all share-based payments granted to employees based upon the grant date fair value, estimated in accordance with the provisions of ASC 718. Under the provisions of ASC 505-50, measurement of compensation cost related to common shares issued to non-employees for services is based on the value of the services provided or the fair value of the shares issued. The measurement of non-employee stock-based compensation is subject to periodic adjustment as the underlying equity instrument vests. The Company expenses its share-based compensation for share-based payments granted under the accelerated method, which treats each vesting tranche as if it were an individual grant. The Company periodically grants stock options for a fixed number of shares of common stock to its employees, directors and non-employee contractors, with an exercise price greater than or equal to the fair market value of Delcath’s common stock at the date of the grant. The Company estimates the fair value of stock options using an option pricing model. Key inputs used to estimate the fair value of stock options include the exercise price of the award, the expected post-vesting option life, the expected volatility of Delcath’s stock over the option’s expected term, the risk-free interest rate over the option’s expected term, and Delcath’s expected annual dividend yield. Estimates of fair value are not intended to predict actual future events or the value ultimately realized by persons who receive equity awards.
Income Taxes	Income Taxes The Company accounts for income taxes following the asset and liability method in accordance with the ASC 740, Income Taxes. Under such method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the consolidated financial statement carrying amounts of existing assets and liabilities and their respective tax bases. The Company applies the accounting guidance issued to address the accounting for uncertain tax positions. This guidance clarifies the accounting for income taxes, by prescribing a minimum recognition threshold a tax position is required to meet before being recognized in the financial statements as well as provides guidance on derecognition, measurement, classification, interest and penalties, accounting in interim periods, disclosure and transition. The Company classifies interest and penalty expense related to uncertain tax positions as a component of income tax expense. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years that the asset is expected to be recovered or the liability settled. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized. The ultimate realization of deferred tax assets depends on the generation of future taxable income during the period in which related temporary differences become deductible. The Company considers the scheduled reversal of deferred tax liabilities, projected future taxable income and tax planning strategies in its assessment of a valuation allowance. See Note 14 for additional information.
Net Loss per Common Share	Net Loss per Common Share Basic net loss per share is determined by dividing net loss by the weighted average shares of common stock outstanding during the period, without consideration of potentially dilutive securities except for those shares that are issuable for little or no cash consideration. Diluted net loss per share is determined by dividing net loss by diluted weighted average shares outstanding. Diluted weighted average shares reflects the dilutive effect, if any, of potentially dilutive common shares, such as stock options and warrants calculated using the treasury stock method. In periods with reported net operating losses, all common stock options and warrants are generally deemed anti-dilutive such that basic net loss per share and diluted net loss per share are equal. However, in certain periods in which the exercise price of the warrants was less than the last reported sales price of Delcath’s common stock on the final trading day of the period and there is a gain recorded pursuant to the change in fair value of the warrant derivative liability, the impact of gains related to the mark-to-market adjustment of the warrants outstanding at the end of the period is reversed and the treasury stock method is used to determine diluted earnings per share. As discussed in Note 11, the Series E Preferred Stock and the Series E-1 Preferred Stock were each determined to have a beneficial conversion feature which was accounted for as a deemed dividend. For the years ended December 31, 2019 and 2018 the following potentially dilutive securities were excluded from the computation of diluted earnings per share because their effects would be antidilutive: 2019 2018 Common stock warrants - equity — 6,005 Common stock warrants - liability 1,826,608 271 Assumed conversion of Series E and Series E-1 Preferred Stock 1,802,008 — Assumed conversion of convertible notes 63,493 3,681 Stock options 1,640 — Total 3,693,749 9,957
Segment Information	Segment Information The Company currently operates in one business segment, which is the development and commercialization of Melphalan/HDS and CHEMOSAT. A single management team that reports to the CEO and President comprehensively manages the business. Accordingly, the Company does not have separately reportable segments.
Foreign Currency and Currency Translation	Foreign Currency and Currency Translation Transactions that are denominated in a foreign currency are remeasured into the functional currency at the current exchange rate on the date of the transaction. Any foreign currency-denominated monetary assets and liabilities are subsequently remeasured at current exchange rates, with gains or losses recognized as foreign exchange (losses)/gains in the statements of operations. The assets and liabilities of the Company’s international subsidiaries are translated from their functional currencies into United States dollars at exchange rates prevailing at the balance sheet date. The majority of the foreign subsidiaries revenues and operating expenses are denominated in Euros. The reporting currency for the Company is the United States Dollar (“USD”). Average rates of exchange during the period are used to translate the statement of operations, while historical rates of exchange are used to translate any equity transactions. Translation adjustments arising on consolidation due to differences between average rates and balance sheet rates, as well as unrealized foreign exchange gains or losses arising from translation of intercompany loans that are of a long-term-investment nature, are recorded in other comprehensive income.
Recently Adopted Accounting Pronouncements and Accounting Standards to be Adopted	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 Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842) Codification Improvements to Topic 842, Leases Leases (Topic 842)—Targeted Improvements Leases The Company has elected certain practical expedients permitted under the transition guidance within ASC 842 to leases that commenced before January 1, 2019, including the package of practical expedients. The election of the package of practical expedients resulted in the Company not reassessing prior conclusions under ASC 840 related to lease identification, lease classification and initial direct costs for expired and existing leases prior to January 1, 2019. The Company did not elect the practical expedient to not record short-term leases on its consolidated balance sheet. The adoption of ASU 2016-02 did not have a significant impact on the Company’s consolidated results of operations or cash flows. See Note 9 for additional information. SEC Disclosure Update and Simplification In August 2018, the SEC adopted the final rule under SEC Release No. 33-10532, Disclosure Update and Simplification, amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders' equity for interim financial statements. Under the amendments, an analysis of changes in each caption of stockholders' equity presented in the balance sheet must be provided in a note or separate statement. The analysis should present a reconciliation of the beginning balance to the ending balance of each period for which a statement of comprehensive income is required to be filed. This final rule was effective on November 5, 2018. The adoption did not have a material impact on the Company’s consolidated financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Anti-dilutive securities excluded from the computation of earnings per share	For the years ended December 31, 2019 and 2018 the following potentially dilutive securities were excluded from the computation of diluted earnings per share because their effects would be antidilutive: 2019 2018 Common stock warrants - equity — 6,005 Common stock warrants - liability 1,826,608 271 Assumed conversion of Series E and Series E-1 Preferred Stock 1,802,008 — Assumed conversion of convertible notes 63,493 3,681 Stock options 1,640 — Total 3,693,749 9,957

Restricted Cash (Tables)

Restricted Cash (Tables)	12 Months Ended
	Dec. 31, 2019
Restricted Cash [Abstract]
Schedule of Restricted Cash	(in thousands) December 31, 2019 December 31, 2018 Cash and cash equivalents $ 10,002 $ 2,516 Convertible Notes — — Letters of credit 131 1,012 Security for credit cards 50 50 Total cash, cash equivalents and restricted cash shown in the statement of cash flows $ 10,183 $ 3,578

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2019
Inventory Disclosure [Abstract]
Schedule of inventories	Inventories consist of: (in thousands) December 31, 2019 December 31, 2018 Raw materials $ 375 $ 358 Work-in-process 279 500 Finished goods — — Total Inventory $ 654 $ 858

Prepaid Expenses and Other Cu_2

Prepaid Expenses and Other Current Assets (Tables)	12 Months Ended
	Dec. 31, 2019
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets include the following: (in thousands) December 31, 2019 December 31, 2018 Clinical trial expenses 725 — Insurance premiums 589 140 Security deposit 51 51 Income tax and VAT receivable 31 579 Other 1 363 128 Total prepaid expenses and other current assets $ 1,759 $ 898 1

Property, Plant, and Equipment

Property, Plant, and Equipment (Tables)	12 Months Ended
	Dec. 31, 2019
Property Plant And Equipment [Abstract]
Components of property, plant and equipment	Property, plant, and equipment consists of: (in thousands) December 31, 2019 December 31, 2018 Estimated Useful Life Buildings and land $ 589 $ 589 30 years - Buildings Enterprise hardware and software 1,739 1,742 3 years Leaseholds 1,695 1,701 Lesser of lease term or estimated useful life Equipment 1,025 1,002 7 years Furniture 198 198 5 years Property, plant and equipment, gross 5,246 5,232 Accumulated depreciation (4,511 ) (4,307 ) Property, plant and equipment, net $ 735 $ 925

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2019
Payables And Accruals [Abstract]
Schedule of current accrued expenses	Current accrued expenses include the following: (in thousands) December 31, 2019 December 31, 2018 Clinical trial expenses $ 2,497 $ 4,530 Compensation, excluding taxes 3,525 1,785 Professional fees 263 190 Short-term portion of lease restructuring - 184 Other 1 662 1,275 Total accrued expenses $ 6,947 $ 7,964 1

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Summary of Operating and Financing Leases	The following table summarizes the Company’s operating and financing leases as of December 31, 2019: (in thousands) US Ireland Total Lease Cost Operating lease cost $ 710 $ 210 $ 920 Financing lease cost 42 — 42 Sublease income (215 ) (175 ) (390 ) Total $ 537 $ 35 $ 572 Other information Operating cash flows out from operating leases (755 ) (210 ) (965 ) Operating cash flows in from operating leases 215 175 390 Operating cash flows out from financing leases (39 ) — (39 ) Right-of-use assets exchanged for new operating lease liabilities 874 — 874 Weighted average remaining lease term 1.1 1.8 Weighted average discount rate - operating leases 8 % 8 %
Schedule of Maturity of Operating Leases Excluding Short-Term Leases	Maturities of the Company’s operating leases, excluding short-term leases, are as follows: (in thousands) US Ireland Total Year ended December 31, 2020 $ 498 $ 210 $ 708 Year ended December 31, 2021 79 122 201 Total 577 332 909 Less present value discount (27 ) (21 ) (48 ) Operating lease liabilities included in the condensed consolidated balance sheet at December 31, 2019 $ 550 $ 311 $ 861

Outstanding Debt (Tables)

Outstanding Debt (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Summary of the Notes by Maturity Dates	The following table provide a summary of the outstanding Note at December 31, 2019 : (in millions) Conversion price Current interest rate Principal Long term convertible notes payable 8.0% July 2019 Notes $ 1,500 8 % $ 2.0 The following table provides a summary of the Notes by their maturity dates (absent provisions of default) at December 31, 2018: (in millions) Interest rate Conversion price Principal Unamortized Discount Carrying value December 4, 2018 8.0% $ 1.75 $ 1.7 $ — $ 1.7 March 1, 2019 8.0% 1.75 0.6 (0.5 ) 0.1 March 21, 2019 8.0% 1.75 0.4 (0.2 ) 0.2 December 4, 2019 8.0% 1.75 0.9 (0.9 ) — March 1, 2020 8.0% 1.75 0.8 (0.8 ) — March 21, 2020 8.0% 1.75 0.1 (0.1 ) — Total Convertible Notes Payable, net $ 4.5 $ (2.5 ) $ 2.0

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2019
Stockholders Equity Note [Abstract]
Summary of Stock Option Activity	The following is a summary of stock option activity under the Plan for the year ended December 31, 2019: Number of Shares Weighted Average Exercise Price Weighted Remaining Contractual Term (Years) Aggregate Intrinsic Value Outstanding at January 1, 2019 — Granted 1,782 $ 196.70 Exercised — Cancelled/Forfeited (142 ) $ 196.70 Outstanding at December 31, 2019 1,640 $ 196.70 9.1 $ — Exercisable at December 31, 2019 1,502 $ 196.70 9.1 $ —
Summary of Recognized Share-based Compensation Cost	(in thousands) Twelve months ended December 31, 2019 Twelve months ended December 31, 2018 Selling, general and administrative $ 213,807 $ 120,850 Research and development 59,391 (61,867 ) Total $ 273,198 $ 58,983
Summary of Warrant Activity	The following is a summary of warrant activity for the years ended December 31, 2019 and 2018: Warrants Exercise Share Weighted Exercise Price Weighted Average Remaining (Years) Outstanding at January 1, 2018 20 $857,500 - $13,798,400,000 $ 4,868,205,366 4.88 Warrants issued 100,352 222 Warrants exercised (6,536 ) 1,252 Warrants expired (1 ) 13,798,400,000 Outstanding at December 31, 2018 93,835 $7 - $7,000 $ 151 5.75 Warrants issued 1,826,579 42 Warrants exercised (11,285 ) 7 Warrants exchanged (82,521 ) 170 Outstanding at December 31, 2019 1,826,608 $7 - $23 $ 23 4.99

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair value measurements using significant unobservable inputs	The table below presents the activity within Level 3 of the fair value hierarchy for the twelve months ended December 31, 2019: Fair Value Measurements Using Significant Unobservable Inputs (Level 3) (in thousands) Warrant Liability Balance at January 1, 2018 $ 560 Fair value of warrants issued 23,533 Total change in the liability included in earnings (19,706 ) Reclass from liability to equity (4,210 ) Fair value of warrants exchanged (144 ) Balance at December 31, 2018 33 Total change in the liability included in earnings (17,498 ) Reclass from liability to equity (11 ) Fair value of warrants issued 20,844 Balance at December 31, 2019 3,368
Schedule of fair value of the outstanding warrants	The fair value of the Warrants at December 31, 2019 was determined by using option pricing models assuming the following: December 31, December 31, 2019 2018 Expected life (in years) 4.6 1.1 - 5.1 Expected volatility 207.5% 145.7% - 265.3% Risk-free interest rates 1.7% 2.5% - 2.6%
Assets and liabilities measured at fair value on a recurring basis	The table below presents the Company’s assets and liabilities measured at fair value on a recurring basis as of December 31, 2019 and 2018, aggregated by the level in the fair value hierarchy within which those measurements fall. Assets and Liabilities Measured at Fair Value on a Recurring Basis Assets and Liabilities Measured at Fair Value on a Recurring Basis Level 1 Level 2 Level 3 Balance at December 31, (in thousands) 2019 2018 2019 2018 2019 2018 2019 2018 Liabilities Derivative instrument liabilities $ — $ — $ — $ — $ 3,368 $ 33 $ 3,368 $ 33

Commitments (Tables)

Commitments (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Schedule of future minimum lease payments, net of receipts due under terms of subleases under all operating leases	Future minimum lease payments, net of receipts due under the terms of subleases, under all operating leases at December 31, 2019 are as follows: (in thousands) Future Lease Payments 2020 635 2021 79 $ 714

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of Loss Before Income Taxes	Loss before taxes consists of: (in thousands) December 31, 2019 December 31, 2018 Domestic $ (4,882 ) $ (12,961 ) Foreign (3,997 ) (6,261 ) Income (loss) before taxes $ (8,879 ) $ (19,222 )
Income tax reconciliation	The provision for income taxes differs from the amount computed by applying the statutory rate as follows: (in thousands) December 31, 2019 December 31, 2018 Income taxes using U.S federal statutory rate $ (1,865 ) $ (4,037 ) Tax Cuts and Jobs Act — — Nondeductible interest 994 2,273 Loss on extinguishment of debt 361 236 Loss of tax benefit of federal net operating loss carryforwards — (588 ) Loss of tax benefit of state net operating loss carryforwards 1,477 1,040 Loss of tax benefit of federal tax credit carryforwards 324 495 Amortization of gain on IP migration — — State income taxes, net of federal benefit (1,461 ) (2,355 ) Foreign rate differential 664 1,166 Valuation allowance 3,512 6,323 Derivative charge (3,674 ) (4,138 ) Stock option exercises and cancellations — 215 Research and development costs (316 ) (636 ) Other (16 ) 6 $ — $ —
Significant components of deferred tax assets	Significant components of the Company’s deferred tax assets are as follows: (in thousands) December 31, 2019 December 31, 2018 Deferred tax assets: Equity compensation $ 84 $ — Accrued liabilities — 519 Research tax credits 135 161 Lease obligation 206 Other 72 60 Net operating losses 14,502 10,624 Total deferred tax assets $ 14,999 $ 11,364 Deferred tax liabilities: Beneficial conversion feature — — Right of use asset 206 — Other — — Total deferred tax liabilities 206 — Valuation allowance 14,793 11,364 Net deferred tax assets $ — $ —
Summary of Change in Valuation	The change in valuation is as follows: (in thousands) December 31, 2019 December 31, 2018 Beginning balance $ 11,364 $ 5,972 Charged to costs and expenses 3,512 6,323 Charged to additional paid-in capital — — Charged to retained earnings — (834 ) Charged to other comprehensive income (83 ) (97 ) Ending balance $ 14,793 $ 11,364

Description of Business - Addit

Description of Business - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Net loss	$ 8,879	$ 19,222
Net cash used in operating activities	$ 23,690	$ 14,732

Basis of Consolidated Financi_2

Basis of Consolidated Financial Statement Presentation - Additional Information (Details)	Dec. 24, 2019	May 02, 2018
Basis Of Condensed Consolidated Financial Statement Presentation [Abstract]
Reverse stock split ratio	0.00142	0.002
Reverse stock split	1:700	1:500

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2019DerivativeSegment	Dec. 31, 2018Derivative
Summary Of Significant Accounting Policies [Line Items]
Maximum period of investments with original maturities from date of acquisition to be cash equivalents	3 months
Number of business segments | Segment	1
Designated as Hedges [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of derivative instruments | Derivative	0	0
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, estimated useful life	3 years
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, estimated useful life	7 years

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Shares Excluded from the Computation of Diluted Earnings per Share (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	3,693,749	9,957
Common Stock Warrants - Equity [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)		6,005
Common Stock Warrants - Liability [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	1,826,608	271
Assumed Conversion of Series E and Series E-1 Preferred Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	1,802,008
Assumed Conversion of Convertible Notes [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	63,493	3,681
Stock Options [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	1,640

Restricted Cash - Schedule of R

Restricted Cash - Schedule of Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restricted Cash [Abstract]
Cash and cash equivalents	$ 10,002	$ 2,516
Letters of credit	131	1,012
Security for credit cards	50	50
Total cash, cash equivalents and restricted cash shown in the statement of cash flows	$ 10,183	$ 3,578	$ 5,324

Inventories - Schedule of Inven

Inventories - Schedule of Inventories (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Raw materials	$ 375	$ 358
Work-in-process	279	500
Total Inventory	$ 654	$ 858

Prepaid Expenses and Other Cu_3

Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Prepaid Expense And Other Assets Current [Abstract]
Clinical trial expenses	$ 725
Insurance premiums	589	$ 140
Security deposit	51	51
Income tax and VAT receivable	31	579
Other	363	128
Total prepaid expenses and other current assets	$ 1,759	$ 898

Prepaid Expenses and Other Cu_4

Prepaid Expenses and Other Current Assets - Additional Information (Details)	Dec. 31, 2019	Dec. 31, 2018
Prepaid Expense And Other Assets Current [Abstract]
Maximum percentage of prepaid expenses and other current assets (in hundredths)	5.00%	5.00%

Property, Plant, and Equipmen_2

Property, Plant, and Equipment - Components of Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 5,246	$ 5,232
Accumulated depreciation	(4,511)	(4,307)
Property, plant and equipment, net	735	925
Buildings and Land [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	589	589
Enterprise Hardware and Software [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 1,739	1,742
Property, plant and equipment, estimated useful life	3 years
Leaseholds [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 1,695	1,701
Property, plant and equipment, estimated useful life	Lesser of lease term or estimated useful life
Equipment [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 1,025	1,002
Property, plant and equipment, estimated useful life	7 years
Furniture [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 198	$ 198
Property, plant and equipment, estimated useful life	5 years
Buildings [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, estimated useful life	30 years

Property, Plant, and Equipmen_3

Property, Plant, and Equipment - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Depreciation expense	$ 212	$ 444

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Current Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Payables And Accruals [Abstract]
Clinical trial expenses	$ 2,497	$ 4,530
Compensation, excluding taxes	3,525	1,785
Professional fees	263	190
Short-term portion of lease restructuring		184
Other	662	1,275
Total accrued expenses	$ 6,947	$ 7,964

Accrued Expenses - Schedule o_2

Accrued Expenses - Schedule of Current Accrued Expenses (Parenthetical) (Details)	Dec. 31, 2019	Dec. 21, 2018
Payables And Accruals [Abstract]
Maximum percentage of current liabilities accrued (in hundredths)	5.00%	5.00%

Leases - Additional Information

Leases - Additional Information (Details)	Dec. 31, 2019
Leases [Abstract]
Lease term	12 months

Leases - Summary of Operating a

Leases - Summary of Operating and Financing Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Lease Cost
Operating lease cost	$ 920
Financing lease cost	42
Sublease income	(390)
Total	572
Other information
Operating cash flows out from operating leases	(965)
Operating cash flows in from operating leases	390
Operating cash flows out from financing leases	(39)
Right-of-use assets exchanged for new operating lease liabilities	874	$ 0
U.S. [Member]
Lease Cost
Operating lease cost	710
Financing lease cost	42
Sublease income	(215)
Total	537
Other information
Operating cash flows out from operating leases	(755)
Operating cash flows in from operating leases	215
Operating cash flows out from financing leases	(39)
Right-of-use assets exchanged for new operating lease liabilities	$ 874
Weighted average remaining lease term	1 year 1 month 6 days
Weighted average discount rate - operating leases	8.00%
Ireland [Member]
Lease Cost
Operating lease cost	$ 210
Sublease income	(175)
Total	35
Other information
Operating cash flows out from operating leases	(210)
Operating cash flows in from operating leases	$ 175
Weighted average remaining lease term	1 year 9 months 18 days
Weighted average discount rate - operating leases	8.00%

Leases - Schedule of Maturity o

Leases - Schedule of Maturity of Operating Leases Excluding Short-Term Leases (Details) $ in Thousands	Dec. 31, 2019USD ($)
Lessee Lease Description [Line Items]
Year ended December 31, 2020	$ 708
Year ended December 31, 2021	201
Total	909
Less present value discount	(48)
Operating lease liabilities included in the condensed consolidated balance sheet at December 31, 2019	861
U.S. [Member]
Lessee Lease Description [Line Items]
Year ended December 31, 2020	498
Year ended December 31, 2021	79
Total	577
Less present value discount	(27)
Operating lease liabilities included in the condensed consolidated balance sheet at December 31, 2019	550
Ireland [Member]
Lessee Lease Description [Line Items]
Year ended December 31, 2020	210
Year ended December 31, 2021	122
Total	332
Less present value discount	(21)
Operating lease liabilities included in the condensed consolidated balance sheet at December 31, 2019	$ 311

Outstanding Debt - Additional I

Outstanding Debt - Additional Information (Details) - USD ($)	Mar. 29, 2019	May 23, 2019	Dec. 31, 2019	Jun. 06, 2019	Apr. 30, 2019	Dec. 31, 2018	Sep. 21, 2018
Debt Instrument [Line Items]
Debt instrument, principal face amount						$ 4,500,000
Series D Preferred Shares [Member]
Debt Instrument [Line Items]
Interest rate	8.00%
Preferred stock, stated value	$ 1,160,000
Proceeds from exchange of senior secured promissory note	400,000
Issuance of senior secured promissory note in exchange of preferred stock	$ 1,560,000
Maturity date	Apr. 1, 2020
Senior Secured Promissory Notes [Member]
Debt Instrument [Line Items]
Debt instrument, principal face amount				$ 2,000,000
Interest rate				8.00%
Senior Secured Notes
Debt Instrument [Line Items]
Debt instrument, principal face amount		$ 3,300,000
Interest rate		8.00%
Maturity period		6 months
Senior Secured Convertible Notes
Debt Instrument [Line Items]
Debt instrument, principal face amount							$ 9,400,000
Interest rate							8.00%
Debt instrument maturity start date			Dec. 31, 2018
Debt instrument maturity end date			Mar. 31, 2021
8.0% 2018 Notes [Member] | Short Term Notes Payable [Member]
Debt Instrument [Line Items]
Debt instrument, notice of default description			Company received notices of default from the investors in the 2018 Notes which resulted in a 25%, or $1.1 million, increase in principal and an increase in the interest rates from 8% to 18%.
Debt instrument, default amount percentage					25.00%
Debt instrument, default amount					$ 1,100,000
Increase in interest rate on notes in event of default					18.00%
Series D Warrants [Member]
Debt Instrument [Line Items]
Number of common shares issuable on cancellation of warrants				5,605
Pre-Funded Series D Warrants [Member]
Debt Instrument [Line Items]
Number of common shares issuable on cancellation of warrants				100,000

Outstanding Debt - Summary of V

Outstanding Debt - Summary of Various Notes Issued (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2019
Debt Instrument [Line Items]
Principal	$ 4.5
Unamortized Discount	(2.5)
Carrying value	$ 2
December 4, 2018 [Member]
Debt Instrument [Line Items]
Maturity date	Dec. 4, 2018
Interest rate	8.00%
Conversion price	$ 1.75
Principal	$ 1.7
Carrying value	$ 1.7
March 1, 2019 [Member]
Debt Instrument [Line Items]
Maturity date	Mar. 1, 2019
Interest rate	8.00%
Conversion price	$ 1.75
Principal	$ 0.6
Unamortized Discount	(0.5)
Carrying value	$ 0.1
March 21, 2019 [Member]
Debt Instrument [Line Items]
Maturity date	Mar. 21, 2019
Interest rate	8.00%
Conversion price	$ 1.75
Principal	$ 0.4
Unamortized Discount	(0.2)
Carrying value	$ 0.2
December 4, 2019 [Member]
Debt Instrument [Line Items]
Maturity date	Dec. 4, 2019
Interest rate	8.00%
Conversion price	$ 1.75
Principal	$ 0.9
Unamortized Discount	$ (0.9)
March 1, 2020 [Member]
Debt Instrument [Line Items]
Maturity date	Mar. 1, 2020
Interest rate	8.00%
Conversion price	$ 1.75
Principal	$ 0.8
Unamortized Discount	$ (0.8)
March 21, 2020 [Member]
Debt Instrument [Line Items]
Maturity date	Mar. 21, 2020
Interest rate	8.00%
Conversion price	$ 1.75
Principal	$ 0.1
Unamortized Discount	$ (0.1)
Long Term Convertible Notes Payable [Member] | 8.0% July 2019 Notes [Member]
Debt Instrument [Line Items]
Interest rate		8.00%
Conversion price		$ 1,500
Principal		$ 2

Stockholders' Equity - Preferre

Stockholders' Equity - Preferred Stock Issuances - Additional Information (Details) - USD ($)	Nov. 07, 2019	Jul. 11, 2019	Mar. 29, 2019	Sep. 30, 2018	Feb. 28, 2018	Dec. 31, 2019	Dec. 31, 2018	Aug. 19, 2019	Nov. 05, 2018
Stockholders Equity Note [Line Items]
Preferred stock, par value (in dollars per share)						$ 0.01	$ 0.01
Sale of common stock, net of expenses (in shares)				6,669	606
Fair value of warrants issued						$ 20,844,000	$ 28,539,000
Preferred stock, aggregate stated value						0	$ 0
Common Stock [Member]
Stockholders Equity Note [Line Items]
Conversion of stock, shares issued	813,473
Sale of common stock, net of expenses (in shares)							7,624
2019 Warrants [Member]
Stockholders Equity Note [Line Items]
Number of shares called upon exercise of warrant	824,587
Fair value of warrants issued						20,800,000
Series E Convertible Preferred Stock [Member] | July 2019 Private Placement [Member] | Securities Purchase Agreement [Member]
Stockholders Equity Note [Line Items]
Number of shares issued		20,000
Preferred stock, par value (in dollars per share)		$ 0.01
Shares issued, price per share		$ 1,000
Series E Preferred Stock and Related Warrants [Member]
Stockholders Equity Note [Line Items]
Debt and warrants exchanged for preferred stock						$ 11,800,000
Number of preferred stock and warrants issued upon conversion						11,500
Value of accounts payable exchanged						$ 100,000
Number of shares issued upon exchange of accounts payable						149
Number of shares issued upon exchange of investor waiver rights						923
Series E Preferred Stock and Related Warrants [Member] | July 2019 Private Placement [Member]
Stockholders Equity Note [Line Items]
Debt and warrants exchanged for preferred stock		$ 11,800,000
Number of preferred stock and warrants issued upon conversion		11,500
Value of accounts payable exchanged		$ 100,000
Number of shares issued upon exchange of accounts payable		149
Number of shares issued upon exchange of investor waiver rights		923
Series E-1 Convertible Preferred Stock [Member] | August 2019 Private Placement [Member] | Securities Purchase Agreement [Member]
Stockholders Equity Note [Line Items]
Number of shares issued								9,510
Preferred stock, par value (in dollars per share)								$ 0.01
Shares issued, price per share								$ 1,000
Preferred Stock [Member]
Stockholders Equity Note [Line Items]
Conversion price	$ 23.04					$ 42
Warrant exercise price	23.04					$ 42
Warrant exercisable term						5 years
Net proceeds from issuance of preferred stock						$ 26,600,000
Beneficial conversion feature						$ 18,300,000
Preferred Stock and 2019 Warrants [Member]
Stockholders Equity Note [Line Items]
Conversion of stock, description						The Conversion Price of the Preferred Stock and the Exercise Price of the 2019 Warrants were initially subject to adjustment in each of the following circumstances: (i) on the third trading day following the date that the Company effects a reverse stock split, or the Reverse Split Reset Date, (ii) the date that the initial registration statement covering the shares of common stock issuable upon the conversion of the Preferred Stock and the exercise of the 2019 Warrants is declared effective by the SEC, or the Registration Reset Date, and (iii) in the event that all of the shares of common stock which we were required to register with the SEC were not then registered on an effective registration statement, the date that all of the shares underlying the respective Preferred Stock and 2019 Warrants may be sold pursuant to Rule 144, or the Rule 144 Reset Date, each of such reset dates, a Reset Date and, collectively, the Reset Dates. On each Reset Date, the Conversion Price and the Exercise Price were to be reduced, and only reduced, to equal the lesser of (x) the then effective Conversion Price or Exercise Price, as applicable, and (y) 90% of the average of the five daily volume weighted average prices of the common stock immediately prior to each Reset Date, or the Reset Formula.
Private Placements and Debt Exchange [Member]
Stockholders Equity Note [Line Items]
Conversion price and exercise price per share	$ 16.10
Private Placements and Debt Exchange [Member] | Common Stock [Member]
Stockholders Equity Note [Line Items]
Sale of common stock, net of expenses (in shares)	3,429,680
Second Registration Statement [Member] | Common Stock [Member]
Stockholders Equity Note [Line Items]
Sale of common stock, net of expenses (in shares)	1,564,085
Series D Preferred Shares [Member]
Stockholders Equity Note [Line Items]
Preferred stock, par value (in dollars per share)									$ 0.01
Preferred stock, aggregate stated value			$ 1,160,000,000
Proceeds from exchange of senior secured promissory note			$ 400,000

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock Issuances - Additional Information (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Stockholders Equity Note [Line Items]
Common stock, shares issued (in shares)	67,091	14,715
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common Stock [Member]
Stockholders Equity Note [Line Items]
Convertible preferred stock, shares upon Conversion	13,455
Common stock, par value (in dollars per share)	$ 0.01
Series E and E1 Convertible Preferred Stock [Member]
Stockholders Equity Note [Line Items]
Common stock, shares issued (in shares)	565

Stockholders' Equity - Pre-Fund

Stockholders' Equity - Pre-Funded Series D Warrant Exercises - Additional Information (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Stockholders Equity Note [Line Items]
Warrants exercised	11,285	6,536
Pre-Funded Series D Warrants [Member]
Stockholders Equity Note [Line Items]
Warrants exercised		5,379

Stockholders' Equity - December

Stockholders' Equity - December 2018 Warrant Exchange - Additional Information (Details)	1 Months Ended
	Dec. 31, 2018shares
Exchange Agreement [Member]
Stockholders Equity Note [Line Items]
Shares of common stock issued to investors	1,179

Stockholders' Equity - Septembe

Stockholders' Equity - September 2018 Rights Offering - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Sep. 30, 2018	Feb. 28, 2018	Dec. 31, 2019	Dec. 31, 2018
Stockholders Equity Note [Abstract]
Sale of common stock, net of expenses (in shares)	6,669	606
Net proceeds from issuance of common stock	$ 7,000		$ 0	$ 10,917

Stockholders' Equity - February

Stockholders' Equity - February 2018 Financing - Additional Information (Details) $ / shares in Units, $ in Millions	1 Months Ended
	Sep. 30, 2018shares	Feb. 28, 2018USD ($)$ / sharesshares	Dec. 31, 2019$ / sharesshares	Dec. 31, 2018$ / sharesshares	Dec. 21, 2018USD ($)	Dec. 31, 2017$ / sharesshares
Stockholders Equity Note [Line Items]
Sale of common stock, net of expenses (in shares)	6,669	606
Number of pre-funded warrants		109
Net proceeds from issuance of private placement | $		$ 4.3
Number of warrants outstanding (in shares)			1,826,608	93,835		20
Maximum [Member]
Stockholders Equity Note [Line Items]
Warrants exercisable per share price (in dollars per share) | $ / shares			$ 23	$ 7,000		$ 13,798,400,000
Minimum [Member]
Stockholders Equity Note [Line Items]
Warrants exercisable per share price (in dollars per share) | $ / shares			$ 7	$ 7		$ 857,500
Contractual Term [Member]
Stockholders Equity Note [Line Items]
Warrants expiration period			4 years 7 months 6 days
Contractual Term [Member] | Maximum [Member]
Stockholders Equity Note [Line Items]
Warrants expiration period				5 years 1 month 6 days
Contractual Term [Member] | Minimum [Member]
Stockholders Equity Note [Line Items]
Warrants expiration period				1 year 1 month 6 days
Volatility [Member]
Stockholders Equity Note [Line Items]
Warrants measurement input			2.075
Volatility [Member] | Maximum [Member]
Stockholders Equity Note [Line Items]
Warrants measurement input				2.653
Volatility [Member] | Minimum [Member]
Stockholders Equity Note [Line Items]
Warrants measurement input				1.457
Risk Free Rate [Member]
Stockholders Equity Note [Line Items]
Warrants measurement input			0.017
Risk Free Rate [Member] | Maximum [Member]
Stockholders Equity Note [Line Items]
Warrants measurement input				0.026
Risk Free Rate [Member] | Minimum [Member]
Stockholders Equity Note [Line Items]
Warrants measurement input				0.025
February 2018 Warrants [Member]
Stockholders Equity Note [Line Items]
Warrants issued to purchase Common Stock		1,429,000,000
Value of warrants issued | $		$ 18.3
Warrants exercisable per share price (in dollars per share) | $ / shares		$ 7,000
Number of warrants outstanding (in shares)		273
February 2018 Warrants [Member] | Exercise Price [Member]
Stockholders Equity Note [Line Items]
Warrants measurement input | $ / shares		7,000
February 2018 Warrants [Member] | Contractual Term [Member]
Stockholders Equity Note [Line Items]
Warrants expiration period		6 years
February 2018 Warrants [Member] | Volatility [Member]
Stockholders Equity Note [Line Items]
Warrants measurement input		1.2268
February 2018 Warrants [Member] | Risk Free Rate [Member]
Stockholders Equity Note [Line Items]
Warrants measurement input		0.01
Pre-Funded Series D Warrants [Member] | Maximum [Member]
Stockholders Equity Note [Line Items]
Maximum offering and selling of stock and securities that entity make to raise capital | $					$ 100

Stockholders' Equity - Stock In

Stockholders' Equity - Stock Incentive Plans - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense related to non-vested share-based compensation awards	$ 25,000
Cost expected to be recognized over weighted average period	1 month 6 days
Share-based compensation (Income) expense	$ 273,198,000	$ 58,983,000
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation (Income) expense	300,000	(40,000)
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock compensation expense	$ 0	$ 100,000
2019 Equity Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for grant	502
2019 Equity Incentive Plan [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares reserved for issuance	2,142
2019 Equity Incentive Plan [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options, exercise price of common stock granted as percentage of fair value on the date of grant	100.00%

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Stock Option Activity (Details)	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Stockholders Equity Note [Abstract]
Number of Shares, Granted | shares	1,782
Number of Shares, Cancelled/Forfeited | shares	(142)
Number of Shares, Outstanding | shares	1,640
Number of Shares, Exercisable | shares	1,502
Weighted Average Exercise Price, Granted | $ / shares	$ 196.70
Weighted Average Exercise Price, Cancelled/Forfeited | $ / shares	196.70
Weighted Average Exercise Price, Outstanding | $ / shares	196.70
Weighted Average Exercise Price, Exercisable | $ / shares	$ 196.70
Weighted Average Remaining Contractual Term (Years), Outstanding	9 years 1 month 6 days
Weighted Average Remaining Contractual Term (Years), Exercisable	9 years 1 month 6 days

Stockholders' Equity - Summar_2

Stockholders' Equity - Summary of Recognized Share-based Compensation Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation (Income) expense	$ 273,198	$ 58,983
Selling, General and Administrative [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation (Income) expense	213,807	120,850
Research and Development [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation (Income) expense	$ 59,391	$ (61,867)

Stockholders' Equity - Summar_3

Stockholders' Equity - Summary of Warrant Activity (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Warrants outstanding [Roll Forward]
Outstanding, beginning of period (in shares)	93,835	20
Warrants issued (in shares)	1,826,579	100,352
Warrants exercised (in shares)	(11,285)	(6,536)
Warrants expired (in shares)		(1)
Warrants exchanged (in shares)	(82,521)
Outstanding, end of period (in shares)	1,826,608	93,835	20
Warrants, Weighted Average Exercise Price [Roll Forward]
Outstanding, beginning of period (in dollars per share)	$ 151	$ 4,868,205,366
Warrants issued (in dollars per share)	42	222
Warrants exercised (in dollars per share)	7	1,252
Warrants expired (in dollars per share)		13,798,400,000
Warrants exchanged (in dollars per share)	170
Outstanding, end of period (in dollars per share)	$ 23	$ 151	$ 4,868,205,366
Weighted average remaining life	4 years 11 months 26 days	5 years 9 months	4 years 10 months 17 days
Minimum [Member]
Warrants, Exercise Price per Share [Roll Forward]
Outstanding, (in dollars per share)	$ 7	$ 7	$ 857,500
Maximum [Member]
Warrants, Exercise Price per Share [Roll Forward]
Outstanding, (in dollars per share)	$ 23	$ 7,000	$ 13,798,400,000

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value Measurements Using Significant Unobservable Inputs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value Measurements Using Significant Unobservable Inputs (Level 3) [Roll Forward]
Beginning balance	$ 33	$ 560
Fair value of warrants issued	20,844	23,533
Total change in the liability included in earnings	(17,498)	(19,706)
Reclass from liability to equity	(11)	(4,210)
Fair value of warrants exchanged		(144)
Ending balance	$ 3,368	$ 33

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - shares	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Class Of Warrant Or Right [Line Items]
Number of warrants outstanding (in shares)	1,826,608	93,835	20
Febuary 2018 Warrants [Member]
Class Of Warrant Or Right [Line Items]
Number of warrants outstanding (in shares)		179

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value of Outstanding Warrants (Details)	Dec. 31, 2019	Dec. 31, 2018
Contractual Term [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants expiration period	4 years 7 months 6 days
Contractual Term [Member] | Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants expiration period		1 year 1 month 6 days
Contractual Term [Member] | Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants expiration period		5 years 1 month 6 days
Expected Volatility [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants measurement input	2.075
Expected Volatility [Member] | Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants measurement input		1.457
Expected Volatility [Member] | Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants measurement input		2.653
Risk-free Interest Rates [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants measurement input	0.017
Risk-free Interest Rates [Member] | Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants measurement input		0.025
Risk-free Interest Rates [Member] | Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Warrants measurement input		0.026

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - Derivative Instruments Liabilities [Member] - Recurring [Member] - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Liabilities [Abstract]
Total Liabilities	$ 3,368	$ 33
Level 3 [Member]
Liabilities [Abstract]
Total Liabilities	$ 3,368	$ 33

Commitments - Additional Inform

Commitments - Additional Information (Details)	1 Months Ended	12 Months Ended
	Jan. 31, 2019USD ($)ft²	Dec. 31, 2019USD ($)ft²	Dec. 31, 2018USD ($)	Sep. 30, 2018ft²
Operating Leased Assets [Line Items]
Rent expense, net of receipts under the terms of subleases		$ 500,000	$ 600,000
Park Road Lease Agreement [Member]
Operating Leased Assets [Line Items]
Square footage of office space (in square feet) | ft²	6,000
Annual base rent	$ 50,000
Operating lease term		2 years
Lease expiration date		Nov. 30, 2020
Office Space At 1633 Broadway, New York, NY [Member]
Operating Leased Assets [Line Items]
Square footage of office space (in square feet) | ft²				6,877
Annual base rent		$ 500,000
Letter of credit [Abstract]
Minimum letter of credit amount required to be maintained under lease agreement			$ 100,000
Expiration date of letter of credit		Feb. 28, 2021
Delcath's European Headquarters Lease Agreement [Member]
Operating Leased Assets [Line Items]
Square footage of office space (in square feet) | ft²		19,200
Annual base rent		$ 200,000
Operating lease term		10 years

Commitments - Schedule Future M

Commitments - Schedule Future Minimum Lease Payments, Net of Receipts Due Under Terms of Subleases Under All Operating Leases (Details) $ in Thousands	Dec. 31, 2019USD ($)
Future minimum lease payments under all operating leases [Abstract]
2020	$ 635
2021	79
Total future minimum payments due	$ 714

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Income tax expense	$ 0	$ 0
Percentage of valuation allowance against deferred tax assets	100.00%
Decrease in deferred tax assets valuation allowance	$ 3,400,000	5,400,000
U.S. corporate income tax rate	21.00%		34.00%
Provisional income tax due to reduction in deferred tax assets			$ 143,500
New York State [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards net, expected to expire unutilized and unavailable to offset future federal taxable income	$ 169,400,000
New York City [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards net, expected to expire unutilized and unavailable to offset future federal taxable income	$ 153,700,000
Earliest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Open tax period	Dec. 31, 1998
Latest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Open tax period	Dec. 31, 2019
Federal [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 246,300,000	230,000,000
Operating loss carryforwards, annual limitation	27,500
Operating loss carryforwards net, expected to expire unutilized and unavailable to offset future federal taxable income	207,000,000
Operating loss carryforwards available for offset future taxable income	39,300,000
Operating loss carryforwards for unlimited period	37,600,000
Federal [Member] | Expire Between 2019 and 2037 [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards available for offset future taxable income	$ 1,700,000
Federal [Member] | Earliest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, expiration dates	2020
Federal [Member] | Latest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, expiration dates	2037
Federal [Member] | Research and Development Tax Credit Carryforwards [Member]
Operating Loss Carryforwards [Line Items]
Tax credit carryforwards	$ 5,300,000	5,000,000
Tax credit carryforwards, expiration dates	2039
Tax credit carryforwards expected to expire unutilized	$ 100,000
State and City [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 11,200,000	11,200,000
Operating loss carryforwards, expiration dates	2039
Foreign [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 26,100,000	25,200,000
Federal and State [Member] | Earliest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Open tax period	Dec. 31, 2016
Federal and State [Member] | Latest Tax Year [Member]
Operating Loss Carryforwards [Line Items]
Open tax period	Dec. 31, 2019
Minimum [Member] | State and City [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 27,300,000	27,300,000
Maximum [Member]
Operating Loss Carryforwards [Line Items]
U.S. corporate income tax rate			35.00%
Maximum [Member] | State and City [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards	$ 180,600,000	$ 167,300,000

Income Taxes - Schedule of Loss

Income Taxes - Schedule of Loss Before Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments [Abstract]
Domestic	$ (4,882)	$ (12,961)
Foreign	(3,997)	(6,261)
Income (loss) before taxes	$ (8,879)	$ (19,222)

Income Taxes - Income tax recon

Income Taxes - Income tax reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Provision for income taxes [Abstract]
Income taxes using U.S federal statutory rate	$ (1,865)	$ (4,037)
Nondeductible interest	994	2,273
Loss on extinguishment of debt	361	236
Loss of tax benefit of federal net operating loss carryforwards		(588)
Loss of tax benefit of state net operating loss carryforwards	1,477	1,040
Loss of tax benefit of federal tax credit carryforwards	324	495
State income taxes, net of federal benefit	(1,461)	(2,355)
Foreign rate differential	664	1,166
Valuation allowance	3,512	6,323
Derivative charge	(3,674)	(4,138)
Stock option exercises and cancellations		215
Research and development costs	(316)	(636)
Other	(16)	6
Total	$ 0	$ 0

Income Taxes - Significant Comp

Income Taxes - Significant Components of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Equity compensation	$ 84
Accrued liabilities		$ 519
Research tax credits	135	161
Lease obligation	206
Other	72	60
Net operating losses	14,502	10,624
Total deferred tax assets	14,999	11,364
Deferred tax liabilities:
Right of use asset	206
Total deferred tax liabilities	206	0
Valuation allowance	14,793	11,364	$ 5,972
Net deferred tax assets	$ 0	$ 0

Income Taxes - Summary of Chang

Income Taxes - Summary of Change in Valuation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Beginning balance	$ 11,364	$ 5,972
Charged to costs and expenses	3,512	6,323
Charged to retained earnings		(834)
Charged to other comprehensive income	(83)	(97)
Ending balance	$ 14,793	$ 11,364

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Mar. 11, 2020	Jan. 01, 2020	Feb. 29, 2020	Mar. 23, 2020	Dec. 31, 2019	Jun. 06, 2019	Dec. 31, 2018	May 31, 2018
Subsequent Event [Line Items]
Outstanding balance to vendor								$ 2.1
Common stock, par value (in dollars per share)					$ 0.01		$ 0.01
Principal							$ 4.5
Senior Secured Promissory Notes [Member]
Subsequent Event [Line Items]
Interest rate						8.00%
Principal						$ 2
Subsequent Event [Member]
Subsequent Event [Line Items]
Remaining balance payment to vendor				$ 0.9
Issue of restricted common stock for advisory services			2,717
Subsequent Event [Member] | Proposed Offering [Member]
Subsequent Event [Line Items]
Common stock, par value (in dollars per share)			$ 0.01
Number of trading days required to measure weighted average price of common stock	5 days
Subsequent Event [Member] | Proposed Offering [Member] | Rosalind [Member] | Senior Secured Promissory Notes [Member]
Subsequent Event [Line Items]
Interest rate	8.00%
Principal	$ 2
Subsequent Event [Member] | Proposed Offering [Member] | Executive Officer [Member] | Deferred Bonus [Member]
Subsequent Event [Line Items]
Unregistered shares of common stock	765,000
Subsequent Event [Member] | Proposed Offering [Member] | 2019 Annual Incentive Bonuses [Member] | Executive Officer [Member] | Support and Conversion Agreement [Member]
Subsequent Event [Line Items]
Unregistered shares of common stock	221,000
Series E and E1 Convertible Preferred Stock [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Convertible preferred stock, shares upon Conversion		2,915
Series E Preferred Stock [Member] | Subsequent Event [Member] | Proposed Offering [Member] | Rosalind [Member]
Subsequent Event [Line Items]
Conversion price	$ 1,500