Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Common Stock Issued [Member]	In Treasury [Member]	Additional Paid-in Capital [Member]	Accumulated deficit [Member]	Accumulated Other Comprehensive (loss) income [Member]	Total
Balance at Dec. 31, 2011	$ 30	$ (51)	$ 173,065	$ (146,940)	$ 0	$ 26,104us-gaap_StockholdersEquity
Balance (in shares) at Dec. 31, 2011	3,023,374	(1,757)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation expense for issuance of stock options	0	0	2,807	0	0	2,807
Compensation expense for issuance of restricted stock	0	0	1,018	0	0	1,018
Compensation expense for issuance of restricted stock (in shares)	25,543	0
Sale of common stock, net of expenses	16	0	37,231	0	0	37,247
Sale of common stock, net of expenses (in shares)	1,576,704	0
Exercise of warrants	2	0	4,432	0	0	4,434
Exercise of warrants (in shares)	185,967
Fair value of warrants exercised	0	0	908	0	0	908dcth_FairValueOfWarrantsExercised
Fair value of warrants issued classified as liability	0	0	(678)	0	0	(678)
Net loss	0	0	0	(51,868)	0	(51,868)us-gaap_NetIncomeLoss
Foreign currency translation	0	0	0	0	37	37
Balance at Dec. 31, 2012	48	(51)	218,783	(198,808)	37	20,009us-gaap_StockholdersEquity
Balance (in shares) at Dec. 31, 2012	4,811,588	(1,757)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation expense for issuance of stock options	0	0	174	0	0	174
Compensation expense for issuance of restricted stock	0	0	117	0	0	117
Compensation expense for issuance of restricted stock (in shares)	8,604	0
Sale of common stock, net of expenses	36	0	41,424	0	0	41,460
Sale of common stock, net of expenses (in shares)	3,570,061	0
Exercise of warrants	0	0	243	0	0	243
Exercise of warrants (in shares)	12,669	0
Fair value of warrants exercised	0	0	218	0	0	218dcth_FairValueOfWarrantsExercised
Fair value of warrants issued classified as liability	0	0	(1,857)	0	0	(1,857)
Net loss	0	0	0	(30,324)	0	(30,324)us-gaap_NetIncomeLoss
Foreign currency translation	0	0	0	0	59	59
Balance at Dec. 31, 2013	84	(51)	259,102	(229,132)	96	30,099us-gaap_StockholdersEquity
Balance (in shares) at Dec. 31, 2013	8,402,922	(1,757)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation expense for issuance of stock options	0	0	391	0	0	391
Compensation expense for issuance of restricted stock	0	0	100	0	0	100
Compensation expense for issuance of restricted stock (in shares)	28,256	0
Sale of common stock, net of expenses	13	0	4,730	0	0	4,743
Sale of common stock, net of expenses (in shares)	1,260,079	0
Exercise of warrants	0	0	126	0	0	126
Exercise of warrants (in shares)	49,137	0
Fair value of warrants exercised	0	0	143	0	0	143dcth_FairValueOfWarrantsExercised
Net loss	0	0	0	(17,381)	0	(17,381)us-gaap_NetIncomeLoss
Foreign currency translation	0	0	0	0	(76)	(76)
Balance at Dec. 31, 2014	$ 97	$ (51)	$ 264,592	$ (246,513)	$ 20	$ 18,145us-gaap_StockholdersEquity
Balance (in shares) at Dec. 31, 2014	9,740,394	(1,757)

The fair value of warrants exercised during the period.

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Number of shares of stock issued during the period pursuant to the exercise of stock options.

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Value of stock issued pursuant to the exercise of warrants during the period.

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This element represents the amount of recognized equity-based compensation related to stock options during the period, that is, the amount recognized as expense in the income statement (or as asset if compensation is capitalized).

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Number of shares issued which are neither cancelled nor held in the treasury.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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Number of shares issued during the period related to Restricted Stock Awards, net of any shares forfeited.

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Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering.

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Value of stock related to Restricted Stock Awards issued during the period, net of the stock value of such awards forfeited.

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