Stockholders' Equity - Additional Information (Detail)

v3.19.1

Stockholders' Equity - Additional Information (Detail) - USD ($)			1 Months Ended												3 Months Ended	12 Months Ended
	Feb. 11, 2019	Jul. 03, 2018	Jun. 30, 2018	Mar. 31, 2018	Jan. 31, 2018	Dec. 31, 2017	Nov. 30, 2017	Nov. 30, 2017	Oct. 31, 2017	Jun. 30, 2017	Jun. 26, 2017	Jan. 31, 2017	Dec. 31, 2016	Sep. 30, 2015	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Jun. 01, 2018	Dec. 15, 2017	Dec. 01, 2017	Oct. 26, 2017	Jun. 01, 2017	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Based compensation, authorized number of shares																13,176,146
Employee Stock Purchase Plan to eligible employees, Reckoning fair value percentage during offering period																85.00%
Employee Stock Purchase Plan to eligible employees, compensation expense recognized																$ 200,000	$ 200,000
Share Based Compensation Restricted Stock Units																$ 13,900,000	$ 11,300,000
Common Stock, Par or Stated Value Per Share						$ 0.001									$ 0.001	$ 0.001	$ 0.001
Share Price		$ 3.04
Proceeds from Stock Options Exercised																$ 0	$ 27,000
Class of Warrant or Right, Exercise Price of Warrants or Rights						$ 8.50									$ 8.50		$ 8.50
Shares Issued, Price Per Share											$ 6.00					$ 2.50
Stock Issued During Period, Value, Issued for Services														$ 600,000		$ 500,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross																	1,900,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights											125,000
Capital Units, Authorized						100,000,000									100,000,000	100,000,000	100,000,000
Proceeds from issuance of Common stock	$ 13,100,000															$ 10,000,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options																$ 6,100,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized																7,700,000
Share-based Compensation																$ 15,012,000	$ 13,403,000
Stock Issued For Exercise Of Warrants																	10,000
Common Stock, Capital Shares Reserved for Future Issuance																643,493
Stock Issued During Period, Shares, New Issues		164,473		5,290,000					43,292							1,841,774
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period																490,000	1,128,750
Sharebased Compensation Arrangement By Sharebased Payment Award Percentage Of Shares Granted												1.00%
Stock Issued During Period, Value, New Issues							$ 25,000,000						$ 53,000,000
Payments of Stock Issuance Costs																$ 0	$ 2,804,000
Adjustments To Additional Paid In Capital At Market Offering Costs																$ 300,000
Preferred Stock, Shares Outstanding						1,000,000									1,000,000	1,000,000	1,000,000
Preferred Stock, Shares Authorized						15,000,000									15,000,000	15,000,000	15,000,000
Preferred Stock, Value, Issued						$ 1,000									$ 1,000	$ 1,000	$ 1,000
Preferred Stock, Shares Issued						1,000,000									1,000,000	1,000,000	1,000,000
Preferred Stock, Dividend Rate, Percentage							9.375%
Dividends Payable, Amount Per Share						$ 0.5839375									$ 0.5839375		$ 0.5839375
Preferred Stock, Liquidation Preference Per Share						$ 25.00									$ 25.00	$ 25.00	$ 25.00
Proceeds from Issuance of Preferred Stock and Preference Stock																$ 154,000	$ 25,000,000
Payments for Fees							$ 2,700,000	$ 100,000
Percentage of Placement of Agent Fee							3.00%										10.00%
Common Stock, Shares, Outstanding						50,991,285									50,991,285	57,845,447	50,991,285
Common Stock, Value, Issued						$ 51,000					$ 800,000				$ 51,000	$ 58,000	$ 51,000
Revenue from Contract with Customer, Including Assessed Tax																$ 23,376,000	$ 15,520,000
Common Stock, Shares, Issued						50,991,285									50,991,285	57,845,447	50,991,285
Stock Issued During Period, Value, Restricted Stock Award, Gross																	$ 0
long termincentive plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash bonus			$ 500,000
Market Offering [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from issuance of Common stock																$ 7,300,000
IPO [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Revenue from Contract with Customer, Including Assessed Tax											2,300,000
Plan 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Based compensation, authorized number of shares																10,000,000
Revenue from Contract with Customer, Including Assessed Tax																$ 2,300,000
Plan 2007 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Based compensation, authorized number of shares																6,000,000
Longterm Incentive Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value																$ 2,300,000	$ 1,500,000
Class of Warrant or Right, Outstanding						500,000									500,000		500,000
Capital Units, Authorized																100,000,000
Share-based Compensation																$ 1,300,000	$ 600,000
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners						5.00%									5.00%		5.00%
Plan 2017 and 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Based compensation, shares available for issuance																							16,000,000
Plan 2007 And 2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Based compensation, shares available for issuance																2,823,854
Series A Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued, Price Per Share							$ 25.00	$ 25.00
Preferred Stock, Shares Outstanding						1,000,000									1,000,000	1,000,000	1,000,000
Preferred Stock, Shares Authorized																					5,000,000
Preferred Stock, Value, Issued																			$ 25,000,000
Preferred Stock, Shares Issued						1,000,000									1,000,000	1,000,000	1,000,000		1,000,000
Preferred Stock, Dividend Rate, Percentage																9.375%
Dividends Payable, Amount Per Share						$ 0.299479									$ 0.299479		$ 0.299479		$ 2.34375
Preferred Stock, Liquidation Preference Per Share																$ 25.00
Proceeds from Issuance of Preferred Stock and Preference Stock							$ 22,200,000
Stock Issued During Period, Value, Restricted Stock Award, Gross																	$ 0
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock issued in connection with the first ESPP offering																110,856	67,733
Issuance of Common Stock for At the Market Offering in shares																2,914,410
Stock Issued During Period, Value, Restricted Stock Award, Gross																	$ 2,000
Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Plan Modification, Incremental Compensation Cost																	$ 2,500,000
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting year																	December 2022
Mustang [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						2,200,000									2,200,000		2,200,000
Stock Issued During Period, Value, New Issues																	$ 56,000,000
Proceeds from Fees Received																	$ 5,600,000
Percentage of Placement of Agent Fee																	10.00%
Warrants Issued on During Period																	861,077
Common Stock, Shares, Issued						8,600,000									8,600,000		8,600,000
Senior Vice President [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period, Value, Issued for Services																$ 2,300,000	$ 300,000
Mustang Bio, Inc [Member] | Market Offering [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period Shares warrants Exercised																	2,500
Stock Issued During Period, Value of Warrants Excercised																	$ 65,000
Avenue Therapeutics, Inc. [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from issuance of Common stock											$ 34,200,000
Avenue Therapeutics, Inc. [Member] | IPO [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Shares, Issued											6,325,000
Avenue Therapeutics, Inc. [Member] | Over-Allotment Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Shares, Issued											825,000
Checkpoint Therapeutics, Inc [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued, Price Per Share				$ 4.35												$ 4.33
Proceeds from issuance of Common stock				$ 20,800,000												$ 7,700,000
Stock Issued During Period, Value, New Issues				23,000,000
Payments of Stock Issuance Costs				2,200,000
Proceeds from Issuance of Preferred Stock and Preference Stock																8,000,000
Maximum Authorized Amount Of Shares To Be Sold							100,000,000	$ 100,000,000
National Holdings Corporation [Member] | Private Placement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payments of Stock Issuance Costs															$ 3,900,000
National Securities Corp [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Payments of Stock Issuance Costs				$ 1,800,000
Payments for Fees							$ 2,100,000
Dr Rosenwald [Member] | Longterm Incentive Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period					586,429							552,698
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense																5,300,000	4,000,000
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense																$ 9,700,000	9,400,000
General and Administrative Expense [Member] | Longterm Incentive Program [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation																	$ 100,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deferred Compensation Arrangement with Individual, Shares Issued																230,000	230,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Granted in Period, Fair Value																$ 6,600,000	$ 3,600,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period																1,721,802	1,325,396
Stock Issued During Period, Value, Restricted Stock Award, Gross																$ 3,300,000	$ 2,100,000
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options																3.0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Granted in Period, Fair Value																$ 1,800,000	$ 4,700,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period																294,583
Restricted Stock Units (RSUs) [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition																4 years 10 months 24 days
Restricted Stock Units (RSUs) [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition																2 years 6 months
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Stock Purchase Plan to eligible employees, Reckoning fair value percentage during offering period																85.00%		85.00%		85.00%		85.00%
Common Stock issued in connection with the first ESPP offering			43,707			45,657				22,076						67,148
Common Stock, Par or Stated Value Per Share																$ 1.04		$ 2.93		$ 3.26		$ 1.90
Share Price						$ 3.83									$ 3.83	$ 1.22	$ 3.83	$ 3.45				$ 2.24
Share-based Compensation																$ 100,000
Common Stock, Capital Shares Reserved for Future Issuance																356,507