Mustang Bio, Inc. Annual report pursuant to Section 13 and 15(d)

Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity (Details)

Stockholders' Equity (Details)					1 Months Ended				12 Months Ended
Stockholders' Equity (Details)	Jan. 01, 2020	Jan. 01, 2019	Jul. 31, 2016 $ / shares shares	Jul. 26, 2016	Nov. 30, 2019 shares	May 31, 2019 USD ($) shares	Apr. 30, 2019 USD ($) $ / shares shares	Mar. 29, 2019 shares	Dec. 31, 2019 USD ($) item $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Sep. 30, 2019 shares	Aug. 16, 2019 $ / shares shares	Aug. 15, 2019 shares	Jul. 31, 2018 USD ($)	Dec. 31, 2016 USD ($) shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized			50,000,000						85,000,000	85,000,000		85,000,000	50,000,000
Common stock par value (in dollars per share) \| $ / shares			$ 0.0001						$ 0.0001	$ 0.0001
Common stock issuable, shares									1,206,667	709,314
Aggregate value of shares subscribed \| $									$ 4,923,000	$ 2,085,000
Common stock, number of shares issued									39,403,519	26,610,183
Issuance of common shares, net of offering costs - Public Offering \| $									$ 29,537,000
Proceeds from issuance of common stock and warrants, offering cost \| $									2,088,000	$ 0
Stock dividend (as a percent)	2.50%	2.00%	2.50%
Fortress Biotech, Inc
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate value of shares subscribed \| $															$ 900
Stock dividend (as a percent)				2.50%
At The Market Offering
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from issuance of common shares \| $									$ 22,000,000
Maximum value of shares authorized to sell at offering \| $														$ 75,000,000
Agent commission (as a percent)														3.00%
Common stock, number of shares issued									3,500,000
Share price \| $ / shares									$ 6.42
Issuance of common shares, net of offering costs - Public Offering \| $									$ 22,500,000
Proceeds from issuance of common stock and warrants, offering cost \| $									500,000
At The Market Offering \| Fortress Biotech, Inc
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share of equity or debt financing used to calculate equity fee or stock issuance to maintain parity (as a percent)						2.50%	2.50%
Shares issued for services (in shares)						197,656	87,656
Proceeds from issuance of common shares \| $						$ 31,600,000	$ 22,500,000
Issuances Related To Debt Financing \| Fortress Biotech, Inc
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued for services (in shares)								108,069
Stock dividend (as a percent)								2.50%
Public Offering
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from issuance of common shares \| $							$ 29,500,000
Maximum value of shares authorized to sell at offering \| $									75,000,000
Securities available for sale \| $									$ 20,900,000
Share price \| $ / shares							$ 4.00
Issuance of common shares and warrants for cash (in shares)							6,875,000
Issuance of common shares, net of offering costs - Public Offering \| $							$ 31,600,000
Proceeds from issuance of common stock and warrants, offering cost \| $							$ 2,100,000
Over-Allotment Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common shares and warrants for cash (in shares)							1,031,250
Common Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized											85,000,000
Common stock par value (in dollars per share) \| $ / shares												$ 0.0001
Number of votes per share \| item									1
Common Shares \| City Of Hope National Medical Center ("COH") [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued in conversion					17,007		137,608
Common Shares \| Fortress Biotech, Inc
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock issuable, shares															2,000,000
Class A Common Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued for services (in shares)									0	0
Number of shares converted									(154,615)
Common stock, shares authorized			1,000,000
Director appointment right, period									10 years
Number of directors appointable \| item									1
Common stock, number of shares issued									845,385	1,000,000
Issuance of common shares and warrants for cash (in shares)									0
Issuance of common shares, net of offering costs - Public Offering \| $									$ 0
Class A Common Shares \| City Of Hope National Medical Center ("COH") [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares converted					17,007		137,608		154,615
Common Class B
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized			15,000,000
Number of votes per share \| item									1.1
Common Class B \| Fortress Biotech, Inc
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock issuable, shares															7,000,000