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

License, Clinical Trial and Sponsored Research Agreements (City of Hope - Sponsored Research and Clinical Trial Agreements) (Narrative) (Details)

License, Clinical Trial and Sponsored Research Agreements (City of Hope - Sponsored Research and Clinical Trial Agreements) (Narrative) (Details)			1 Months Ended							12 Months Ended
	Apr. 01, 2021 USD ($)	Jul. 03, 2017 USD ($)	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Nov. 30, 2020 USD ($)	Oct. 31, 2020 USD ($)	Jun. 30, 2020 USD ($)	Feb. 28, 2017 USD ($)	Mar. 31, 2015 USD ($) item	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development expense										$ 49,864,000	$ 37,237,000
Mayo Clinic [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront fees paid	$ 800,000
Sponsored Research and Clinical Trial Agreements [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development expense										6,591,000	7,717,000
Sponsored Research and Clinical Trial Agreements [Member] \| City of Hope National Medical Center ("COH") [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones payable									$ 2,000,000.0
Number of installments \| item									4
Research and development expense										0	500,000
Sponsored Research and Clinical Trial Agreements [Member] \| Mayo Clinic [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones payable			$ 2,100,000
Agreement term			2 years
Research and development expense										695,000	0
Sponsored Research and Clinical Trial Agreements [Member] \| CD123 (MB-102) [Member] \| City of Hope National Medical Center ("COH") [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront fees paid								$ 19,450
Milestones payable								200,000
Contribution per patient								$ 97,490
Agreement term								3 years
Research and development expense										301,000	433,000
Sponsored Research and Clinical Trial Agreements [Member] \| CS1 (MB-104) [Member] \| City of Hope National Medical Center ("COH") [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development expense										608,000	885,000
Sponsored Research and Clinical Trial Agreements [Member] \| CS1 (MB-104) [Member] \| City of Hope National Medical Center ("COH") [Member] \| Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones payable							$ 2,400,000
Sponsored Research and Clinical Trial Agreements [Member] \| IL13Ra2 (MB-101) [Member] \| City of Hope National Medical Center ("COH") [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront fees paid						$ 29,000		$ 9,300
Milestones payable								200,000
Contribution toward patient costs								$ 100,000
Contribution per patient						100,000
Agreement term								3 years
Research and development expense										1,169,000	530,000
Annual maintenance fee payable				$ 200,000		200,000
Sponsored Research and Clinical Trial Agreements [Member] \| PSCA (MB-105) [Member] \| City of Hope National Medical Center ("COH") [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones payable						33,000
Research and development expense										107,000	204,000
Sponsored Research and Clinical Trial Agreements [Member] \| PSCA (MB-105) [Member] \| City of Hope National Medical Center ("COH") [Member] \| Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones payable						2,300,000
Sponsored Research and Clinical Trial Agreements [Member] \| HER2 (MB 103) [Member] \| City of Hope National Medical Center ("COH") [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones payable						29,375
Research and development expense										697,000	1,519,000
Sponsored Research and Clinical Trial Agreements [Member] \| HER2 (MB 103) [Member] \| City of Hope National Medical Center ("COH") [Member] \| Maximum
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones payable						$ 3,000,000.0
Sponsored Research and Clinical Trial Agreements [Member] \| CD20 (MB-106) [Member] \| Fred Hutchinson Cancer Research Center [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Milestones payable		$ 5,300,000
Additional milestone payments					$ 1,800,000
Research and development expense										1,979,000	1,804,000
Sponsored Research and Clinical Trial Agreements [Member] \| ST. Jude - XSCID [Member] \| St. Jude Children's Research Hospital [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development expense										$ 865,000	$ 1,842,000