| Property and Equipment | 9 Months Ended | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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| Sep. 30, 2021 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Property and Equipment | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Property and Equipment | Note 5 - Property and Equipment At September 30, 2021 and December 31, 2020, Mustang’s property and equipment consisted of the following: 
 
 
 Depreciation expense for the three months ended September 30, 2021, and 2020, was approximately $0.6 million and $0.4 million, respectively, and was recorded in research and development expense in the Unaudited Condensed Statements of Operations. Depreciation expense for the nine months ended September 30, 2021, and 2020, was approximately $1.5 million and $1.2 million, respectively, and was recorded in research and development expense in the Unaudited Condensed Statements of Operations. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||