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License, Clinical Trial and Sponsored Research Agreements (Other - Sponsored Research and Clinical Trial Agreements) (Narrative) (Details) - USD ($) $ in Thousands |  |  | 1 Months Ended | 3 Months Ended | 9 Months Ended
--- | --- | --- | --- | --- | ---
Jul. 01, 2020 | Jul. 03, 2017 | Jun. 30, 2021 | Nov. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020 | Sep. 30, 2021 | Sep. 30, 2020
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |
Research and development expense |  |  |  |  | $ 14,083 | $ 7,987 | $ 36,603 | $ 27,131
Sponsored Research and Clinical Trial Agreements [Member] |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |
Research and development expense |  |  |  |  | 1,756 | 734 | 4,858 | 4,900
Fred Hutchinson Cancer Research Center [Member] | Sponsored Research and Clinical Trial Agreements [Member] | CD20 (MB-106) [Member] |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |
Milestones payable |  | $ 5,300 |  |  |  |  |  |
Additional milestone payments |  |  |  | $ 800 |  |  |  |
Research and development expense |  |  |  |  | 492 | 418 | 1,490 | 1,134
St. Jude Children's Research Hospital [Member] | Sponsored Research and Clinical Trial Agreements [Member] | ST. Jude - XSCID [Member] |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |
Upfront fees paid | $ 1,100 |  |  |  |  |  |  |
Research and development expense |  |  |  |  | 330 | 107 | 610 | 1,665
Mayo Clinic [Member] | Sponsored Research and Clinical Trial Agreements [Member] |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |
Research and development expense |  |  |  |  | 231 | $ 0 | 464 | $ 0
Mayo Clinic [Member] | Sponsored Research and Clinical Trial Agreements [Member] | Car T Technology [Member] |  |  |  |  |  |  |  |
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items] |  |  |  |  |  |  |  |
Milestones payable |  |  | $ 2,100 |  |  |  |  |
Research and development expense |  |  |  |  | $ 200 |  | $ 500 |
Agreement term |  |  | 2 years |  |  |  |  |

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- Definition The costs incurred in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, excluding in-process research and development acquired in a business combination consummated during the period. Excludes software research and development, which has a separate concept. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 730 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6420194&loc=d3e21568-108373 + Details
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