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Basis of Presentation and Significant Accounting Policies - Purchase of Rights to Future Milestones and Royalties and Income Taxes and Net Income (Loss) per Share (Details) - USD ($) $ in Millions | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2021 | Dec. 31, 2020
Purchase of Rights to Future Milestones and Royalties |  |
Impairment of long-term royalty receivable | $ 0.0 | $ 0.0
Income tax penalties or interest charged | $ 0.0 |

X
- Definition Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32718-109319 + Details
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