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Period Type:

Acquisitions (Details) $ / shares in Units, $ in Thousands, € in Millions										1 Months Ended		3 Months Ended			6 Months Ended		12 Months Ended
	Aug. 03, 2026 $ / shares	Jul. 21, 2025 USD ($)	Apr. 01, 2025 USD ($)	Jul. 03, 2024 USD ($)	Jul. 03, 2024 EUR (€)	Jul. 02, 2024 USD ($)	Jun. 27, 2024 EUR (€)	Jun. 15, 2024 USD ($) LicensedAsset	Jan. 08, 2024 USD ($)	Apr. 30, 2026 USD ($)	Nov. 30, 2025 USD ($)	Jun. 30, 2026 USD ($) shares	Jun. 30, 2025 USD ($)	Sep. 30, 2024 USD ($) shares	Jun. 30, 2026 USD ($) shares	Jun. 30, 2025 USD ($)	Dec. 31, 2025 USD ($) shares	Dec. 31, 2024 USD ($)	Mar. 06, 2024 $ / shares shares	Jan. 22, 2024 $ / shares shares
Asset Acquisition [Line Items]
Additional cash payment required												$ 65,041			$ 65,041		$ 94,339
Research and development												$ 38,202	$ 45,489		$ 77,581	$ 81,803
Radiopharm Theranostics Limited
Asset Acquisition [Line Items]
Shares owned (in shares) \| shares												537,958,513		149,625,180	537,958,513
Shares Purchase (in shares) \| shares																	388,333,333
Purchase amount in investment in equity securities														$ 5,000			$ 10,000
Perspective Therapeutics, Inc
Asset Acquisition [Line Items]
Subsidiary, ownership percentage, noncontrolling owner																			19.90%
Shares owned (in shares) \| shares												11,677,339			11,677,339
Perspective Therapeutics, Inc \| Licenses
Asset Acquisition [Line Items]
Acquisition of exclusive license option									$ 28,000
Perspective Therapeutics, Inc, Fully Diluted Basis
Asset Acquisition [Line Items]
Subsidiary, ownership percentage, noncontrolling owner																			17.35%
Perspective Common Stock
Asset Acquisition [Line Items]
Shares acquired (in shares) \| shares																			60,431,039	56,342,355
Percentage of acquired interest																				11.39%
Share price (in dollars per share) \| $ / shares																			$ 0.95	$ 0.37
Evergreen Theragnostics
Asset Acquisition [Line Items]
Payments to acquire businesses			$ 276,400
Additional cash payment required			25,000
Acquisition and integration related costs												$ 0	$ 14,700		$ 1,900	$ 17,200
Payment of transaction expenses			11,600
Nonrecurring post combination expense															7,500
Component of consideration transferred			$ 6,100
Business Combination, Separately Recognized Transaction, Acquisition-Related Cost, Expensed, Statement of Income or Comprehensive Income [Extensible Enumeration]			Operating Expenses Before Gain Loss On Sale Of Assets
Pre existing debt			$ 4,300
Agreement and Plan of Merger with Curium Pharma \| Subsequent Event
Asset Acquisition [Line Items]
Share price (in dollars per share) \| $ / shares	$ 102.5
Date of Merger Agreement	Aug. 03, 2026
Additional Milestone Payments \| Evergreen Theragnostics
Asset Acquisition [Line Items]
Additional cash payment required			$ 727,500
Regulatory Milestones \| RM2 Sublicense Agreement [Member]
Asset Acquisition [Line Items]
Payment for acquisitions \| €							€ 10.0
Radiopharm Theranostics Limited
Asset Acquisition [Line Items]
Payment for acquisitions								$ 2,000
Asset acquisition, additional milestone payments								$ 20,000
Number of licensed asset acquired \| LicensedAsset								2
Radiopharm Theranostics Limited \| Sales Milestones
Asset Acquisition [Line Items]
Asset acquisition, additional milestone payments								$ 6,500
Life Molecular Imaging, RM2 Technology
Asset Acquisition [Line Items]
Research and development																	11,200	$ 36,000
Payment for acquisitions				$ 35,000		$ 1,000
Contingent regulatory and development milestones maximum amount \| €					€ 45.0
Contingent regulatory and development milestones minimum amount \| €					82.5
Life Molecular Imaging, RM2 Technology \| Sales Milestones
Asset Acquisition [Line Items]
Asset acquisition, additional milestone payments \| €					280.0
Life Molecular Imaging, RM2 Technology \| Regulatory Milestones
Asset Acquisition [Line Items]
Asset acquisition, additional milestone payments \| €					€ 127.5
Lantheus Biosciences Ltd
Asset Acquisition [Line Items]
Acquisition and integration related costs												$ 1,900			3,800		$ 36,700
Payment for acquisitions		$ 355,200
Payment of working capital settlement in business combination											$ 2,300
Additional working capital settlement received										$ 300
Total adjustments to purchase consideration															$ 2,600
Asset acquisition, additional milestone payments		$ 400,000