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Asset Acquisition, Cash Consideration Transferred, Holdback Amount

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Asset Acquisition, Consideration Transferred, Cash Consideration

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Asset Acquisition, Consideration Transferred, Upfront Cash Consideration

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Asset Acquisition, Consideration Transferred, Shares Of Upfront Equity Consideration,

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Asset Acquisition, Equity Consideration Transferred, Holdback Shares

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Asset Acquisition, Net Assets Acquired

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Asset acquisitions.

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- Definition

Clinical development and regulatory milestone payments payable.

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Clinical development and regulatory milestone payments payable upon commercialization.

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Clinical development and regulatory milestone payments payable upon regulatory approval.

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Collaborative Arrangement, Rights and Obligations, Contingent Milestone Payments

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Collaborative Arrangement, Rights and Obligations, Maximum Aggregate Commercial Milestone Payments

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Collaborative Arrangement, Rights and Obligations, Maximum Aggregate Development Milestone Payments

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Collaborative Arrangement, Rights and Obligations, Maximum Aggregate Milestone Payments

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Development or regulatory milestones incurred

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License agreement milestone amount accrued.

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License agreement milestone amount payable.

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Milestone payment payable upon achievement of product sales.

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Number of product candidates.

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Payments For Achievement Of Various Clinical Development, Regulatory And Commercial Milestones

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Payments For Achievement Of Contingent Milestones

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Payments For Achievement Of Product And Sales Milestones

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Royalty payment obligations period.

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Royalty Payment Period Term

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Amount of consideration transferred in asset acquisition. Includes, but is not limited to, cash, liability incurred by acquirer, and equity interest issued by acquirer.

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Amount of contingent consideration recognized as part of consideration transferred in asset acquisition.

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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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The cash outflows from the purchase of net carrying value allocated to in-process research and development costs and materials acquired in a business combination.

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The cash outflow to acquire asset without physical form usually arising from contractual or other legal rights, excluding goodwill.

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Amount of expense for research and development. Excludes cost for computer software product to be sold, leased, or otherwise marketed, writeoff of research and development assets acquired in transaction other than business combination or joint venture formation or both, and write-down of intangible asset acquired in business combination or from joint venture formation or both, used in research and development activity.

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Asset Acquisitions - Narrative (Details)			1 Months Ended			3 Months Ended		6 Months Ended
Asset Acquisitions - Narrative (Details)	Jan. 23, 2026 USD ($) shares	Aug. 31, 2023 USD ($)	Apr. 30, 2026 USD ($)	Oct. 31, 2024 USD ($)	Nov. 30, 2018 USD ($) productCandidate	Jun. 30, 2026 USD ($)	Jun. 30, 2025 USD ($)	Jun. 30, 2026 USD ($)	Jun. 30, 2025 USD ($)	Dec. 31, 2025 USD ($)
Asset Acquisitions [Line Items]
Payments for intangible assets								$ 35,000,000	$ 0
Stock-based compensation expense						$ 30,575,000	$ 18,468,000	88,049,000	34,271,000
Selling, general and administrative						81,469,000	63,286,000	177,799,000	120,992,000
Research and development						90,528,000	46,067,000	188,438,000	87,111,000
Livmarli
Asset Acquisitions [Line Items]
Royalty payment period term					10 years
Travere Therapeutics, Inc. \| Shire Agreement
Asset Acquisitions [Line Items]
Achievement of product sales milestones						25,000,000.0		25,000,000.0
Shire \| Livmarli
Asset Acquisitions [Line Items]
Development or regulatory milestones incurred						0	0	0	0
Shire \| Shire Agreement \| Livmarli
Asset Acquisitions [Line Items]
License agreement milestone amount accrued										$ 10,000,000.0
Income Statement Location [Axis]: us-gaap:ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCost
Asset Acquisitions [Line Items]
Stock-based compensation expense						14,227,000	7,624,000	38,416,000	12,853,000
Income Statement Location [Axis]: us-gaap:SellingGeneralAndAdministrativeExpense
Asset Acquisitions [Line Items]
Stock-based compensation expense						15,887,000	10,606,000	48,824,000	20,849,000
Income Statement Location [Axis]: mirm:CostOfSales
Asset Acquisitions [Line Items]
Stock-based compensation expense						461,000	238,000	809,000	569,000
Bluejay Employee Stock Awards \| Income Statement Location [Axis]: us-gaap:ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCost
Asset Acquisitions [Line Items]
Stock-based compensation expense								15,400,000
Bluejay Employee Stock Awards \| Income Statement Location [Axis]: us-gaap:SellingGeneralAndAdministrativeExpense
Asset Acquisitions [Line Items]
Stock-based compensation expense								19,300,000
Incyte Corporation
Asset Acquisitions [Line Items]
Total purchase consideration						16,400,000		16,400,000
Bluejay Acquisition
Asset Acquisitions [Line Items]
Contingent consideration	$ 200,000,000.0
Upfront equity consideration (in shares) \| shares	4,517,062
Upfront cash consideration	$ 241,200,000
Equity consideration holdback (in shares) \| shares	522,375
Cash consideration holdback	$ 24,800,000
Cash consideration holdback payable upon finalization of working capital adjustments	1,000,000.0
Acquired in-process research and development								726,300,000
Net assets acquired	44,800,000
Bluejay Acquisition \| Bluejay Employee Stock Awards
Asset Acquisitions [Line Items]
Stock-based compensation expense								34,700,000
Bluejay Acquisition \| Bluejay Employee Stock Awards \| Income Statement Location [Axis]: us-gaap:ResearchAndDevelopmentExpenseExcludingAcquiredInProcessCost
Asset Acquisitions [Line Items]
Stock-based compensation expense								15,400,000
Bluejay Acquisition \| Bluejay Employee Stock Awards \| Income Statement Location [Axis]: us-gaap:SellingGeneralAndAdministrativeExpense
Asset Acquisitions [Line Items]
Stock-based compensation expense								19,300,000
Bluejay Therapeutics, Inc.
Asset Acquisitions [Line Items]
Total purchase consideration	771,076,000
Cash consideration, including cash paid in lieu of equity to satisfy taxes	274,814,000
Cash and cash equivalents	54,335,000
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement \| Incyte Corporation
Asset Acquisitions [Line Items]
Payments for intangible assets			$ 16,000,000.0
Contingent consideration			48,000,000.0
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement \| Incyte Corporation \| FDA Approval
Asset Acquisitions [Line Items]
Contingent consideration			25,000,000.0
Collaborative Arrangement, Transaction with Party to Collaborative Arrangement \| Incyte Corporation \| Commerical Milestones
Asset Acquisitions [Line Items]
Contingent consideration			$ 15,000,000.0
Asset Purchase Agreement \| Bile Acid Medicines \| Travere Therapeutics, Inc.
Asset Acquisitions [Line Items]
Payments for acquisition		$ 210,400,000
Product sales milestone payments, payable		$ 235,000,000.0
Shire Agreement \| Livmarli
Asset Acquisitions [Line Items]
Milestones accrued							5,000,000.0		5,000,000.0
Shire Agreement \| Shire
Asset Acquisitions [Line Items]
Product sales milestone payments, payable					$ 30,000,000.0
Number of product candidates \| productCandidate					2
Shire Agreement \| Shire \| Livmarli
Asset Acquisitions [Line Items]
Milestone payments, payable					$ 109,500,000
Milestone payments, payable upon approval					25,000,000.0
Shire Agreement \| Shire \| Volixibat
Asset Acquisitions [Line Items]
Milestone payments, payable upon commercialization					30,000,000.0
Payments and accruals for achievement of various clinical development, regulatory and commercial milestones								101,500,000
Assignment And Licence Agreement, FDA \| Livmarli
Asset Acquisitions [Line Items]
Milestones accrued							10,000,000.0		10,000,000.0
Assignment And Licence Agreement, European Medicines Agency \| Livmarli
Asset Acquisitions [Line Items]
Milestones accrued							$ 10,000,000.0		$ 10,000,000.0
Novartis Pharma AG \| Assigned License Agreement
Asset Acquisitions [Line Items]
Development milestones	4,000,000.0
Commercial milestones	27,000,000.0
Contingent milestones	$ 4,000,000.0
Payment for contingent milestones						4,000,000.0		4,000,000.0
Enthorin Therapeutics, LLC and Dart Neuroscience LLC \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement
Asset Acquisitions [Line Items]
Payments for intangible assets				$ 7,500,000
Additional payments to acquire intangible assets				$ 217,500,000
Sanofi-Aventis Deutschland GmbH \| Assigned License Agreement
Asset Acquisitions [Line Items]
Milestone payments, payable					$ 36,000,000.0
Milestones accrued						$ 0		$ 0
Royalty obligations payment period					10 years