Income Taxes (Schedule of Income Tax Receivables and Other Assets) (Details) - USD ($) $ in Millions	Dec. 27, 2024	Dec. 29, 2023
Income Tax Disclosure [Abstract]
Prepaid expenses and other current assets	$ 56.5	$ 11.5

Deferred Tax Assets, Prepaid And Other Current Assets

No definition available.

Name:	mnk_DeferredTaxAssetsPrepaidAndOtherCurrentAssets
Namespace Prefix:	mnk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant