Income Taxes (Schedule of Deferred Taxes Activity) (Details) (USD $) In Millions, unless otherwise specified	Sep. 26, 2014	Sep. 27, 2013
Deferred tax assets:
Accrued liabilities and reserves	$ 79.1	$ 35.5
Inventories	22.1us-gaap_DeferredTaxAssetsInventory	30.5us-gaap_DeferredTaxAssetsInventory
Tax loss and credit carryforwards	102.0	53.6
Environmental liabilities	29.5	27.3
Rebate reserves	41.1	43.4
Expired product	38.9mnk_DeferredTaxAssetsExpiredProduct	18.4mnk_DeferredTaxAssetsExpiredProduct
Postretirement benefits	36.3	31.2
Federal and state benefit of uncertain tax positions and interest	29.6	47.1
Deferred intercompany interest	0	19.2
Share-based compensation	28.0	12.3
Other	31.5us-gaap_DeferredTaxAssetsOther	25.6us-gaap_DeferredTaxAssetsOther
Total deferred tax assets, gross	438.1us-gaap_DeferredTaxAssetsGross	344.1us-gaap_DeferredTaxAssetsGross
Deferred tax liabilities:
Property, plant and equipment	(110.0)	(160.5)
Intangible assets	(2,176.5)	(113.1)
Installment sale	(93.5)	0
Investment in partnership	(191.3)	(173.6)
Total deferred tax liabilities, gross	(2,571.3)us-gaap_DeferredIncomeTaxLiabilities	(447.2)us-gaap_DeferredIncomeTaxLiabilities
Net deferred tax (liability) asset before valuation allowances	(2,133.2)	(103.1)
Valuation allowances	(77.5)	(30.0)
Net deferred tax (liability) asset	$ (2,210.7)us-gaap_DeferredTaxAssetsLiabilitiesNet	$ (133.1)us-gaap_DeferredTaxAssetsLiabilitiesNet

Deferred Tax Assets, Deferred Intercompany Interest

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Deferred Tax Assets, Federal and State Benefit of Uncertain Tax Positions and Interest

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Net Deferred Tax Assets, before Valuation Allowances

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Amount of deferred tax liability attributable to taxable temporary differences.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from inventory.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences not separately disclosed.

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The tax effect as of the balance sheet date of the amount of future tax deductions arising from all unused tax credit carryforwards which have been reduced by a valuation allowance.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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Amount of deferred tax liability attributable to taxable temporary differences from intangible assets other than goodwill.

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Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment.

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