Incremental percentage increase (decrease) in the stated rate on a debt instrument.

No definition available.

Name:	us-gaap_DebtInstrumentInterestRateIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the aggregate of total long-term debt, including current maturities and short-term debt.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtLongtermAndShorttermCombinedAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Weighted average interest rate of long-term debt outstanding calculated at point in time.

+ References

No definition available.

+ Details

Name:	us-gaap_LongtermDebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_SecuredDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_DebtInstrumentAxis=mnk_TermLoandueSept2024Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mnk_TermLoandue2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mnk_A2017RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mnk_FixedRateInstrumentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mnk_A2017ReplacementTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=mnk_A2018ReplacementTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SecuredDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=mnk_TermLoansdueSept2024andFeb2025Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt Schedule of Outstanding Borrowings and Applicable Rates (Details) - USD ($) $ in Millions	Oct. 12, 2020	Dec. 30, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Debt, Long-term and Short-term, Combined Amount		$ 3,092.6	$ 5,145.8
Term Loan due Sept 2024 [Member]
Debt Instrument [Line Items]
Secured Debt		0.0	1,396.5
Term Loan due 2025 [Member]
Debt Instrument [Line Items]
Secured Debt		0.0	370.7
2017 Revolving Credit Facility
Debt Instrument [Line Items]
Secured Debt		$ 0.0	900.0
Fixed-rate instruments
Debt Instrument [Line Items]
Long-term Debt, Weighted Average Interest Rate, at Point in Time		10.54%
Debt, Long-term and Short-term, Combined Amount		$ 1,795.2
2017 Replacement Term Loan
Debt Instrument [Line Items]
Long-term Debt, Weighted Average Interest Rate, at Point in Time		9.99%
Debt, Long-term and Short-term, Combined Amount		$ 1,374.1
Secured Debt		$ 1,222.1	0.0
2018 Replacement Term Loan
Debt Instrument [Line Items]
Long-term Debt, Weighted Average Interest Rate, at Point in Time		10.24%
Debt, Long-term and Short-term, Combined Amount		$ 364.8
Secured Debt		$ 326.9	$ 0.0
Secured Debt
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Increase (Decrease)	200.00%
Term Loans due Sept 2024 and Feb 2025 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Increase (Decrease)	250.00%