Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Statements of Cash Flows) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
Mar. 27, 2015	Mar. 28, 2014
Cash Flows From Operating Activities:
Net cash provided by (used in) operating activities	$ 365.5	$ 141.2
Cash Flows From Investing Activities:
Capital expenditures	(55.1)	(50.7)
Intercompany loan investment	0mnk_IntercompanyLoanInvestment	0mnk_IntercompanyLoanInvestment
Investment in subsidiary	0	0
Acquisitions and intangibles, net of cash acquired	0	(1,293.2)
Restricted cash	0.4	4.1
Other	1.7	8.0
Net cash (used in) provided by investing activities	(53.0)	(1,331.8)
Cash Flows From Financing Activities:
Issuance of external debt	80.0us-gaap_ProceedsFromIssuanceOfDebt	1,296.8us-gaap_ProceedsFromIssuanceOfDebt
Repayment of external debt and capital leases	(63.5)	(30.8)
Debt financing costs	(0.4)us-gaap_PaymentsOfFinancingCosts	(32.2)us-gaap_PaymentsOfFinancingCosts
Excess tax benefit from share-based compensation	20.2	4.0
Proceeds from exercise of share options	20.6	16.1
Repurchase of shares	(12.3)	(1.8)
Intercompany loan borrowings, net	0mnk_ProceedsFromIntercompanyBorrowings	0mnk_ProceedsFromIntercompanyBorrowings
Capital contribution	0us-gaap_ProceedsFromContributedCapital	0us-gaap_ProceedsFromContributedCapital
Other	4.0	0
Net cash provided (used in) by financing activities	40.6	1,252.1
Effect of currency rate changes on cash	(7.4)	(2.1)
Net increase in cash and cash equivalents	345.7	59.4
Cash and cash equivalents at beginning of period	707.8	275.5
Cash and cash equivalents at end of period	1,053.5	334.9
Mallinckrodt plc
Cash Flows From Operating Activities:
Net cash provided by (used in) operating activities	120.7	8.6
Cash Flows From Investing Activities:
Capital expenditures	0	0
Intercompany loan investment	(127.3)	(21.5)
Investment in subsidiary	0	0
Acquisitions and intangibles, net of cash acquired		0
Restricted cash	0	0
Other	0	0
Net cash (used in) provided by investing activities	(127.3)	(21.5)
Cash Flows From Financing Activities:
Issuance of external debt	0	0
Repayment of external debt and capital leases	0	0
Debt financing costs	0	0
Excess tax benefit from share-based compensation	0	0
Proceeds from exercise of share options	20.6	16.1
Repurchase of shares	(12.3)	(1.8)
Intercompany loan borrowings, net	0	(2.4)
Capital contribution	0	0
Other	0	0
Net cash provided (used in) by financing activities	8.3	11.9
Effect of currency rate changes on cash	0	0
Net increase in cash and cash equivalents	1.7	(1.0)
Cash and cash equivalents at beginning of period	0.3	1.2
Cash and cash equivalents at end of period	2.0	0.2
Mallinckrodt International Finance S.A.
Cash Flows From Operating Activities:
Net cash provided by (used in) operating activities	(78.3)	(17.1)
Cash Flows From Investing Activities:
Capital expenditures	0	0
Intercompany loan investment	0	2.4
Investment in subsidiary	(124.9)	(1,300.0)
Acquisitions and intangibles, net of cash acquired		0
Restricted cash	0	0
Other	0	0
Net cash (used in) provided by investing activities	(124.9)	(1,297.6)
Cash Flows From Financing Activities:
Issuance of external debt	0	1,296.8
Repayment of external debt and capital leases	(8.2)	0
Debt financing costs	0	(32.2)
Excess tax benefit from share-based compensation	0	0
Proceeds from exercise of share options	0	0
Repurchase of shares	0	0
Intercompany loan borrowings, net	462.9	80.3
Capital contribution	0	0
Other	0	0
Net cash provided (used in) by financing activities	454.7	1,344.9
Effect of currency rate changes on cash	0	0
Net increase in cash and cash equivalents	251.5	30.2
Cash and cash equivalents at beginning of period	18.5	56.5
Cash and cash equivalents at end of period	270.0	86.7
Other Subsidiaries
Cash Flows From Operating Activities:
Net cash provided by (used in) operating activities	323.1	149.7
Cash Flows From Investing Activities:
Capital expenditures	(55.1)	(50.7)
Intercompany loan investment	(335.6)	(58.8)
Investment in subsidiary	0	0
Acquisitions and intangibles, net of cash acquired		(1,293.2)
Restricted cash	0.4	4.1
Other	1.7	8.0
Net cash (used in) provided by investing activities	(388.6)	(1,390.6)
Cash Flows From Financing Activities:
Issuance of external debt	80.0	0
Repayment of external debt and capital leases	(55.3)	(30.8)
Debt financing costs	(0.4)	0
Excess tax benefit from share-based compensation	20.2	4.0
Proceeds from exercise of share options	0	0
Repurchase of shares	0	0
Intercompany loan borrowings, net	0	0
Capital contribution	124.9	1,300.0
Other	4.0	0
Net cash provided (used in) by financing activities	165.4	1,273.2
Effect of currency rate changes on cash	(7.4)	(2.1)
Net increase in cash and cash equivalents	92.5	30.2
Cash and cash equivalents at beginning of period	689.0	217.8
Cash and cash equivalents at end of period	781.5	248.0
Eliminations
Cash Flows From Operating Activities:
Net cash provided by (used in) operating activities	0	0
Cash Flows From Investing Activities:
Capital expenditures	0	0
Intercompany loan investment	462.9	77.9
Investment in subsidiary	124.9	1,300.0
Acquisitions and intangibles, net of cash acquired		0
Restricted cash	0	0
Other	0	0
Net cash (used in) provided by investing activities	587.8	1,377.9
Cash Flows From Financing Activities:
Issuance of external debt	0	0
Repayment of external debt and capital leases	0	0
Debt financing costs	0	0
Excess tax benefit from share-based compensation	0	0
Proceeds from exercise of share options	0	0
Repurchase of shares	0	0
Intercompany loan borrowings, net	(462.9)	(77.9)
Capital contribution	(124.9)	(1,300.0)
Other	0	0
Net cash provided (used in) by financing activities	(587.8)	(1,377.9)
Effect of currency rate changes on cash	0	0
Net increase in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	$ 0	$ 0

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