Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Millions	6 Months Ended
	Mar. 25, 2016	Mar. 27, 2015
Cash Flows From Operating Activities:
Net cash provided by operating activities	$ 540.1	$ 365.5
Cash Flows From Investing Activities:
Capital expenditures	(91.4)	(55.1)
Cash paid with acquisition	(170.1)
Proceeds from disposal of discontinued operations, net of cash	269.8	0.0
Intercompany loan investment, net	0.0	0.0
Investment in subsidiary	0.0	0.0
Restricted cash	21.1	0.4
Other	4.6	1.7
Net cash provided by (used in) investing activities	34.0	(53.0)
Cash Flows From Financing Activities:
Issuance of external debt	78.4	80.0
Repayment of external debt and capital leases	(151.5)	(63.5)
Debt financing costs	(0.1)	(0.4)
Excess tax benefit from share-based compensation	0.0	(20.2)
Proceeds from exercise of share options	6.3	20.6
Repurchase of shares	(501.6)	(12.3)
Intercompany loan borrowings, net	0.0	0.0
Capital contribution	0.0	0.0
Other	(30.0)	(4.0)
Net cash (used in) provided by financing activities	(598.5)	40.6
Effect of currency rate changes on cash	(0.1)	(7.4)
Net increase in cash and cash equivalents	(24.5)	345.7
Cash and cash equivalents at beginning of period	365.9	707.8
Cash and cash equivalents at end of period	341.4	1,053.5
Mallinckrodt plc
Cash Flows From Operating Activities:
Net cash provided by operating activities	42.9	120.7
Cash Flows From Investing Activities:
Capital expenditures	0.0	0.0
Cash paid with acquisition	0.0
Proceeds from disposal of discontinued operations, net of cash	0.0
Intercompany loan investment, net	0.0	(127.3)
Investment in subsidiary	0.0	0.0
Restricted cash	0.0	0.0
Other	0.0	0.0
Net cash provided by (used in) investing activities	0.0	(127.3)
Cash Flows From Financing Activities:
Issuance of external debt	0.0	0.0
Repayment of external debt and capital leases	0.0	0.0
Debt financing costs	0.0	0.0
Excess tax benefit from share-based compensation		0.0
Proceeds from exercise of share options	6.3	20.6
Repurchase of shares	(501.6)	(12.3)
Intercompany loan borrowings, net	452.4	0.0
Capital contribution	0.0	0.0
Other	0.0	0.0
Net cash (used in) provided by financing activities	(42.9)	8.3
Effect of currency rate changes on cash	0.0	0.0
Net increase in cash and cash equivalents	0.0	1.7
Cash and cash equivalents at beginning of period	0.1	0.3
Cash and cash equivalents at end of period	0.1	2.0
Mallinckrodt International Finance S.A.
Cash Flows From Operating Activities:
Net cash provided by operating activities	77.9	(78.3)
Cash Flows From Investing Activities:
Capital expenditures	0.0	0.0
Cash paid with acquisition	0.0
Proceeds from disposal of discontinued operations, net of cash	234.0
Intercompany loan investment, net	(16.0)	0.0
Investment in subsidiary	(176.2)	(124.9)
Restricted cash	0.0	0.0
Other	0.0	0.0
Net cash provided by (used in) investing activities	41.8	(124.9)
Cash Flows From Financing Activities:
Issuance of external debt	0.0	0.0
Repayment of external debt and capital leases	(133.9)	(8.2)
Debt financing costs	0.0	0.0
Excess tax benefit from share-based compensation		0.0
Proceeds from exercise of share options	0.0	0.0
Repurchase of shares	0.0	0.0
Intercompany loan borrowings, net	0.0	462.9
Capital contribution	0.0	0.0
Other	0.0	0.0
Net cash (used in) provided by financing activities	(133.9)	454.7
Effect of currency rate changes on cash	0.0	0.0
Net increase in cash and cash equivalents	(14.2)	251.5
Cash and cash equivalents at beginning of period	152.1	18.5
Cash and cash equivalents at end of period	137.9	270.0
Other Subsidiaries
Cash Flows From Operating Activities:
Net cash provided by operating activities	419.3	323.1
Cash Flows From Investing Activities:
Capital expenditures	(91.4)	(55.1)
Cash paid with acquisition	(170.1)
Proceeds from disposal of discontinued operations, net of cash	35.8
Intercompany loan investment, net	(436.4)	(335.6)
Investment in subsidiary	0.0	0.0
Restricted cash	21.1	0.4
Other	4.6	1.7
Net cash provided by (used in) investing activities	(636.4)	(388.6)
Cash Flows From Financing Activities:
Issuance of external debt	78.4	80.0
Repayment of external debt and capital leases	(17.6)	(55.3)
Debt financing costs	(0.1)	(0.4)
Excess tax benefit from share-based compensation		(20.2)
Proceeds from exercise of share options	0.0	0.0
Repurchase of shares	0.0	0.0
Intercompany loan borrowings, net	0.0	0.0
Capital contribution	176.2	124.9
Other	(30.0)	(4.0)
Net cash (used in) provided by financing activities	206.9	165.4
Effect of currency rate changes on cash	(0.1)	(7.4)
Net increase in cash and cash equivalents	(10.3)	92.5
Cash and cash equivalents at beginning of period	213.7	689.0
Cash and cash equivalents at end of period	203.4	781.5
Eliminations
Cash Flows From Operating Activities:
Net cash provided by operating activities	0.0	0.0
Cash Flows From Investing Activities:
Capital expenditures	0.0	0.0
Cash paid with acquisition	0.0
Proceeds from disposal of discontinued operations, net of cash	0.0
Intercompany loan investment, net	452.4	462.9
Investment in subsidiary	176.2	124.9
Restricted cash	0.0	0.0
Other	0.0	0.0
Net cash provided by (used in) investing activities	628.6	587.8
Cash Flows From Financing Activities:
Issuance of external debt	0.0	0.0
Repayment of external debt and capital leases	0.0	0.0
Debt financing costs	0.0	0.0
Excess tax benefit from share-based compensation		0.0
Proceeds from exercise of share options	0.0	0.0
Repurchase of shares	0.0	0.0
Intercompany loan borrowings, net	(452.4)	(462.9)
Capital contribution	(176.2)	(124.9)
Other	0.0	0.0
Net cash (used in) provided by financing activities	(628.6)	(587.8)
Effect of currency rate changes on cash	0.0	0.0
Net increase in cash and cash equivalents	0.0	0.0
Cash and cash equivalents at beginning of period	0.0	0.0
Cash and cash equivalents at end of period	$ 0.0	$ 0.0