Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 25, 2015	Dec. 26, 2014
Cash Flows From Operating Activities:
Net cash provided by operating activities	$ 311.4	$ 216.8
Cash Flows From Investing Activities:
Capital expenditures	(49.0)	(22.3)
Proceeds from disposal of discontinued operations, net of cash	264.0	0.0
Intercompany loan investment, net	0.0	0.0
Investment in subsidiary	0.0	0.0
Restricted cash	(0.1)	0.4
Other	0.7	1.0
Net cash provided by (used in) investing activities	215.6	(20.9)
Cash Flows From Financing Activities:
Issuance of external debt	62.0	0.0
Repayment of external debt and capital leases	(129.6)	(7.8)
Debt financing costs	(0.1)	0.0
Excess tax benefit from share-based compensation	0.0	8.9
Proceeds from exercise of share options	3.6	8.7
Repurchase of shares	(275.4)	(10.6)
Intercompany loan borrowings, net	0.0	0.0
Capital contribution	0.0	0.0
Other	(30.0)	0.0
Net cash (used in) provided by financing activities	(369.5)	(0.8)
Effect of currency rate changes on cash	(1.5)	(3.9)
Net increase in cash and cash equivalents	156.0	191.2
Cash and cash equivalents at beginning of period	365.9	707.8
Cash and cash equivalents at end of period	521.9	899.0
Mallinckrodt plc
Cash Flows From Operating Activities:
Net cash provided by operating activities	39.2	14.7
Cash Flows From Investing Activities:
Capital expenditures	0.0	0.0
Proceeds from disposal of discontinued operations, net of cash	0.0
Intercompany loan investment, net	0.0	(11.9)
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	(11.9)
Cash Flows From Financing Activities:
Issuance of external debt	0.0
Repayment of external debt and capital leases	0.0	0.0
Debt financing costs	0.0
Excess tax benefit from share-based compensation		0.0
Proceeds from exercise of share options	3.6	8.7
Repurchase of shares	(275.4)	(10.6)
Intercompany loan borrowings, net	232.8	0.0
Capital contribution	0.0	0.0
Other	0.0
Net cash (used in) provided by financing activities	(39.0)	(1.9)
Effect of currency rate changes on cash	0.0	0.0
Net increase in cash and cash equivalents	0.2	0.9
Cash and cash equivalents at beginning of period	0.1	0.3
Cash and cash equivalents at end of period	0.3	1.2
Mallinckrodt International Finance S.A.
Cash Flows From Operating Activities:
Net cash provided by operating activities	51.9	(38.3)
Cash Flows From Investing Activities:
Capital expenditures	0.0	0.0
Proceeds from disposal of discontinued operations, net of cash	235.4
Intercompany loan investment, net	(105.8)	0.0
Investment in subsidiary	(46.2)	(20.0)
Restricted cash	0.0	0.0
Other	0.0	0.0
Net cash provided by (used in) investing activities	83.4	(20.0)
Cash Flows From Financing Activities:
Issuance of external debt	0.0
Repayment of external debt and capital leases	(128.9)	(3.3)
Debt financing costs	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	182.5
Capital contribution	0.0	0.0
Other	0.0
Net cash (used in) provided by financing activities	(128.9)	179.2
Effect of currency rate changes on cash	0.0	0.0
Net increase in cash and cash equivalents	6.4	120.9
Cash and cash equivalents at beginning of period	152.1	18.5
Cash and cash equivalents at end of period	158.5	139.4
Other Subsidiaries
Cash Flows From Operating Activities:
Net cash provided by operating activities	220.3	240.4
Cash Flows From Investing Activities:
Capital expenditures	(49.0)	(22.3)
Proceeds from disposal of discontinued operations, net of cash	28.6
Intercompany loan investment, net	(127.0)	(170.6)
Investment in subsidiary	0.0	0.0
Restricted cash	(0.1)	0.4
Other	0.7	1.0
Net cash provided by (used in) investing activities	(146.8)	(191.5)
Cash Flows From Financing Activities:
Issuance of external debt	62.0
Repayment of external debt and capital leases	(0.7)	(4.5)
Debt financing costs	(0.1)
Excess tax benefit from share-based compensation		8.9
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	46.2	20.0
Other	(30.0)
Net cash (used in) provided by financing activities	77.4	24.4
Effect of currency rate changes on cash	(1.5)	(3.9)
Net increase in cash and cash equivalents	149.4	69.4
Cash and cash equivalents at beginning of period	213.7	689.0
Cash and cash equivalents at end of period	363.1	758.4
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
Proceeds from disposal of discontinued operations, net of cash	0.0
Intercompany loan investment, net	232.8	182.5
Investment in subsidiary	46.2	20.0
Restricted cash	0.0	0.0
Other	0.0	0.0
Net cash provided by (used in) investing activities	279.0	202.5
Cash Flows From Financing Activities:
Issuance of external debt	0.0
Repayment of external debt and capital leases	0.0	0.0
Debt financing costs	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	(232.8)	(182.5)
Capital contribution	(46.2)	(20.0)
Other	0.0
Net cash (used in) provided by financing activities	(279.0)	(202.5)
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
Contrast Media and Delivery Systems
Cash Flows From Investing Activities:
Proceeds from disposal of discontinued operations, net of cash	$ 264.0