Condensed Consolidating and Combining Financial Statements (Schedule of Condensed Consolidating and Combining Statements of Cash Flows) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 25, 2015	Sep. 26, 2014	Sep. 27, 2013
Cash Flows From Operating Activities:
Net cash (used in) provided by operating activities	$ 896.4	$ 373.4	$ 135.9
Cash Flows From Investing Activities:
Capital expenditures	(148.0)	(127.8)	(147.9)
Acquisitions and intangibles, net of cash acquired	(2,154.7)	(2,793.8)	(88.1)
Intercompany Loan Investment	0.0	0.0	0.0
Subsidiary dividend proceeds		0.0
Investment in subsidiary	0.0	0.0	0.0
Restricted cash	3.1	4.1	0.0
Other	3.0	26.7	1.3
Net cash used in investing activities	(2,296.6)	(2,890.8)	(234.7)
Cash Flows From Financing Activities:
Issuance of external debt	3,010.0	3,043.2	898.1
Repayment of capital leases	(1,848.4)	(34.8)	(1.3)
Excess tax benefit from share-based compensation	34.1	8.9	3.4
Debt financing costs	(39.9)	(71.7)	(12.0)
Net transfers to parent	0.0	0.0	(515.9)
Proceeds from exercise of share options	34.4	25.8	0.6
Subsidiary dividend payment		0.0
Intercompany loan borrowings	0.0	0.0	0.0
Capital contribution	0.0	0.0	0.0
Repurchase of ordinary shares, value	(92.2)	(17.5)
Other	(28.1)	0.0	0.1
Net cash provided by financing activities	1,069.9	2,953.9	373.0
Effect of currency rate changes on cash	(11.6)	(4.2)	1.3
Net (decrease) increase in cash and cash equivalents	(341.9)	432.3	275.5
Cash and cash equivalents at beginning of period	707.8	275.5	0.0
Cash and cash equivalents at end of period	365.9	707.8	275.5
Mallinckrodt plc
Cash Flows From Operating Activities:
Net cash (used in) provided by operating activities	207.0	18.2	(1.8)
Cash Flows From Investing Activities:
Capital expenditures	0.0	0.0	0.0
Acquisitions and intangibles, net of cash acquired	0.0	0.0	0.0
Intercompany Loan Investment	(149.4)	(25.0)	0.0
Subsidiary dividend proceeds		0.0
Investment in subsidiary	0.0	0.0	0.0
Restricted cash	0.0	0.0
Other	0.0	0.0	0.0
Net cash used in investing activities	(149.4)	(25.0)	0.0
Cash Flows From Financing Activities:
Issuance of external debt	0.0	0.0	0.0
Repayment of capital leases	0.0	0.0	0.0
Excess tax benefit from share-based compensation	0.0	0.0	0.0
Debt financing costs	0.0	0.0	0.0
Net transfers to parent			0.0
Proceeds from exercise of share options	34.4	25.8	0.6
Subsidiary dividend payment		0.0
Intercompany loan borrowings	0.0	(2.4)	2.4
Capital contribution	0.0	0.0	0.0
Repurchase of ordinary shares, value	(92.2)	(17.5)
Other	0.0	0.0	0.0
Net cash provided by financing activities	(57.8)	5.9	3.0
Effect of currency rate changes on cash	0.0	0.0	0.0
Net (decrease) increase in cash and cash equivalents	(0.2)	(0.9)	1.2
Cash and cash equivalents at beginning of period	0.3	1.2	0.0
Cash and cash equivalents at end of period	0.1	0.3	1.2
Mallinckrodt International Finance S.A.
Cash Flows From Operating Activities:
Net cash (used in) provided by operating activities	(148.2)	(65.0)	(8.4)
Cash Flows From Investing Activities:
Capital expenditures	0.0	0.0	0.0
Acquisitions and intangibles, net of cash acquired	0.0	0.0	0.0
Intercompany Loan Investment	0.0	(298.1)	(2.4)
Subsidiary dividend proceeds		300.5
Investment in subsidiary	(3,014.4)	(3,735.5)	(68.0)
Restricted cash	0.0	0.0
Other	0.0	0.0	0.0
Net cash used in investing activities	(3,014.4)	(3,733.1)	(70.4)
Cash Flows From Financing Activities:
Issuance of external debt	2,890.0	2,893.3	898.1
Repayment of capital leases	(258.3)	(3.3)	0.0
Excess tax benefit from share-based compensation	0.0	0.0	0.0
Debt financing costs	(39.1)	(70.7)	(12.0)
Net transfers to parent			(1,160.4)
Proceeds from exercise of share options	0.0	0.0	0.0
Subsidiary dividend payment		0.0
Intercompany loan borrowings	703.6	940.8	409.6
Capital contribution	0.0	0.0	0.0
Repurchase of ordinary shares, value	0.0	0.0
Other	0.0	0.0	0.0
Net cash provided by financing activities	3,296.2	3,760.1	135.3
Effect of currency rate changes on cash	0.0	0.0	0.0
Net (decrease) increase in cash and cash equivalents	133.6	(38.0)	56.5
Cash and cash equivalents at beginning of period	18.5	56.5	0.0
Cash and cash equivalents at end of period	152.1	18.5	56.5
Other Subsidiaries
Cash Flows From Operating Activities:
Net cash (used in) provided by operating activities	837.6	420.2	146.1
Cash Flows From Investing Activities:
Capital expenditures	(148.0)	(127.8)	(147.9)
Acquisitions and intangibles, net of cash acquired	(2,154.7)	(2,793.8)	(88.1)
Intercompany Loan Investment	(554.2)	(915.8)	(409.6)
Subsidiary dividend proceeds		0.0
Investment in subsidiary	0.0	0.0	0.0
Restricted cash	3.1	4.1
Other	3.0	26.7	1.3
Net cash used in investing activities	(2,850.8)	(3,806.6)	(644.3)
Cash Flows From Financing Activities:
Issuance of external debt	120.0	149.9	0.0
Repayment of capital leases	(1,590.1)	(31.5)	(1.3)
Excess tax benefit from share-based compensation	34.1	8.9	3.4
Debt financing costs	(0.8)	(1.0)	0.0
Net transfers to parent			644.5
Proceeds from exercise of share options	0.0	0.0	0.0
Subsidiary dividend payment		(300.5)
Intercompany loan borrowings	0.0	300.5	0.0
Capital contribution	3,014.4	3,735.5	68.0
Repurchase of ordinary shares, value	0.0	0.0
Other	(28.1)	0.0	0.1
Net cash provided by financing activities	1,549.5	3,861.8	714.7
Effect of currency rate changes on cash	(11.6)	(4.2)	1.3
Net (decrease) increase in cash and cash equivalents	(475.3)	471.2	217.8
Cash and cash equivalents at beginning of period	689.0	217.8	0.0
Cash and cash equivalents at end of period	213.7	689.0	217.8
Eliminations
Cash Flows From Operating Activities:
Net cash (used in) provided by operating activities	0.0	0.0	0.0
Cash Flows From Investing Activities:
Capital expenditures	0.0	0.0	0.0
Acquisitions and intangibles, net of cash acquired	0.0	0.0	0.0
Intercompany Loan Investment	703.6	1,238.9	412.0
Subsidiary dividend proceeds		(300.5)
Investment in subsidiary	3,014.4	3,735.5	68.0
Restricted cash	0.0	0.0
Other	0.0	0.0	0.0
Net cash used in investing activities	3,718.0	4,673.9	480.0
Cash Flows From Financing Activities:
Issuance of external debt	0.0	0.0	0.0
Repayment of capital leases	0.0	0.0	0.0
Excess tax benefit from share-based compensation	0.0	0.0	0.0
Debt financing costs	0.0	0.0	0.0
Net transfers to parent			0.0
Proceeds from exercise of share options	0.0	0.0	0.0
Subsidiary dividend payment		300.5
Intercompany loan borrowings	(703.6)	(1,238.9)	(412.0)
Capital contribution	(3,014.4)	(3,735.5)	(68.0)
Repurchase of ordinary shares, value	0.0	0.0
Other	0.0	0.0	0.0
Net cash provided by financing activities	(3,718.0)	(4,673.9)	(480.0)
Effect of currency rate changes on cash	0.0	0.0	0.0
Net (decrease) increase in cash and cash equivalents	0.0	0.0	0.0
Cash and cash equivalents at beginning of period	0.0	0.0	0.0
Cash and cash equivalents at end of period	$ 0.0	$ 0.0	$ 0.0