Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 25, 2016	Mar. 31, 2017	Dec. 30, 2016	Dec. 25, 2015
Condensed Consolidating Financial Statements
Cash and Cash Equivalents, Including Restricted Cash		$ 386.6	$ 278.9	$ 361.1	$ 588.4
Restricted Cash and Investments, Current		26.2	0.0
Cash Flows From Operating Activities:
Net cash from operating activities	$ (97.4)	228.6
Cash Flows From Investing Activities:
Capital expenditures	(52.6)	(42.4)
Acquisitions and intangibles, net of cash acquired	0.0	(170.1)
Proceeds from divestitures, net of cash	576.9	5.8
Cash paid with acquisition	0.0
Intercompany loan investment, net	0.0	0.0
Investment in subsidiary	0.0	0.0
Other	(10.8)	3.9
Net cash from investing activities	513.5	(202.8)
Cash Flows From Financing Activities:
Issuance of external debt	25.0	16.4
Repayment of external debt and capital leases	(233.9)	(21.9)
Debt financing costs	(13.0)	0.0
Proceeds from exercise of share options	2.2	2.7
Repurchase of shares	(279.6)	(226.2)
Intercompany loan borrowings, net	0.0	0.0
Payment of Subsidiary Dividend	0.0
Capital contribution	0.0	0.0
Other	1.0	0.0
Net cash from financing activities	(498.3)	(229.0)
Effect of currency rate changes on cash	0.0	1.4
Cash, Cash Equivalents and Restricted Cash, Period Increase (Decrease)	(82.2)	(201.8)
Cash, cash equivalents and restricted cash at beginning of period	342.0
Cash and cash equivalents	342.0	341.4	259.8	342.0
Restricted Cash and Investments, Noncurrent		19.0	19.1
Mallinckrodt plc
Condensed Consolidating Financial Statements
Cash and Cash Equivalents, Including Restricted Cash		0.1	0.4	0.5	0.3
Restricted Cash and Investments, Current		0.0	0.0
Cash Flows From Operating Activities:
Net cash from operating activities	1,177.5	3.7
Cash Flows From Investing Activities:
Capital expenditures	0.0	0.0
Acquisitions and intangibles, net of cash acquired		0.0
Proceeds from divestitures, net of cash	0.0	0.0
Cash paid with acquisition	0.0
Intercompany loan investment, net	(900.9)	0.0
Investment in subsidiary	0.0	0.0
Other	0.0	0.0
Net cash from investing activities	(900.9)	0.0
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
Proceeds from exercise of share options	2.1	2.7
Repurchase of shares	(279.6)	(226.2)
Intercompany loan borrowings, net	0.0	219.6
Payment of Subsidiary Dividend	0.0
Capital contribution	0.0	0.0
Other	0.8	0.0
Net cash from financing activities	(276.7)	(3.9)
Effect of currency rate changes on cash	0.0	0.0
Cash, Cash Equivalents and Restricted Cash, Period Increase (Decrease)	(0.1)	(0.2)
Cash, cash equivalents and restricted cash at beginning of period	0.5
Cash and cash equivalents	0.5	0.1	0.4	0.5
Restricted Cash and Investments, Noncurrent		0.0	0.0
Mallinckrodt International Finance S.A.
Condensed Consolidating Financial Statements
Cash and Cash Equivalents, Including Restricted Cash		137.9	130.3	44.5	158.5
Restricted Cash and Investments, Current		0.0	0.0
Cash Flows From Operating Activities:
Net cash from operating activities	134.8	26.0
Cash Flows From Investing Activities:
Capital expenditures	0.0	0.0
Acquisitions and intangibles, net of cash acquired		0.0
Proceeds from divestitures, net of cash	0.0	(1.4)
Cash paid with acquisition	0.0
Intercompany loan investment, net	0.0	89.8
Investment in subsidiary	(307.9)	(130.0)
Other	0.0	0.0
Net cash from investing activities	(307.9)	(41.6)
Cash Flows From Financing Activities:
Issuance of external debt	0.0	0.0
Repayment of external debt and capital leases	(183.5)	(5.0)
Debt financing costs	(12.5)	0.0
Proceeds from exercise of share options	0.0	0.0
Repurchase of shares	0.0	0.0
Intercompany loan borrowings, net	1,624.9	0.0
Payment of Subsidiary Dividend	(1,170.0)
Capital contribution	0.0	0.0
Other	0.0	0.0
Net cash from financing activities	258.9	(5.0)
Effect of currency rate changes on cash	0.0	0.0
Cash, Cash Equivalents and Restricted Cash, Period Increase (Decrease)	85.8	(20.6)
Cash, cash equivalents and restricted cash at beginning of period	44.5
Cash and cash equivalents	44.5	137.9	130.3	44.5
Restricted Cash and Investments, Noncurrent		0.0	0.0
Other Subsidiaries
Condensed Consolidating Financial Statements
Cash and Cash Equivalents, Including Restricted Cash		248.6	148.2	316.1	429.6
Restricted Cash and Investments, Current		26.2	0.0
Cash Flows From Operating Activities:
Net cash from operating activities	1,062.6	198.9
Cash Flows From Investing Activities:
Capital expenditures	(52.6)	(42.4)
Acquisitions and intangibles, net of cash acquired		(170.1)
Proceeds from divestitures, net of cash	576.9	7.2
Cash paid with acquisition	0.0
Intercompany loan investment, net	(724.0)	(309.4)
Investment in subsidiary	0.0	0.0
Other	(10.8)	3.9
Net cash from investing activities	(210.5)	(510.8)
Cash Flows From Financing Activities:
Issuance of external debt	25.0	16.4
Repayment of external debt and capital leases	(50.4)	(16.9)
Debt financing costs	(0.5)	0.0
Proceeds from exercise of share options	0.1	0.0
Repurchase of shares	0.0	0.0
Intercompany loan borrowings, net	0.0	0.0
Payment of Subsidiary Dividend	(1,302.3)
Capital contribution	307.9	130.0
Other	0.2	0.0
Net cash from financing activities	(1,020.0)	129.5
Effect of currency rate changes on cash	0.0	1.4
Cash, Cash Equivalents and Restricted Cash, Period Increase (Decrease)	(167.9)	(181.0)
Cash, cash equivalents and restricted cash at beginning of period	297.0
Cash and cash equivalents	297.0	203.4	129.1	297.0
Restricted Cash and Investments, Noncurrent		19.0	19.1
Eliminations
Condensed Consolidating Financial Statements
Cash and Cash Equivalents, Including Restricted Cash		0.0	0.0	0.0	$ 0.0
Restricted Cash and Investments, Current		0.0	0.0
Cash Flows From Operating Activities:
Net cash from operating activities	(2,472.3)	0.0
Cash Flows From Investing Activities:
Capital expenditures	0.0	0.0
Acquisitions and intangibles, net of cash acquired		0.0
Proceeds from divestitures, net of cash	0.0	0.0
Cash paid with acquisition	0.0
Intercompany loan investment, net	1,624.9	219.6
Investment in subsidiary	307.9	130.0
Other	0.0	0.0
Net cash from investing activities	1,932.8	349.6
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
Proceeds from exercise of share options	0.0	0.0
Repurchase of shares	0.0	0.0
Intercompany loan borrowings, net	(1,624.9)	(219.6)
Payment of Subsidiary Dividend	2,472.3
Capital contribution	(307.9)	(130.0)
Other	0.0	0.0
Net cash from financing activities	539.5	(349.6)
Effect of currency rate changes on cash	0.0	0.0
Cash, Cash Equivalents and Restricted Cash, Period Increase (Decrease)	0.0	0.0
Cash, cash equivalents and restricted cash at beginning of period	0.0
Cash and cash equivalents	$ 0.0	0.0	0.0	$ 0.0
Restricted Cash and Investments, Noncurrent		$ 0.0	$ 0.0