Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 24, 2016	Jun. 30, 2017	Dec. 30, 2016	Dec. 25, 2015
Condensed Consolidating Financial Statements
Cash and Cash Equivalents and Restricted Cash		$ 541.2	$ 348.4	$ 361.1	$ 588.4
Restricted Cash and Investments, Current		0.3	0.0
Cash Flows From Operating Activities:
Net cash from operating activities	$ 222.5	683.0
Cash Flows From Investing Activities:
Capital expenditures	(101.6)	(84.5)
Acquisitions and intangibles, net of cash acquired	0.0	(169.5)
Proceeds from divestitures, net of cash	576.9	3.0
Cash paid with acquisition	0.0
Intercompany loan investment, net	0.0	0.0
Investment in subsidiary	0.0	0.0
Other	(9.9)	4.6
Net cash from investing activities	465.4	(246.4)
Cash Flows From Financing Activities:
Issuance of external debt	40.0	36.3
Repayment of external debt and capital leases	(332.8)	(177.5)
Debt financing costs	(13.0)	0.0
Proceeds from exercise of share options	3.9	4.9
Repurchase of shares	(380.8)	(326.6)
Intercompany loan borrowings, net	0.0	0.0
Payment of Subsidiary Dividend	0.0
Capital contribution	0.0	0.0
Other	(19.5)	(23.0)
Net cash from financing activities	(702.2)	(485.9)
Effect of currency rate changes on cash	1.6	2.1
Net change in cash, cash equivalents and restricted cash	(12.7)	(47.2)
Cash, cash equivalents and restricted cash at beginning of period	342.0
Cash and cash equivalents	342.0	521.9	330.2	342.0
Restricted Cash and Investments, Noncurrent		19.0	18.2
Mallinckrodt plc
Condensed Consolidating Financial Statements
Cash and Cash Equivalents and Restricted Cash		0.1	0.9	0.5	0.3
Restricted Cash and Investments, Current		0.0	0.0
Cash Flows From Operating Activities:
Net cash from operating activities	1,177.0	(4.3)
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	(801.7)	0.0
Investment in subsidiary	0.0	0.0
Other	0.0	0.0
Net cash from investing activities	(801.7)	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	3.9	4.9
Repurchase of shares	(380.8)	(326.6)
Intercompany loan borrowings, net	0.0	325.8
Payment of Subsidiary Dividend	0.0
Capital contribution	0.0	0.0
Other	2.0	0.0
Net cash from financing activities	(374.9)	4.1
Effect of currency rate changes on cash	0.0	0.0
Net change in cash, cash equivalents and restricted cash	0.4	(0.2)
Cash, cash equivalents and restricted cash at beginning of period	0.5
Cash and cash equivalents	0.5	0.1	0.9	0.5
Restricted Cash and Investments, Noncurrent		0.0	0.0
Mallinckrodt International Finance S.A.
Condensed Consolidating Financial Statements
Cash and Cash Equivalents and Restricted Cash		88.8	149.9	44.5	158.5
Restricted Cash and Investments, Current		0.0	0.0
Cash Flows From Operating Activities:
Net cash from operating activities	175.8	(72.9)
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	105.8
Investment in subsidiary	(307.9)	(461.7)
Other	0.0	0.0
Net cash from investing activities	(307.9)	(357.3)
Cash Flows From Financing Activities:
Issuance of external debt	0.0	0.0
Repayment of external debt and capital leases	(242.1)	(160.3)
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	1,662.1	520.8
Payment of Subsidiary Dividend	(1,170.0)
Capital contribution	0.0	0.0
Other	0.0	0.0
Net cash from financing activities	237.5	360.5
Effect of currency rate changes on cash	0.0	0.0
Net change in cash, cash equivalents and restricted cash	105.4	(69.7)
Cash, cash equivalents and restricted cash at beginning of period	44.5
Cash and cash equivalents	44.5	88.8	149.9	44.5
Restricted Cash and Investments, Noncurrent		0.0	0.0
Other Subsidiaries
Condensed Consolidating Financial Statements
Cash and Cash Equivalents and Restricted Cash		452.3	197.6	316.1	429.6
Restricted Cash and Investments, Current		0.3	0.0
Cash Flows From Operating Activities:
Net cash from operating activities	1,487.0	760.2
Cash Flows From Investing Activities:
Capital expenditures	(101.6)	(84.5)
Acquisitions and intangibles, net of cash acquired		(169.5)
Proceeds from divestitures, net of cash	576.9	4.4
Cash paid with acquisition	0.0
Intercompany loan investment, net	(860.4)	(952.4)
Investment in subsidiary	0.0	0.0
Other	(9.9)	4.6
Net cash from investing activities	(395.0)	(1,197.4)
Cash Flows From Financing Activities:
Issuance of external debt	40.0	36.3
Repayment of external debt and capital leases	(90.7)	(17.2)
Debt financing costs	(0.5)	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	0.0
Payment of Subsidiary Dividend	(1,447.3)
Capital contribution	307.9	461.7
Other	(21.5)	(23.0)
Net cash from financing activities	(1,212.1)	457.8
Effect of currency rate changes on cash	1.6	2.1
Net change in cash, cash equivalents and restricted cash	(118.5)	22.7
Cash, cash equivalents and restricted cash at beginning of period	297.0
Cash and cash equivalents	297.0	433.0	179.4	297.0
Restricted Cash and Investments, Noncurrent		19.0	18.2
Eliminations
Condensed Consolidating Financial Statements
Cash and Cash Equivalents and 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	(2,617.3)	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	1,662.1	846.6
Investment in subsidiary	307.9	461.7
Other	0.0	0.0
Net cash from investing activities	1,970.0	1,308.3
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
Proceeds from exercise of share options	0.0	0.0
Repurchase of shares	0.0	0.0
Intercompany loan borrowings, net	(1,662.1)	(846.6)
Payment of Subsidiary Dividend	2,617.3
Capital contribution	(307.9)	(461.7)
Other	0.0	0.0
Net cash from financing activities	647.3	(1,308.3)
Effect of currency rate changes on cash	0.0	0.0
Net change in cash, cash equivalents and restricted cash	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