Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 29, 2017	Sep. 30, 2016
Condensed Consolidating Financial Statements
Restricted Cash and Investments, Current	$ 0.0	$ 0.1
Cash Flows From Operating Activities:
Net cash from operating activities	448.5	873.2
Cash Flows From Investing Activities:
Capital expenditures	(151.3)	(133.9)
Acquisitions and intangibles, net of cash acquired	(35.9)	(245.4)
Proceeds from divestitures, net of cash	576.9	3.0
Intercompany loan investment, net	0.0	0.0
Investment in subsidiary	0.0	0.0
Proceeds from Divestiture of Subsidiary		0.0
Payments to Acquire Subsidiary		0.0
Other	0.5	5.3
Net cash from investing activities	390.2	(371.0)
Cash Flows From Financing Activities:
Issuance of external debt	540.0	36.3
Repayment of external debt and capital leases	(887.5)	(439.0)
Debt financing costs	(12.7)	0.0
Proceeds from exercise of share options	4.0	10.4
Repurchase of shares	(437.7)	(377.5)
Intercompany loan borrowings, net	0.0	0.0
Payment of Subsidiary Dividend	0.0
Capital contribution	0.0	0.0
Other	(18.6)	(23.0)
Net cash from financing activities	(812.5)	(792.8)
Effect of currency rate changes on cash	2.7	1.8
Net change in cash, cash equivalents and restricted cash	28.9	(288.8)
Cash and cash equivalents, end of period	371.8	280.5
Restricted Cash and Investments, Noncurrent	18.2	19.0
Cash and Cash Equivalents and Restricted Cash	361.1	588.4
Cash and Cash Equivalents, Including Restricted Cash, Period End	390.0	299.6
Mallinckrodt plc
Condensed Consolidating Financial Statements
Restricted Cash and Investments, Current	0.0	0.0
Cash Flows From Operating Activities:
Net cash from operating activities	1,172.0	(21.3)
Cash Flows From Investing Activities:
Capital expenditures	0.0	0.0
Acquisitions and intangibles, net of cash acquired	0.0	0.0
Proceeds from divestitures, net of cash	0.0	0.0
Intercompany loan investment, net	(741.3)	0.0
Investment in subsidiary	0.0	0.0
Proceeds from Divestiture of Subsidiary		3.4
Payments to Acquire Subsidiary		0.0
Other	0.0	0.0
Net cash from investing activities	(741.3)	3.4
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	4.0	10.4
Repurchase of shares	(437.7)	(377.5)
Intercompany loan borrowings, net	0.0	385.0
Payment of Subsidiary Dividend	0.0
Capital contribution	0.0	0.0
Other	3.2	0.0
Net cash from financing activities	(430.5)	17.9
Effect of currency rate changes on cash	0.0	0.0
Net change in cash, cash equivalents and restricted cash	0.2	0.0
Cash and cash equivalents, end of period	0.7	0.3
Restricted Cash and Investments, Noncurrent	0.0	0.0
Cash and Cash Equivalents and Restricted Cash	0.5	0.3
Cash and Cash Equivalents, Including Restricted Cash, Period End	0.7	0.3
Mallinckrodt International Finance S.A.
Condensed Consolidating Financial Statements
Restricted Cash and Investments, Current	0.0	0.0
Cash Flows From Operating Activities:
Net cash from operating activities	1,233.7	(99.3)
Cash Flows From Investing Activities:
Capital expenditures	0.0	0.0
Acquisitions and intangibles, net of cash acquired	0.0	0.0
Proceeds from divestitures, net of cash	0.0	(1.4)
Intercompany loan investment, net	0.0	(69.4)
Investment in subsidiary	(1,412.5)	(815.0)
Proceeds from Divestiture of Subsidiary		0.0
Payments to Acquire Subsidiary		0.0
Other	0.0	0.0
Net cash from investing activities	(1,412.5)	(885.8)
Cash Flows From Financing Activities:
Issuance of external debt	500.0	0.0
Repayment of external debt and capital leases	(759.9)	(420.3)
Debt financing costs	(12.7)	0.0
Proceeds from exercise of share options	0.0	0.0
Repurchase of shares	0.0	0.0
Intercompany loan borrowings, net	1,614.5	1,271.9
Payment of Subsidiary Dividend	(1,170.0)
Capital contribution	0.0	0.0
Other	0.0	0.0
Net cash from financing activities	171.9	851.6
Effect of currency rate changes on cash	0.0	0.0
Net change in cash, cash equivalents and restricted cash	(6.9)	(133.5)
Cash and cash equivalents, end of period	37.6	25.0
Restricted Cash and Investments, Noncurrent	0.0	0.0
Cash and Cash Equivalents and Restricted Cash	44.5	158.5
Cash and Cash Equivalents, Including Restricted Cash, Period End	37.6	25.0
Other Subsidiaries
Condensed Consolidating Financial Statements
Restricted Cash and Investments, Current	0.0	0.1
Cash Flows From Operating Activities:
Net cash from operating activities	1,963.0	993.8
Cash Flows From Investing Activities:
Capital expenditures	(151.3)	(133.9)
Acquisitions and intangibles, net of cash acquired	(35.9)	(245.4)
Proceeds from divestitures, net of cash	576.9	4.4
Intercompany loan investment, net	(920.8)	(1,587.5)
Investment in subsidiary	0.0	0.0
Proceeds from Divestiture of Subsidiary		0.0
Payments to Acquire Subsidiary		(3.4)
Other	0.5	5.3
Net cash from investing activities	(530.6)	(1,960.5)
Cash Flows From Financing Activities:
Issuance of external debt	40.0	36.3
Repayment of external debt and capital leases	(127.6)	(18.7)
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	47.6	0.0
Payment of Subsidiary Dividend	(2,750.2)
Capital contribution	1,412.5	815.0
Other	(21.8)	(23.0)
Net cash from financing activities	(1,399.5)	809.6
Effect of currency rate changes on cash	2.7	1.8
Net change in cash, cash equivalents and restricted cash	35.6	(155.3)
Cash and cash equivalents, end of period	333.5	255.2
Restricted Cash and Investments, Noncurrent	18.2	19.0
Cash and Cash Equivalents and Restricted Cash	316.1	429.6
Cash and Cash Equivalents, Including Restricted Cash, Period End	351.7	274.3
Eliminations
Condensed Consolidating Financial Statements
Restricted Cash and Investments, Current	0.0	0.0
Cash Flows From Operating Activities:
Net cash from operating activities	(3,920.2)	0.0
Cash Flows From Investing Activities:
Capital expenditures	0.0	0.0
Acquisitions and intangibles, net of cash acquired	0.0	0.0
Proceeds from divestitures, net of cash	0.0	0.0
Intercompany loan investment, net	1,662.1	1,656.9
Investment in subsidiary	1,412.5	815.0
Proceeds from Divestiture of Subsidiary		(3.4)
Payments to Acquire Subsidiary		3.4
Other	0.0	0.0
Net cash from investing activities	3,074.6	2,471.9
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)	(1,656.9)
Payment of Subsidiary Dividend	3,920.2
Capital contribution	(1,412.5)	(815.0)
Other	0.0	0.0
Net cash from financing activities	845.6	(2,471.9)
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 and cash equivalents, end of period	0.0	0.0
Restricted Cash and Investments, Noncurrent	0.0	0.0
Cash and Cash Equivalents and Restricted Cash	0.0	0.0
Cash and Cash Equivalents, Including Restricted Cash, Period End	$ 0.0	$ 0.0