Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Millions	Jun. 29, 2018	Dec. 29, 2017	Jun. 30, 2017
Current Assets:
Cash and cash equivalents	$ 235.7	$ 1,260.9	$ 330.2
Accounts receivable, net	337.6	275.4
Inventories	184.4	128.7
Prepaid expenses and other current assets	135.6	74.7
Notes receivable	0.0	154.0
Current assets held for sale	1,112.5	391.5
Intercompany receivables	0.0	0.0
Total current assets	2,005.8	2,285.2
Property, plant and equipment, net	430.1	413.2
Goodwill	3,676.7	3,482.7
Intangible assets, net	8,769.0	8,261.0
Disposal Group, Including Discontinued Operation, Assets, Noncurrent	0.0	742.7
Investment in subsidiaries	0.0	0.0
Intercompany loans receivable	0.0	0.0
Other assets	168.2	156.2
Total Assets	15,049.8	15,341.0
Current Liabilities:
Current maturities of long-term debt	22.2	313.7
Accounts payable	75.8	77.3
Accrued payroll and payroll-related costs	74.6	78.4
Accrued interest	60.4	57.0
Income taxes payable	39.9	15.5
Accrued and other current liabilities	441.0	368.5
Current liabilities held for sale	170.6	140.0
Intercompany payables	0.0	0.0
Total current liabilities	884.5	1,050.4
Long-term debt	6,335.1	6,420.9
Pension and postretirement benefits	65.3	67.1
Environmental liabilities	62.2	62.8
Deferred income taxes	809.7	749.1
Other income tax liabilities	129.2	94.1
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent	0.0	22.6
Intercompany loans payable	0.0	0.0
Other liabilities	289.4	352.0
Total Liabilities	8,575.4	8,819.0
Shareholders' Equity	6,474.4	6,522.0
Total Liabilities and Shareholders' Equity	15,049.8	15,341.0
Mallinckrodt plc
Current Assets:
Cash and cash equivalents	0.6	0.7	0.9
Accounts receivable, net	0.0	0.0
Inventories	0.0	0.0
Prepaid expenses and other current assets	0.3	1.0
Notes receivable	0.0	0.0
Current assets held for sale	0.0	0.0
Intercompany receivables	123.0	70.0
Total current assets	123.9	71.7
Property, plant and equipment, net	0.0	0.0
Goodwill	0.0	0.0
Intangible assets, net	0.0	0.0
Disposal Group, Including Discontinued Operation, Assets, Noncurrent		0.0
Investment in subsidiaries	6,063.6	6,551.6
Intercompany loans receivable	505.4	593.1
Other assets	0.0	0.0
Total Assets	6,692.9	7,216.4
Current Liabilities:
Current maturities of long-term debt	0.0	0.0
Accounts payable	0.2	0.1
Accrued payroll and payroll-related costs	0.0	0.0
Accrued interest	0.0	0.0
Income taxes payable	0.0	0.0
Accrued and other current liabilities	0.8	0.8
Current liabilities held for sale	0.0	0.0
Intercompany payables	217.5	693.5
Total current liabilities	218.5	694.4
Long-term debt	0.0	0.0
Pension and postretirement benefits	0.0	0.0
Environmental liabilities	0.0	0.0
Deferred income taxes	0.0	0.0
Other income tax liabilities	0.0	0.0
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent		0.0
Intercompany loans payable	0.0	0.0
Other liabilities	0.0	0.0
Total Liabilities	218.5	694.4
Shareholders' Equity	6,474.4	6,522.0
Total Liabilities and Shareholders' Equity	6,692.9	7,216.4
Mallinckrodt International Finance S.A.
Current Assets:
Cash and cash equivalents	21.3	908.8	149.9
Accounts receivable, net	0.0	0.0
Inventories	0.0	0.0
Prepaid expenses and other current assets	0.4	0.2
Notes receivable	0.0	0.0
Current assets held for sale	0.0	0.0
Intercompany receivables	26.4	173.4
Total current assets	48.1	1,082.4
Property, plant and equipment, net	0.0	0.0
Goodwill	0.0	0.0
Intangible assets, net	0.0	0.0
Disposal Group, Including Discontinued Operation, Assets, Noncurrent		0.0
Investment in subsidiaries	23,666.7	23,217.8
Intercompany loans receivable	0.0	0.0
Other assets	0.0	0.0
Total Assets	23,714.8	24,300.2
Current Liabilities:
Current maturities of long-term debt	22.0	313.5
Accounts payable	0.0	0.0
Accrued payroll and payroll-related costs	0.0	0.0
Accrued interest	54.7	53.0
Income taxes payable	0.0	0.0
Accrued and other current liabilities	0.4	0.4
Current liabilities held for sale	0.0	0.0
Intercompany payables	19.4	104.6
Total current liabilities	96.5	471.5
Long-term debt	6,079.3	6,206.8
Pension and postretirement benefits	0.0	0.0
Environmental liabilities	0.0	0.0
Deferred income taxes	0.0	0.0
Other income tax liabilities	0.0	0.0
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent		0.0
Intercompany loans payable	5,791.9	5,257.9
Other liabilities	7.8	7.8
Total Liabilities	11,975.5	11,944.0
Shareholders' Equity	11,739.3	12,356.2
Total Liabilities and Shareholders' Equity	23,714.8	24,300.2
Other Subsidiaries
Current Assets:
Cash and cash equivalents	213.8	351.4	179.4
Accounts receivable, net	337.6	275.4
Inventories	184.4	128.7
Prepaid expenses and other current assets	134.9	73.5
Notes receivable	0.0	154.0
Current assets held for sale	1,112.5	391.5
Intercompany receivables	277.8	831.4
Total current assets	2,261.0	2,205.9
Property, plant and equipment, net	430.1	413.2
Goodwill	3,676.7	3,482.7
Intangible assets, net	8,769.0	8,261.0
Disposal Group, Including Discontinued Operation, Assets, Noncurrent		742.7
Investment in subsidiaries	11,739.3	12,356.2
Intercompany loans receivable	5,286.5	4,664.8
Other assets	168.2	156.2
Total Assets	32,330.8	32,282.7
Current Liabilities:
Current maturities of long-term debt	0.2	0.2
Accounts payable	75.6	77.2
Accrued payroll and payroll-related costs	74.6	78.4
Accrued interest	5.7	4.0
Income taxes payable	39.9	15.5
Accrued and other current liabilities	439.8	367.3
Current liabilities held for sale	170.6	140.0
Intercompany payables	190.3	276.7
Total current liabilities	996.7	959.3
Long-term debt	255.8	214.1
Pension and postretirement benefits	65.3	67.1
Environmental liabilities	62.2	62.8
Deferred income taxes	809.7	749.1
Other income tax liabilities	129.2	94.1
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent		22.6
Intercompany loans payable	0.0	0.0
Other liabilities	281.6	344.2
Total Liabilities	2,600.5	2,513.3
Shareholders' Equity	29,730.3	29,769.4
Total Liabilities and Shareholders' Equity	32,330.8	32,282.7
Eliminations
Current Assets:
Cash and cash equivalents	0.0	0.0	$ 0.0
Accounts receivable, net	0.0	0.0
Inventories	0.0	0.0
Prepaid expenses and other current assets	0.0	0.0
Notes receivable	0.0	0.0
Current assets held for sale	0.0	0.0
Intercompany receivables	(427.2)	(1,074.8)
Total current assets	(427.2)	(1,074.8)
Property, plant and equipment, net	0.0	0.0
Goodwill	0.0	0.0
Intangible assets, net	0.0	0.0
Disposal Group, Including Discontinued Operation, Assets, Noncurrent		0.0
Investment in subsidiaries	(41,469.6)	(42,125.6)
Intercompany loans receivable	(5,791.9)	(5,257.9)
Other assets	0.0	0.0
Total Assets	(47,688.7)	(48,458.3)
Current Liabilities:
Current maturities of long-term debt	0.0	0.0
Accounts payable	0.0	0.0
Accrued payroll and payroll-related costs	0.0	0.0
Accrued interest	0.0	0.0
Income taxes payable	0.0	0.0
Accrued and other current liabilities	0.0	0.0
Current liabilities held for sale	0.0	0.0
Intercompany payables	(427.2)	(1,074.8)
Total current liabilities	(427.2)	(1,074.8)
Long-term debt	0.0	0.0
Pension and postretirement benefits	0.0	0.0
Environmental liabilities	0.0	0.0
Deferred income taxes	0.0	0.0
Other income tax liabilities	0.0	0.0
Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent		0.0
Intercompany loans payable	(5,791.9)	(5,257.9)
Other liabilities	0.0	0.0
Total Liabilities	(6,219.1)	(6,332.7)
Shareholders' Equity	(41,469.6)	(42,125.6)
Total Liabilities and Shareholders' Equity	(47,688.7)	(48,458.3)
Ordinary A
Condensed Consolidating Financial Statements
Ordinary A shares	$ 0.0	$ 0.0