Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Millions	Mar. 29, 2019	Dec. 28, 2018	Mar. 30, 2018	Dec. 29, 2017
Current Assets:
Cash and cash equivalents	$ 225.8	$ 348.9	$ 511.9
Accounts receivable, net	575.9	623.3
Inventories	319.7	322.3
Prepaid expenses and other current assets	120.1	132.7
Intercompany receivables	0.0	0.0
Total current assets	1,241.5	1,427.2
Property, plant and equipment, net	977.0	982.0
Intangible assets, net	8,060.2	8,282.8
Investment in subsidiaries	0.0	0.0
Intercompany loans receivable	0.0	0.0
Other assets	276.8	185.3
Total Assets	10,555.5	10,877.3
Current Liabilities:
Current maturities of long-term debt	19.8	22.4
Accounts payable	132.6	147.5
Accrued payroll and payroll-related costs	60.8	124.0
Accrued interest	72.4	77.6
Income taxes payable	7.7	25.0
Accrued and other current liabilities	560.7	547.2
Intercompany payables	0.0	0.0
Total current liabilities	854.0	943.7
Long-term debt	5,817.6	6,069.2
Pension and postretirement benefits	59.7	60.5
Environmental liabilities	59.6	59.7
Deferred income taxes	81.1	324.3
Other income tax liabilities	262.8	228.0
Intercompany loans payable	0.0	0.0
Other liabilities	366.8	304.6
Total Liabilities	7,501.6	7,990.0
Shareholders' Equity	3,053.9	2,887.3	6,461.3	$ 6,522.0
Total Liabilities and Shareholders' Equity	10,555.5	10,877.3
Mallinckrodt plc
Current Assets:
Cash and cash equivalents	0.5	0.4	1.4
Accounts receivable, net	0.0	0.0
Inventories	0.0	0.0
Prepaid expenses and other current assets	2.1	3.9
Intercompany receivables	140.5	131.1
Total current assets	143.1	135.4
Property, plant and equipment, net	0.0	0.0
Intangible assets, net	0.0	0.0
Investment in subsidiaries	2,652.3	2,481.6
Intercompany loans receivable	469.1	497.7
Other assets	0.0	0.0
Total Assets	3,264.5	3,114.7
Current Liabilities:
Current maturities of long-term debt	0.0	0.0
Accounts payable	0.1	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	0.6	0.6
Intercompany payables	209.9	226.7
Total current liabilities	210.6	227.4
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
Intercompany loans payable	0.0	0.0
Other liabilities	0.0	0.0
Total Liabilities	210.6	227.4
Shareholders' Equity	3,053.9	2,887.3
Total Liabilities and Shareholders' Equity	3,264.5	3,114.7
Mallinckrodt International Finance S.A.
Current Assets:
Cash and cash equivalents	27.2	140.8	212.8
Accounts receivable, net	0.0	0.0
Inventories	0.0	0.0
Prepaid expenses and other current assets	0.0	0.2
Intercompany receivables	29.2	29.2
Total current assets	56.4	170.2
Property, plant and equipment, net	0.0	0.0
Intangible assets, net	0.0	0.0
Investment in subsidiaries	12,978.3	25,506.1
Intercompany loans receivable	0.0	0.0
Other assets	0.0	0.0
Total Assets	13,034.7	25,676.3
Current Liabilities:
Current maturities of long-term debt	0.0	22.1
Accounts payable	0.0	0.0
Accrued payroll and payroll-related costs	0.0	0.0
Accrued interest	20.3	48.7
Income taxes payable	0.0	0.0
Accrued and other current liabilities	0.2	0.4
Intercompany payables	5,668.6	827.8
Total current liabilities	5,689.1	899.0
Long-term debt	487.0	3,566.9
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
Intercompany loans payable	3,037.1	12,840.7
Other liabilities	8.0	7.6
Total Liabilities	9,221.2	17,314.2
Shareholders' Equity	3,813.5	8,362.1
Total Liabilities and Shareholders' Equity	13,034.7	25,676.3
Other Subsidiaries
Current Assets:
Cash and cash equivalents	198.1	207.7	297.7
Accounts receivable, net	575.9	623.3
Inventories	319.7	322.3
Prepaid expenses and other current assets	118.0	128.6
Intercompany receivables	5,925.8	1,087.9
Total current assets	7,137.5	2,369.8
Property, plant and equipment, net	977.0	982.0
Intangible assets, net	8,060.2	8,282.8
Investment in subsidiaries	3,813.5	8,362.1
Intercompany loans receivable	2,568.0	12,343.0
Other assets	276.8	185.3
Total Assets	22,833.0	32,525.0
Current Liabilities:
Current maturities of long-term debt	19.8	0.3
Accounts payable	132.5	147.4
Accrued payroll and payroll-related costs	60.8	124.0
Accrued interest	52.1	28.9
Income taxes payable	7.7	25.0
Accrued and other current liabilities	559.9	546.2
Intercompany payables	217.0	193.7
Total current liabilities	1,049.8	1,065.5
Long-term debt	5,330.6	2,502.3
Pension and postretirement benefits	59.7	60.5
Environmental liabilities	59.6	59.7
Deferred income taxes	81.1	324.3
Other income tax liabilities	262.8	228.0
Intercompany loans payable	0.0	0.0
Other liabilities	358.8	297.0
Total Liabilities	7,202.4	4,537.3
Shareholders' Equity	15,630.6	27,987.7
Total Liabilities and Shareholders' Equity	22,833.0	32,525.0
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
Intercompany receivables	(6,095.5)	(1,248.2)
Total current assets	(6,095.5)	(1,248.2)
Property, plant and equipment, net	0.0	0.0
Intangible assets, net	0.0	0.0
Investment in subsidiaries	(19,444.1)	(36,349.8)
Intercompany loans receivable	(3,037.1)	(12,840.7)
Other assets	0.0	0.0
Total Assets	(28,576.7)	(50,438.7)
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
Intercompany payables	(6,095.5)	(1,248.2)
Total current liabilities	(6,095.5)	(1,248.2)
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
Intercompany loans payable	(3,037.1)	(12,840.7)
Other liabilities	0.0	0.0
Total Liabilities	(9,132.6)	(14,088.9)
Shareholders' Equity	(19,444.1)	(36,349.8)
Total Liabilities and Shareholders' Equity	(28,576.7)	(50,438.7)
Ordinary A
Condensed Consolidating Financial Statements
Ordinary A shares	$ 0.0	$ 0.0