Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Balance Sheets) (Details) - USD ($) $ in Millions	Dec. 27, 2019	Dec. 28, 2018	Dec. 29, 2017	Dec. 30, 2016
Condensed Consolidating Financial Statements
Opioid-related litigation settlement liability	$ 1,643.4	$ 0.0
Current Assets:
Cash and cash equivalents	790.9	348.9	$ 1,260.9
Accounts receivable, net	577.5	623.3
Inventories	312.1	322.3
Prepaid expenses and other current assets	150.2	132.7
Intercompany receivable	0.0	0.0
Total current assets	1,830.7	1,427.2
Property, plant and equipment, net	896.5	982.0
Intangible assets, net	7,018.0	8,282.8
Investment in subsidiaries	0.0	0.0
Intercompany loan receivable	0.0	0.0
Other assets	593.7	185.3
Total Assets	10,338.9	10,877.3
Current Liabilities:
Current maturities of long-term debt	633.6	22.4
Accounts payable	139.8	147.5
Accrued payroll and payroll-related costs	105.2	124.0
Interest Payable, Current	62.9	77.6
Accrued and other current liabilities	485.4	572.2
Intercompany payable	0.0	0.0
Total current liabilities	1,426.9	943.7
Long-term debt	4,741.2	6,069.2
Pension and postretirement benefits	62.4	60.5
Environmental liabilities	60.0	59.7
Deferred income taxes	11.0	324.3
Other income tax liabilities	227.1	228.0
Intercompany loans payable	0.0	0.0
Other liabilities	226.2	304.6
Total Liabilities	8,398.2	7,990.0
Shareholders' equity	1,940.7	2,887.3	6,522.0	$ 4,984.3
Total Liabilities and Shareholders' Equity	10,338.9	10,877.3
Mallinckrodt plc
Condensed Consolidating Financial Statements
Opioid-related litigation settlement liability	43.4
Current Assets:
Cash and cash equivalents	0.8	0.4	0.7
Accounts receivable, net	0.0	0.0
Inventories	0.0	0.0
Prepaid expenses and other current assets	9.0	3.9
Intercompany receivable	138.8	131.1
Total current assets	148.6	135.4
Property, plant and equipment, net	0.0	0.0
Intangible assets, net	0.0	0.0
Investment in subsidiaries	1,602.0	2,481.6
Intercompany loan receivable	416.5	497.7
Other assets	0.0	0.0
Total Assets	2,167.1	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
Interest Payable, Current	0.0	0.0
Accrued and other current liabilities	2.3	0.6
Intercompany payable	180.6	226.7
Total current liabilities	183.0	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	226.4	227.4
Shareholders' equity	1,940.7	2,887.3
Total Liabilities and Shareholders' Equity	2,167.1	3,114.7
Mallinckrodt International Finance S.A.
Condensed Consolidating Financial Statements
Opioid-related litigation settlement liability	0.0
Current Assets:
Cash and cash equivalents	124.7	140.8	908.8
Accounts receivable, net	0.0	0.0
Inventories	0.0	0.0
Prepaid expenses and other current assets	0.3	0.2
Intercompany receivable	31.8	29.2
Total current assets	156.8	170.2
Property, plant and equipment, net	0.0	0.0
Intangible assets, net	0.0	0.0
Investment in subsidiaries	7,457.6	25,506.1
Intercompany loan receivable	0.0	0.0
Other assets	0.0	0.0
Total Assets	7,614.4	25,676.3
Current Liabilities:
Current maturities of long-term debt	614.2	22.1
Accounts payable	0.0	0.0
Accrued payroll and payroll-related costs	0.0	0.0
Interest Payable, Current	29.4	48.7
Accrued and other current liabilities	0.4	0.4
Intercompany payable	10.5	827.8
Total current liabilities	654.5	899.0
Long-term debt	1,946.4	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	2,199.3	12,840.7
Other liabilities	2.2	7.6
Total Liabilities	4,802.4	17,314.2
Shareholders' equity	2,812.0	8,362.1
Total Liabilities and Shareholders' Equity	7,614.4	25,676.3
Other Subsidiaries
Condensed Consolidating Financial Statements
Opioid-related litigation settlement liability	1,600.0
Current Assets:
Cash and cash equivalents	665.4	207.7	351.4
Accounts receivable, net	577.5	623.3
Inventories	312.1	322.3
Prepaid expenses and other current assets	140.9	128.6
Intercompany receivable	249.1	1,087.9
Total current assets	1,945.0	2,369.8
Property, plant and equipment, net	896.5	982.0
Intangible assets, net	7,018.0	8,282.8
Investment in subsidiaries	2,812.0	8,362.1
Intercompany loan receivable	1,782.8	12,343.0
Other assets	593.7	185.3
Total Assets	15,048.0	32,525.0
Current Liabilities:
Current maturities of long-term debt	19.4	0.3
Accounts payable	139.7	147.4
Accrued payroll and payroll-related costs	105.2	124.0
Interest Payable, Current	33.5	28.9
Accrued and other current liabilities	482.7	571.2
Intercompany payable	228.6	193.7
Total current liabilities	1,009.1	1,065.5
Long-term debt	2,794.8	2,502.3
Pension and postretirement benefits	62.4	60.5
Environmental liabilities	60.0	59.7
Deferred income taxes	11.0	324.3
Other income tax liabilities	227.1	228.0
Intercompany loans payable	0.0	0.0
Other liabilities	224.0	297.0
Total Liabilities	5,988.4	4,537.3
Shareholders' equity	9,059.6	27,987.7
Total Liabilities and Shareholders' Equity	15,048.0	32,525.0
Eliminations
Condensed Consolidating Financial Statements
Opioid-related litigation settlement liability	0.0
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 receivable	(419.7)	(1,248.2)
Total current assets	(419.7)	(1,248.2)
Property, plant and equipment, net	0.0	0.0
Intangible assets, net	0.0	0.0
Investment in subsidiaries	(11,871.6)	(36,349.8)
Intercompany loan receivable	(2,199.3)	(12,840.7)
Other assets	0.0	0.0
Total Assets	(14,490.6)	(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
Interest Payable, Current	0.0	0.0
Accrued and other current liabilities	0.0	0.0
Intercompany payable	(419.7)	(1,248.2)
Total current liabilities	(419.7)	(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	(2,199.3)	(12,840.7)
Other liabilities	0.0	0.0
Total Liabilities	(2,619.0)	(14,088.9)
Shareholders' equity	(11,871.6)	(36,349.8)
Total Liabilities and Shareholders' Equity	$ (14,490.6)	$ (50,438.7)