Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Statements of Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 29, 2018	Jun. 30, 2017	Jun. 29, 2018	Jun. 30, 2017
Condensed Consolidating Financial Statements
Net sales	$ 631.7	$ 600.1	$ 1,204.3	$ 1,160.1
Cost of sales	314.7	280.4	610.5	540.3
Gross profit	317.0	319.7	593.8	619.8
Selling, general and administrative expenses	164.3	214.6	356.7	432.2
Research and development expenses	81.3	52.3	145.4	97.3
Restructuring charges, net	58.7	0.6	81.8	10.9
Losses (gains) on divestiture and license	0.0	2.1	0.0	(57.0)
Operating income	12.7	50.1	9.9	136.4
Interest expense	(95.1)	(92.2)	(186.5)	(186.4)
Interest income	1.4	0.6	4.6	1.5
Other (expense) income, net	(0.5)	6.3	4.1	(73.6)
Intercompany Interest And Fees	0.0	0.0	0.0	0.0
Income (Loss) from Equity Method Investments	0.0	0.0	0.0	0.0
Loss from continuing operations before income taxes	(81.5)	(35.2)	(167.9)	(122.1)
Income tax benefit	(53.4)	(53.6)	(96.8)	(95.6)
Income (Loss) from Continuing Operations	(28.1)	18.4	(71.1)	(26.5)
Income from discontinued operations, net of income taxes	43.7	44.4	68.7	488.5
Net Income (Loss)	15.6	62.8	(2.4)	462.0
Other Comprehensive Income (Loss), Net of Tax	(4.9)	1.9	(7.3)	64.5
Comprehensive Income (Loss)	10.7	64.7	(9.7)	526.5
Mallinckrodt plc
Condensed Consolidating Financial Statements
Net sales	0.0	0.0	0.0	0.0
Cost of sales	0.7	0.9	0.9	0.9
Gross profit	(0.7)	(0.9)	(0.9)	(0.9)
Selling, general and administrative expenses	11.3	15.1	17.7	33.3
Research and development expenses	1.7	1.8	2.2	1.8
Restructuring charges, net	0.0	0.0	0.0	0.0
Losses (gains) on divestiture and license	0.0	0.0	0.0	0.0
Operating income	(13.7)	(17.8)	(20.8)	(36.0)
Interest expense	(1.6)	(3.4)	(4.6)	(6.7)
Interest income	2.2	2.0	4.4	3.1
Other (expense) income, net	0.6	2.2	6.7	17.6
Intercompany Interest And Fees	(4.0)	(3.5)	(8.5)	(9.0)
Income (Loss) from Equity Method Investments	31.0	81.0	18.1	489.7
Loss from continuing operations before income taxes	14.5	60.5	(4.7)	458.7
Income tax benefit	(1.1)	(1.3)	(2.3)	(3.3)
Income (Loss) from Continuing Operations	15.6	61.8	(2.4)	462.0
Income from discontinued operations, net of income taxes	0.0	1.0	0.0	0.0
Net Income (Loss)	15.6	62.8	(2.4)	462.0
Other Comprehensive Income (Loss), Net of Tax	(4.9)	1.9	(7.3)	64.5
Comprehensive Income (Loss)	10.7	64.7	(9.7)	526.5
Mallinckrodt International Finance S.A.
Condensed Consolidating Financial Statements
Net sales	0.0	0.0	0.0	0.0
Cost of sales	0.0	0.0	0.0	0.0
Gross profit	0.0	0.0	0.0	0.0
Selling, general and administrative expenses	0.2	0.2	0.4	0.4
Research and development expenses	0.0	0.0	0.0	0.0
Restructuring charges, net	0.0	0.0	0.0	0.0
Losses (gains) on divestiture and license	0.0	0.0	0.0	0.0
Operating income	(0.2)	(0.2)	(0.4)	(0.4)
Interest expense	(110.0)	(88.7)	(211.2)	(174.0)
Interest income	0.3	0.3	2.0	0.6
Other (expense) income, net	0.0	6.6	2.8	(3.3)
Intercompany Interest And Fees	0.0	0.0	0.0	0.0
Income (Loss) from Equity Method Investments	232.9	254.7	408.3	851.7
Loss from continuing operations before income taxes	123.0	172.7	201.5	674.6
Income tax benefit	(1.2)	(0.2)	(2.0)	(0.5)
Income (Loss) from Continuing Operations	124.2	172.9	203.5	675.1
Income from discontinued operations, net of income taxes	0.1	0.0	0.0	(1.7)
Net Income (Loss)	124.3	172.9	203.5	673.4
Other Comprehensive Income (Loss), Net of Tax	(4.9)	1.9	(7.3)	64.5
Comprehensive Income (Loss)	119.4	174.8	196.2	737.9
Other Subsidiaries
Condensed Consolidating Financial Statements
Net sales	631.7	600.1	1,204.3	1,160.1
Cost of sales	314.0	279.5	609.6	539.4
Gross profit	317.7	320.6	594.7	620.7
Selling, general and administrative expenses	152.8	199.3	338.6	398.5
Research and development expenses	79.6	50.5	143.2	95.5
Restructuring charges, net	58.7	0.6	81.8	10.9
Losses (gains) on divestiture and license	0.0	2.1	0.0	(57.0)
Operating income	26.6	68.1	31.1	172.8
Interest expense	(7.7)	(18.7)	(14.8)	(38.9)
Interest income	23.1	16.9	42.3	31.0
Other (expense) income, net	(1.1)	(2.5)	(5.4)	(87.9)
Intercompany Interest And Fees	4.0	3.5	8.5	9.0
Income (Loss) from Equity Method Investments	124.3	172.9	203.5	673.4
Loss from continuing operations before income taxes	169.2	240.2	265.2	759.4
Income tax benefit	(51.1)	(52.1)	(92.5)	(91.8)
Income (Loss) from Continuing Operations	220.3	292.3	357.7	851.2
Income from discontinued operations, net of income taxes	43.6	43.4	68.7	490.2
Net Income (Loss)	263.9	335.7	426.4	1,341.4
Other Comprehensive Income (Loss), Net of Tax	(9.9)	3.4	(15.1)	128.4
Comprehensive Income (Loss)	254.0	339.1	411.3	1,469.8
Eliminations
Condensed Consolidating Financial Statements
Net sales	0.0	0.0	0.0	0.0
Cost of sales	0.0	0.0	0.0	0.0
Gross profit	0.0	0.0	0.0	0.0
Selling, general and administrative expenses	0.0	0.0	0.0	0.0
Research and development expenses	0.0	0.0	0.0	0.0
Restructuring charges, net	0.0	0.0	0.0	0.0
Losses (gains) on divestiture and license	0.0	0.0	0.0	0.0
Operating income	0.0	0.0	0.0	0.0
Interest expense	24.2	18.6	44.1	33.2
Interest income	(24.2)	(18.6)	(44.1)	(33.2)
Other (expense) income, net	0.0	0.0	0.0	0.0
Intercompany Interest And Fees	0.0	0.0	0.0	0.0
Income (Loss) from Equity Method Investments	(388.2)	(508.6)	(629.9)	(2,014.8)
Loss from continuing operations before income taxes	(388.2)	(508.6)	(629.9)	(2,014.8)
Income tax benefit	0.0	0.0	0.0	0.0
Income (Loss) from Continuing Operations	(388.2)	(508.6)	(629.9)	(2,014.8)
Income from discontinued operations, net of income taxes	0.0	0.0	0.0	0.0
Net Income (Loss)	(388.2)	(508.6)	(629.9)	(2,014.8)
Other Comprehensive Income (Loss), Net of Tax	14.8	(5.3)	22.4	(192.9)
Comprehensive Income (Loss)	$ (373.4)	$ (513.9)	$ (607.5)	$ (2,207.7)