Condensed Consolidating Financial Statements (Schedule of Condensed Consolidating Statements of Cash Flows) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Mar. 25, 2016	Jun. 24, 2016	Jun. 26, 2015
Cash Flows From Operating Activities:
Net cash provided by operating activities		$ 994.4	$ 559.2
Cash Flows From Investing Activities:
Capital expenditures		(133.5)	(92.5)
Cash paid with acquisition		(169.5)	(1,176.3)
Proceeds from disposal of discontinued operations, net of cash		267.0	0.0
Intercompany loan investment, net		0.0	0.0
Investment in subsidiary		0.0	0.0
Restricted cash	$ 21.1	47.1	(21.9)
Other		5.3	2.6
Net cash provided by (used in) investing activities		16.4	(1,288.1)
Cash Flows From Financing Activities:
Issuance of external debt		98.3	1,720.0
Repayment of external debt and capital leases		(307.1)	(1,457.8)
Debt financing costs		(0.1)	(25.3)
Excess tax benefit from share-based compensation		0.0	30.4
Proceeds from exercise of share options		8.5	29.7
Repurchase of shares		(602.0)	(15.4)
Intercompany loan borrowings, net		0.0	0.0
Capital contribution		0.0	0.0
Other		(53.0)	(28.1)
Net cash (used in) provided by financing activities		(855.4)	253.5
Effect of currency rate changes on cash		0.6	(7.1)
Net increase in cash and cash equivalents		156.0	(482.5)
Cash and cash equivalents at beginning of period		365.9	707.8
Cash and cash equivalents at end of period		521.9	225.3
Mallinckrodt plc
Cash Flows From Operating Activities:
Net cash provided by operating activities		34.9	164.2
Cash Flows From Investing Activities:
Capital expenditures		0.0	0.0
Cash paid with acquisition		0.0	0.0
Proceeds from disposal of discontinued operations, net of cash		0.0
Intercompany loan investment, net		0.0	(178.6)
Investment in subsidiary		0.0	0.0
Restricted cash		0.0	0.0
Other		0.0	0.0
Net cash provided by (used in) investing activities		0.0	(178.6)
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
Excess tax benefit from share-based compensation			0.0
Proceeds from exercise of share options		8.5	29.7
Repurchase of shares		(602.0)	(15.4)
Intercompany loan borrowings, net		558.6	0.0
Capital contribution		0.0	0.0
Other		0.0	0.0
Net cash (used in) provided by financing activities		(34.9)	14.3
Effect of currency rate changes on cash		0.0	0.0
Net increase in cash and cash equivalents		0.0	(0.1)
Cash and cash equivalents at beginning of period		0.1	0.3
Cash and cash equivalents at end of period		0.1	0.2
Mallinckrodt International Finance S.A.
Cash Flows From Operating Activities:
Net cash provided by operating activities		(21.0)	(84.0)
Cash Flows From Investing Activities:
Capital expenditures		0.0	0.0
Cash paid with acquisition		0.0	0.0
Proceeds from disposal of discontinued operations, net of cash		234.0
Intercompany loan investment, net		0.0	0.0
Investment in subsidiary		(507.9)	(1,659.9)
Restricted cash		0.0	0.0
Other		0.0	0.0
Net cash provided by (used in) investing activities		(273.9)	(1,659.9)
Cash Flows From Financing Activities:
Issuance of external debt		0.0	1,640.0
Repayment of external debt and capital leases		(289.2)	(253.3)
Debt financing costs		0.0	(25.0)
Excess tax benefit from share-based compensation			0.0
Proceeds from exercise of share options		0.0	0.0
Repurchase of shares		0.0	0.0
Intercompany loan borrowings, net		520.8	413.6
Capital contribution		0.0	0.0
Other		0.0	0.0
Net cash (used in) provided by financing activities		231.6	1,775.3
Effect of currency rate changes on cash		0.0	0.0
Net increase in cash and cash equivalents		(63.3)	31.4
Cash and cash equivalents at beginning of period		152.1	18.5
Cash and cash equivalents at end of period		88.8	49.9
Other Subsidiaries
Cash Flows From Operating Activities:
Net cash provided by operating activities		980.5	479.0
Cash Flows From Investing Activities:
Capital expenditures		(133.5)	(92.5)
Cash paid with acquisition		(169.5)	(1,176.3)
Proceeds from disposal of discontinued operations, net of cash		33.0
Intercompany loan investment, net		(1,079.4)	(235.0)
Investment in subsidiary		0.0	0.0
Restricted cash		47.1	(21.9)
Other		5.3	2.6
Net cash provided by (used in) investing activities		(1,297.0)	(1,523.1)
Cash Flows From Financing Activities:
Issuance of external debt		98.3	80.0
Repayment of external debt and capital leases		(17.9)	(1,204.5)
Debt financing costs		(0.1)	(0.3)
Excess tax benefit from share-based compensation			30.4
Proceeds from exercise of share options		0.0	0.0
Repurchase of shares		0.0	0.0
Intercompany loan borrowings, net		0.0	0.0
Capital contribution		507.9	1,659.9
Other		(53.0)	(28.1)
Net cash (used in) provided by financing activities		535.2	537.4
Effect of currency rate changes on cash		0.6	(7.1)
Net increase in cash and cash equivalents		219.3	(513.8)
Cash and cash equivalents at beginning of period		213.7	689.0
Cash and cash equivalents at end of period		433.0	175.2
Eliminations
Cash Flows From Operating Activities:
Net cash provided by operating activities		0.0	0.0
Cash Flows From Investing Activities:
Capital expenditures		0.0	0.0
Cash paid with acquisition		0.0	0.0
Proceeds from disposal of discontinued operations, net of cash		0.0
Intercompany loan investment, net		1,079.4	413.6
Investment in subsidiary		507.9	1,659.9
Restricted cash		0.0	0.0
Other		0.0	0.0
Net cash provided by (used in) investing activities		1,587.3	2,073.5
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
Excess tax benefit from share-based compensation			0.0
Proceeds from exercise of share options		0.0	0.0
Repurchase of shares		0.0	0.0
Intercompany loan borrowings, net		(1,079.4)	(413.6)
Capital contribution		(507.9)	(1,659.9)
Other		0.0	0.0
Net cash (used in) provided by financing activities		(1,587.3)	(2,073.5)
Effect of currency rate changes on cash		0.0	0.0
Net increase in cash and cash equivalents		0.0	0.0
Cash and cash equivalents at beginning of period		0.0	0.0
Cash and cash equivalents at end of period		$ 0.0	$ 0.0