Consolidated and Combined Statement of Changes in Shareholders' Equity Statement - USD ($) $ in Millions	Total	Ordinary Shares	Treasury Shares	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income
Beginning balance, shares at Sep. 27, 2013		57,700,000	0
Beginning balance, value at Sep. 27, 2013	$ 1,255.6	$ 11.5	$ 0.0	$ 1,102.1	$ 33.5	$ 108.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(319.3)				(319.3)
Currency translation adjustments	(27.6)					(27.6)
Change in derivatives, net of tax	0.5					0.5
Minimum pension liability, net of tax	(15.7)					(15.7)
Net transfers to parent	3,979.6
Ordinary shares issued in connection with the Questcor acquisition, shares		57,300,000
Ordinary shares issued in connection with the Questcor acquisition, value		$ 11.4		3,968.2
Share options exercised, shares		800,000
Share options exercised, value	25.8	$ 0.2		25.6
Vesting of restricted shares, shares		400,000
Vesting of restricted shares, value	0.0	$ 0.1		(0.1)
Excess tax benefit from share-based compensation	8.9			8.9
Share-based compensation	67.7			67.7
Repurchase of ordinary shares, shares			200,000
Repurchase of ordinary shares, value	(17.5)		$ 17.5
Ending balance, shares at Sep. 26, 2014		116,200,000	200,000
Ending balance, value at Sep. 26, 2014	4,958.0	$ 23.2	$ (17.5)	5,172.4	(285.8)	65.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	324.7				324.7
Currency translation adjustments	(70.8)					(70.8)
Change in derivatives, net of tax	0.4					0.4
Minimum pension liability, net of tax	$ 5.6					(5.6)
Share options exercised, shares	1,132,778	1,200,000
Share options exercised, value	$ 34.4	$ 0.2		34.2
Vesting of restricted shares, shares		1,300,000
Vesting of restricted shares, value	0.0	$ 0.3		(0.3)
Shares canceled, shares		(1,200,000)
Shares canceled, value	0.0	$ (0.2)		(0.2)
Excess tax benefit from share-based compensation	34.1			34.1
Share-based compensation	117.0			117.0
Repurchase of ordinary shares, shares			1,000,000
Repurchase of ordinary shares, value	(92.2)		$ 92.2
Ending balance, shares at Sep. 25, 2015		117,500,000	1,200,000
Ending balance, value at Sep. 25, 2015	5,311.2	$ 23.5	$ (109.7)	5,357.6	38.9	0.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	643.7
Currency translation adjustments	(58.6)					(58.6)
Change in derivatives, net of tax	0.5					0.5
Minimum pension liability, net of tax	$ (28.4)					(28.4)
Share options exercised, shares	413,830	400,000
Share options exercised, value	$ 14.0	$ 0.1		13.9
Vesting of restricted shares, shares		200,000
Vesting of restricted shares, value	0.0	$ 0.0		0.0
Adjustments to Additional Paid in Capital, Income Tax Deficiency from Share-based Compensation	(1.7)			(1.7)
Share-based compensation	42.9			42.9
Repurchase of ordinary shares, shares			9,800,000
Repurchase of ordinary shares, value	(652.9)		$ 652.9
Ending balance, shares at Sep. 30, 2016		118,100,000	11,000,000
Ending balance, value at Sep. 30, 2016	$ 5,270.7	$ 23.6	$ (762.6)	$ 5,412.7	$ 682.6	$ (85.6)