Income Taxes - Pre-tax Income and the Provision for Income Taxes (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Dec. 31, 2015	Dec. 27, 2014	Dec. 31, 2017	Dec. 31, 2016	Jun. 27, 2015
Pre-tax income:
Ireland	$ 8.9	$ 210.0	$ 280.1	$ (4,848.3)	$ 260.3
Other	319.1		734.1	(1,224.2)	1,053.1
Total pre-tax income (loss)	8.9		280.1	(4,848.3)	260.3
Current:
Ireland	1.6		(8.1)	0.3	(2.2)
Subtotal	116.5		138.4	120.7	149.2
Deferred (credit):
Ireland	(23.1)		13.1	(549.4)	11.1
Subtotal	(150.1)		22.1	(956.2)	(25.0)
Total (benefit) provision for income taxes	(33.6)	$ 29.4	160.5	(835.5)	124.2
United States
Current:
United States - federal	58.9		96.4	93.0	77.2
United States - state	3.0		4.0	0.7	6.8
Deferred (credit):
United States - federal	(34.4)		6.8	(7.6)	(19.9)
United States - state	(3.3)		1.0	(5.1)	(0.8)
Other Income Tax Authority
Current:
Other foreign	53.0		46.1	26.7	67.4
Deferred (credit):
Other foreign	(89.3)		1.2	(394.1)	(15.4)
Ireland
Pre-tax income:
Ireland	$ (310.2)		$ (454.0)	$ (3,624.1)	$ (792.8)