Investments (Details) - USD ($) $ in Millions		3 Months Ended		12 Months Ended
		Mar. 31, 2018	Apr. 01, 2017	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Reclassification from OCI		$ (72.2)	$ (55.5)
ASU 2016-01
Schedule of Equity Method Investments [Line Items]
Reclassification from OCI				$ 1.4
Other expense (income), net
Schedule of Equity Method Investments [Line Items]
Equity securities, fair value method, other expense (income)		4.4	0.0
Equity securities, equity method, other expense (income)		0.2	$ (0.1)
Prepaid expenses and other current assets
Schedule of Equity Method Investments [Line Items]
Equity securities, prepaid expenses and other current assets, fair value method		13.8		17.0	[1]
Other non-current assets
Schedule of Equity Method Investments [Line Items]
Equity securities, fair value method, other non-current assets	[2]	5.1
Equity securities, fair value method, other non-current assets	[1]			6.3
Equity securities, equity method, other non-current assets		$ 4.7		4.9	[1]
Retained Earnings | ASU 2016-01
Schedule of Equity Method Investments [Line Items]
Reclassification to retained earnings				$ 1.4

[1] The December 31, 2017 balances presented reflect historical recognition and measurement investment categories existing prior to the adoption of ASU 2016-01, which include available for sale and cost method securities.

[2] The March 31, 2018 equity securities are measured at fair value using the Net Asset Value practical expedient.