Investments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016	Dec. 31, 2016
Unrealized Gain (Loss) on Investments [Abstract]
Impairment of investments				$ 1.8
Gain on sale of investments			$ 1.6
Gains (loss) from equity method investments	$ (0.1)	$ 0.1	0.2	(3.8)
Equity method investment, other than temporary impairment				22.3
Transfer from investments				15.5
Unrealized gain (loss) on investments				$ 8.7
Estimated fair value of equity securities
Unrealized Gain (Loss) on Investments [Abstract]
Equity securities, at cost less impairments	15.5		15.5		$ 16.5
Gross unrealized gains	0.0		0.0		21.7
Gross unrealized losses	9.4		9.4		0.0
Estimated fair value of equity securities	6.1		6.1		38.2
Other non-current assets
Unrealized Gain (Loss) on Investments [Abstract]
Cost method investments	7.2		7.2		6.9
Equity method investments	$ 4.8		$ 4.8		$ 4.6