Investments (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 01, 2016	Sep. 26, 2015	Oct. 01, 2016	Sep. 26, 2015	Dec. 31, 2015
Unrealized Gain (Loss) on Investments [Abstract]
Equity securities, at cost less impairments	$ 20.1		$ 20.1		$ 6.4
Gross unrealized gains	32.9		32.9		9.3
Gross unrealized losses	0.0		0.0		(0.8)
Estimated fair value of equity securities	53.0		53.0		14.9
Other than temporary impairment losses			1.8
Equity method investment, other than temporary impairment			22.3
Transfer from investments			15.5
Unrealized gain (loss) on investments			8.7
Gain (loss) from equity method investments	0.1	$ (2.4)	(3.8)	$ (7.7)
Other non-current assets
Unrealized Gain (Loss) on Investments [Abstract]
Cost method investments	7.0		7.0		6.9
Equity method investments	$ 4.9		$ 4.9		$ 45.5