Investments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 02, 2016	Jun. 27, 2015	Jul. 02, 2016	Dec. 31, 2015	Jun. 27, 2015	Apr. 02, 2016
Unrealized Gain (Loss) on Investments [Abstract]
Equity securities, at cost less impairments	$ 20.2		$ 20.2	$ 6.4
Gross unrealized gains	19.8		19.8	9.3
Gross unrealized losses	0.0		0.0	(0.8)
Estimated fair value of equity securities	40.0		40.0	14.9
Impairment charges	1.7
Loss from equity method investments	1.6	$ 5.0		3.9	$ 5.3
Impairment	22.3
Transfer from investments			15.5
Unrealized gain, net of tax			8.7
Other non-current assets
Unrealized Gain (Loss) on Investments [Abstract]
Cost method investments	$ 7.0		$ 7.0	6.9
Equity method investments				$ 45.5		$ 4.8