Nonoperating Income (Expense) (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	6 Months Ended
	Apr. 01, 2016	Jun. 30, 2017	Jul. 01, 2016
Component of Operating Income [Abstract]
Proceeds from sale of marketable securities	$ 265.0	$ 0.0	$ 264.8
Marketable securities, realized gain			223.0
Marketable securities, after tax realized gain			$ 140.0
Marketable securities, after-tax gain, per diluted share			$ 0.20