Stock Plans (Summary of Stock Option Activity) (Details) $ / shares in Units, shares in Thousands, $ in Millions	9 Months Ended
	Oct. 04, 2015 USD ($) $ / shares shares
Stock option activity
Number of Shares, Outstanding at beginning of period | shares	2,828
Number of Shares, Granted | shares	490
Number of Shares, Exercised | shares	(751)
Number of Shares, Canceled | shares	(3)
Number of Shares, Forfeited | shares	(83)
Number of Shares, Outstanding at end of period | shares	2,481
Number of Shares, Exercisable at end of period | shares	1,599
Number of Shares, Vested and expected to vest in the future | shares	2,413
Weighted-Average Price, Outstanding at beginning of period	$ 26.11
Weighted-Average Price, Granted	46.25
Weighted-Average Price, Exercised	17.42
Weighted-Average Price, Canceled	22.49
Weighted-Average Price, Forfeited	31.43
Weighted-Average Price, Outstanding at end of period	32.54
Weighted-Average Price, Exercisable at end of period	26.48
Weighted-Average Price, Vested and expected to vest in the future	$ 32.28
Weighted-Average Remaining Contractual Term in Years, Outstanding at end of period	3 years 9 months
Weighted-Average Remaining Contractual Term in Years, Exercisable at end of period	2 years 8 months
Weighted-Average Remaining Contractual Term in Years, Vested and expected to vest in the future	3 years 8 months
Total Intrinsic Value, Outstanding at end of period | $	$ 42.4
Total Intrinsic Value, Exercisable at end of period | $	37.0
Total Intrinsic Value, Vested and expected to vest in the future | $	$ 41.9