Investments and Fair Value Measurements (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 27, 2015	Jun. 28, 2014	Jun. 29, 2013
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	$ 496.6	$ 588.8
Gross Unrealized Gains	0.1	0.3
Gross Unrealized Losses	(0.3)	(0.2)
Available for Sale Investments at Fair Value	496.4	588.9
Other-than-temporary impairment loss	0.0	0.0	$ 0.0
Gross unrealized losses on available-for-sale securities
Gross unrealized losses, Less than 12 Months	0.1
Gross unrealized losses, Greater than 12 Months	0.2	0.2
Total gross unrealized losses	0.3	0.2
Contractual maturities of debt securities classified as available-for-sale securities, Amortized cost
Amortized cost of amounts maturing in less than 1 year	360.2
Amortized cost of amounts maturing in 1-5 years	134.7
Amortized cost of amounts maturing in more than 5 years	1.7
Total amortized cost of debt available-for-sale securities	496.6
Contractual maturities of the debt securities classified as available-for-sale securities, Estimated fair value
Estimated fair value amounts maturing in less than 1 year	360.2
Estimated fair value amounts maturing in 1 -5 years	134.7
Estimated fair value amounts maturing in more than 5 years	1.5
Total estimated fair value of debt available-for-sale securities	$ 496.4
Term of maturities of securities classified as current assets included in short-term investments	12 months
Cash equivalents
Available-For-Sale Investments
Available for Sale Investments at Fair Value	$ 33.7	39.8
Short-term investment
Available-For-Sale Investments
Available for Sale Investments at Fair Value	461.9	548.3
Other non-current assets
Available-For-Sale Investments
Available for Sale Investments at Fair Value	0.8	0.8
Asset-backed securities
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	70.6	94.7
Gross Unrealized Gains		0.1
Gross Unrealized Losses	(0.2)	(0.2)
Available for Sale Investments at Fair Value	70.4	94.6
Gross unrealized losses on available-for-sale securities
Gross unrealized losses, Greater than 12 Months	0.2	0.2
Total gross unrealized losses	0.2	0.2
U.S. treasuries
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	51.9	36.8
Available for Sale Investments at Fair Value	51.9	36.8
U.S. Agencies
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	96.0	70.0
Available for Sale Investments at Fair Value	96.0	70.0
Municipal bonds and sovereign debt instruments
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	4.0	16.8
Available for Sale Investments at Fair Value	4.0	16.8
Corporate securities
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	274.1	370.5
Gross Unrealized Gains	0.1	0.2
Gross Unrealized Losses	(0.1)
Available for Sale Investments at Fair Value	274.1	$ 370.7
Gross unrealized losses on available-for-sale securities
Gross unrealized losses, Less than 12 Months	0.1
Total gross unrealized losses	$ 0.1