Investments and Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Dec. 29, 2012	Jun. 30, 2012
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	$ 423.3	$ 337.3
Gross Unrealized Gains	4.1	1.7
Gross Unrealized Losses	(0.5)	(0.5)
Available for Sale Investments at Fair Value	426.9	338.5
Gross unrealized losses on available-for-sale securities
Term of maturities of securities classified as current assets included in short-term investments	12 months	12 months
Gross unrealized losses, Less than 12 Months	0.1	0.1
Gross unrealized losses, Greater than 12 Months	0.4	0.4
Total gross unrealized losses	0.5	0.5
Cash and cash equivalents
Available-For-Sale Investments
Available for Sale Investments at Fair Value	26.6	21.3
Short-term investments
Available-For-Sale Investments
Available for Sale Investments at Fair Value	398.9	315.9
Other non-current assets
Available-For-Sale Investments
Available for Sale Investments at Fair Value	1.4	1.3
Debt securities
Contractual maturities of debt securities classified as available-for-sale securities, Amortized cost
Amortized cost of amounts maturing in less than 1 year	241.3
Amortized cost of amounts maturing in 1-5 years	180.6
Amortized cost of amounts maturing more than 5 years	1.4
Total amortized cost of debt securities	423.3
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	244.4
Estimated fair value amounts maturing in 1 -5 years	181.1
Estimated fair value amounts maturing in more than 5 years	1.4
Total estimated fair value of debt securities	426.9
Asset-backed securities
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	40.2	21.9
Gross Unrealized Gains	0.3	0.2
Gross Unrealized Losses	(0.4)	(0.4)
Available for Sale Investments at Fair Value	40.1	21.7
Gross unrealized losses on available-for-sale securities
Gross unrealized losses, Greater than 12 Months	0.4	0.4
Total gross unrealized losses	0.4	0.4
U.S. treasuries
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	71.9	52.0
Available for Sale Investments at Fair Value	71.9	52.0
U.S. Agencies
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	53.4	65.1
Gross Unrealized Gains	0.1	0.2
Available for Sale Investments at Fair Value	53.5	65.3
Foreign Agencies
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	4.0	3.3
Gross Unrealized Gains	0.1
Available for Sale Investments at Fair Value	4.1	3.3
Municipal bonds and sovereign debt instruments
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	6.6	11.4
Available for Sale Investments at Fair Value	6.6	11.4
Corporate securities
Available-For-Sale Investments
Amortized Cost/ Carrying Cost		183.6
Gross Unrealized Gains		1.3
Gross Unrealized Losses		(0.1)
Available for Sale Investments at Fair Value		184.8
Gross unrealized losses on available-for-sale securities
Gross unrealized losses, Less than 12 Months	0.1	0.1
Total gross unrealized losses	0.1	0.1
U.S.
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	213.8
Gross Unrealized Gains	1.4
Gross Unrealized Losses	(0.1)
Available for Sale Investments at Fair Value	215.1
Foreign
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	33.4
Gross Unrealized Gains	2.2
Available for Sale Investments at Fair Value	$ 35.6