Investments and Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Sep. 29, 2012	Jun. 30, 2012
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	$ 388.2	$ 337.3
Gross Unrealized Gains	2.3	1.7
Gross Unrealized Losses	(0.4)	(0.5)
Available for Sale Investments at Fair Value	390.1	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
Gross unrealized losses, Greater than 12 Months	0.4	0.4
Total gross unrealized losses	0.4	0.5
Cash and cash equivalents
Available-For-Sale Investments
Available for Sale Investments at Fair Value	27.3	21.3
Short-term investments
Available-For-Sale Investments
Available for Sale Investments at Fair Value	361.4	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	234.5
Amortized cost of amounts maturing in 1-5 years	152.2
Amortized cost of amounts maturing more than 5 years	1.5
Total amortized cost of debt securities	388.2
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	236.2
Estimated fair value amounts maturing in 1 -5 years	152.5
Estimated fair value amounts maturing in more than 5 years	1.4
Total estimated fair value of debt securities	390.1
Asset-backed securities
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	40.9	21.9
Gross Unrealized Gains	0.3	0.2
Gross Unrealized Losses	(0.4)	(0.4)
Available for Sale Investments at Fair Value	40.8	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	67.5	52.0
Gross Unrealized Gains	0.1
Available for Sale Investments at Fair Value	67.6	52.0
U.S. Agencies
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	72.0	65.1
Gross Unrealized Gains	0.1	0.2
Available for Sale Investments at Fair Value	72.1	65.3
Foreign Agencies
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	3.3	3.3
Available for Sale Investments at Fair Value	3.3	3.3
Municipal bonds & sovereign debt instruments
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	13.2	11.4
Available for Sale Investments at Fair Value	13.2	11.4
Corporate securities
Available-For-Sale Investments
Amortized Cost/ Carrying Cost	191.3	183.6
Gross Unrealized Gains	1.8	1.3
Gross Unrealized Losses		(0.1)
Available for Sale Investments at Fair Value	193.1	184.8
Gross unrealized losses on available-for-sale securities
Gross unrealized losses, Less than 12 Months		0.1
Total gross unrealized losses		$ 0.1