Balance Sheet Components - Available-for-Sale Securities (Detail) - USD ($) $ in Millions	Oct. 02, 2015	Sep. 26, 2014
Available-for-sale Securities:
Amortized Cost	$ 93.2	$ 75.6
Gross Unrealized Gains	0.1	0.0
Gross Unrealized Losses	(0.3)	0.0
Fair Value	93.0	75.6
CPTC loans
Available-for-sale Securities:
Amortized Cost	83.9	75.6
Gross Unrealized Gains	0.0	0.0
Gross Unrealized Losses	0.0	0.0
Fair Value	83.9	$ 75.6
Other
Available-for-sale Securities:
Amortized Cost	8.6
Gross Unrealized Gains	0.1
Gross Unrealized Losses	(0.3)
Fair Value	8.4
Non-U.S. government security
Available-for-sale Securities:
Amortized Cost	0.7
Gross Unrealized Gains	0.0
Gross Unrealized Losses	0.0
Fair Value	$ 0.7

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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