Summary of Securities (Detail) (USD $) In Millions, unless otherwise specified	Dec. 28, 2014	Dec. 29, 2013
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Fair Value	$ 2.3us-gaap_AvailableForSaleSecurities
Short-term Investments
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Amortized Cost	0.1	0.1
Gross Unrealized Losses	0	0
Fair Value	0.1	0.1
Short-term Investments \| U.S. Treasury securities and obligations of U.S. government agencies
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Amortized Cost	0.1	0.1
Gross Unrealized Losses	0	0
Fair Value	0.1	0.1
Long-Term Investments
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Amortized Cost	2.0	2.1
Gross Unrealized Gains	0.2	0.1
Gross Unrealized Losses	0	0
Fair Value	2.2	2.2
Long-Term Investments \| U.S. Treasury securities and obligations of U.S. government agencies
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Amortized Cost	1.8	2.0
Gross Unrealized Gains	0.2	0.1
Gross Unrealized Losses	0	0
Fair Value	2.0	2.1
Long-Term Investments \| Corporate Debt Securities
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Amortized Cost	0.2	0.1
Gross Unrealized Losses	0	0
Fair Value	$ 0.2	$ 0.1

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

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-Name Accounting Standards Codification

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

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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