Summary of Securities (Detail) (USD $) In Millions, unless otherwise specified	Sep. 28, 2014	Dec. 29, 2013
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Fair Value	$ 2.4
Short-term Investments
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Amortized Cost	0.2	0.1
Gross Unrealized Losses
Fair Value	0.2	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
Fair Value	0.1	0.1
Short-term Investments | Corporate Debt Securities
Schedule of Fair Value of Separate Accounts by Major Category of Investment [Line Items]
Amortized Cost	0.1
Gross Unrealized Losses
Fair Value	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
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
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
Fair Value	$ 0.2	$ 0.1