Maturities of Available for Sale Marketable Securities (Detail) (USD $) In Millions, unless otherwise specified	Jun. 28, 2013	Dec. 28, 2012
Schedule of Available-for-sale Securities [Line Items]
Due in less than 12 months, amortized cost	$ 65.3
Due in 1 to 5 years, amortized cost	106.4
Due after 5 years, amortized cost	105.3
Total, amortized cost	277.0	377.5
Due in less than 12 months, fair value	65.4
Due in 1 to 5 years, fair value	105.0
Due after 5 years, fair value	104.1
Fair Value	$ 274.5	$ 380.7