Maturities of Available for Sale Marketable Securities (Detail) (USD $) In Millions, unless otherwise specified	Sep. 27, 2013	Dec. 28, 2012
Schedule of Available-for-sale Securities [Line Items]
Due in less than 12 months, amortized cost	$ 56.2
Due in 1 to 5 years, amortized cost	85.1
Due after 5 years, amortized cost	95.8
Total, amortized cost	237.1	377.5
Due in less than 12 months, fair value	56.3
Due in 1 to 5 years, fair value	84.1
Due after 5 years, fair value	94.2
Fair Value	$ 234.6	$ 380.7