Investments in Marketable Securities with Unrealized Losses (Detail) (USD $) In Millions, unless otherwise specified	Dec. 30, 2011
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Less than 12 months, Fair Value	$ 136.5
Unrealized Loss Less than 12 months, Unrealized Loss	(0.9)
Unrealized Loss Greater than 12 months, Fair Value
Unrealized Loss Greater than 12 months, Unrealized Loss
Total, Fair Value	136.5
Total, Unrealized Loss	(0.9)
Corporate debt obligations
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Less than 12 months, Fair Value	81.0
Unrealized Loss Less than 12 months, Unrealized Loss	(0.7)
Unrealized Loss Greater than 12 months, Fair Value
Unrealized Loss Greater than 12 months, Unrealized Loss
Total, Fair Value	81.0
Total, Unrealized Loss	(0.7)
Mortgaged backed debt obligations guaranteed by GNMA
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Less than 12 months, Fair Value	31.4
Unrealized Loss Less than 12 months, Unrealized Loss	(0.1)
Unrealized Loss Greater than 12 months, Fair Value
Unrealized Loss Greater than 12 months, Unrealized Loss
Total, Fair Value	31.4
Total, Unrealized Loss	(0.1)
Foreign corporate debt obligations guaranteed by foreign governments
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Less than 12 months, Fair Value	24.1
Unrealized Loss Less than 12 months, Unrealized Loss	(0.1)
Unrealized Loss Greater than 12 months, Fair Value
Unrealized Loss Greater than 12 months, Unrealized Loss
Total, Fair Value	24.1
Total, Unrealized Loss	$ (0.1)