Investments in Marketable Securities with Unrealized Losses (Detail) (USD $) In Millions, unless otherwise specified	Mar. 29, 2013
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Less than 12 months, Fair Value	$ 71.7
Unrealized Loss Less than 12 months, Unrealized Loss	(0.3)
Unrealized Loss Greater than 12 months, Fair Value
Unrealized Loss Greater than 12 months, Unrealized Loss
Total, Fair Value	71.7
Total, Unrealized Loss	(0.3)
Corporate debt obligations
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Less than 12 months, Fair Value	28.8
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	28.8
Total, Unrealized Loss	(0.1)
Mortgaged backed debt obligations guaranteed by GNMA
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Less than 12 months, Fair Value	42.9
Unrealized Loss Less than 12 months, Unrealized Loss	(0.2)
Unrealized Loss Greater than 12 months, Fair Value
Unrealized Loss Greater than 12 months, Unrealized Loss
Total, Fair Value	42.9
Total, Unrealized Loss	$ (0.2)