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]
Amortized Cost	$ 237.1	$ 377.5
Unrealized Gain	0.1	3.2
Unrealized Loss	(2.6)
Fair Value	234.6	380.7
U.S. government debt obligations
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	60.9	31.1
Unrealized Loss	(0.7)
Fair Value	60.2	31.1
Corporate debt obligations
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	53.7	9.5
Unrealized Gain		0.1
Unrealized Loss	(0.2)
Fair Value	53.5	9.6
Mortgaged backed debt obligations guaranteed by GNMA
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	95.8	54.9
Unrealized Gain		0.6
Unrealized Loss	(1.7)
Fair Value	94.1	55.5
Certificates of deposit guaranteed by FDIC
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1.2	1.2
Fair Value	1.2	1.2
Foreign corporate debt obligations guaranteed by foreign governments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	25.5	121.5
Unrealized Gain	0.1	0.7
Fair Value	25.6	122.2
Foreign government debt obligations
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		159.3
Unrealized Gain		1.8
Fair Value		$ 161.1