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]
Amortized Cost	$ 277.0	$ 377.5
Unrealized Gain	0.3	3.2
Unrealized Loss	(2.8)
Fair Value	274.5	380.7
U.S. government debt obligations
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	52.8	31.1
Unrealized Loss	(0.8)
Fair Value	52.0	31.1
Corporate debt obligations
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	58.2	9.5
Unrealized Gain		0.1
Unrealized Loss	(0.5)
Fair Value	57.7	9.6
Mortgaged backed debt obligations guaranteed by GNMA
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	105.4	54.9
Unrealized Gain	0.2	0.6
Unrealized Loss	(1.5)
Fair Value	104.1	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 government debt obligations
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	26.4	159.3
Unrealized Gain		1.8
Fair Value	26.4	161.1
Foreign corporate debt obligations guaranteed by foreign governments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	33.0	121.5
Unrealized Gain	0.1	0.7
Fair Value	$ 33.1	$ 122.2