Gross Realized Gains and Losses Related to Fixed Income Investments (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 28, 2012		Dec. 30, 2011		Dec. 31, 2010
Schedule of Available-for-sale Securities [Line Items]
Gross realized gains	$ 4.4		$ 3.8		$ 14.9
Gross realized losses	(1.3)	[1]	(4.9)	[1]	(2.7)	[1]
Total	$ 3.1		$ (1.1)		$ 12.2

[1] Includes other-than-temporary impairments of $1.2 million for the year ended December 30, 2011.