Investments (Investments In Marketable Securities With Unrealized Losses) (Details) (USD $) In Millions, unless otherwise specified	Mar. 30, 2012	Dec. 30, 2011
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Less than 12 months, Fair Value	$ 266.4	$ 136.5
Unrealized Loss Greater than 12 months, Fair Value
Total, Fair Value	266.4	136.5
Unrealized Loss Less than 12 months, Unrealized Loss	(0.6)	(0.9)
Unrealized Loss Greater than 12 months, Unrealized Loss
Total, Unrealized Loss	(0.6)	(0.9)
Mortgaged Backed Debt Obligations Guaranteed By GNMA [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Less than 12 months, Fair Value	24.0	31.4
Unrealized Loss Greater than 12 months, Fair Value
Total, Fair Value	24.0	31.4
Unrealized Loss Less than 12 months, Unrealized Loss	(0.2)	(0.1)
Unrealized Loss Greater than 12 months, Unrealized Loss
Total, Unrealized Loss	(0.2)	(0.1)
U.S. Government Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Less than 12 months, Fair Value	107.4
Unrealized Loss Greater than 12 months, Fair Value
Total, Fair Value	107.4
Unrealized Loss Less than 12 months, Unrealized Loss	(0.1)
Unrealized Loss Greater than 12 months, Unrealized Loss
Total, Unrealized Loss	(0.1)
Corporate Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Less than 12 months, Fair Value	54.5	81.0
Unrealized Loss Greater than 12 months, Fair Value
Total, Fair Value	54.5	81.0
Unrealized Loss Less than 12 months, Unrealized Loss	(0.2)	(0.7)
Unrealized Loss Greater than 12 months, Unrealized Loss
Total, Unrealized Loss	(0.2)	(0.7)
Foreign Government Debt Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Unrealized Loss Less than 12 months, Fair Value	80.5	24.1
Unrealized Loss Greater than 12 months, Fair Value
Total, Fair Value	80.5	24.1
Unrealized Loss Less than 12 months, Unrealized Loss	(0.1)	(0.1)
Unrealized Loss Greater than 12 months, Unrealized Loss
Total, Unrealized Loss	$ (0.1)	$ (0.1)