Investments (Investments In Marketable Securities With Unrealized Losses) (Details) (USD $) In Millions	Jul. 01, 2011	Dec. 31, 2010
Gross unrealized losses less than 12 months, Fair Value	$ 370.2	$ 507.3
Gross unrealized losses greater than 12 months, Fair Value	2.4
Total gross unrealized losses, Fair Value	372.6	507.3
Gross unrealized losses less than 12 months	(2.5)	(3.1)
Gross unrealized loss on investments, greater than 12 months	(0.1)
Total gross unrealized losses	(2.6)	(3.1)
U.S. Government Debt Obligations [Member]
Gross unrealized losses less than 12 months, Fair Value	27.1	218.6
Total gross unrealized losses, Fair Value	27.1	218.6
Gross unrealized losses less than 12 months	(0.1)	(0.7)
Total gross unrealized losses	(0.1)	(0.7)
Corporate Debt Obligations Guaranteed By FDIC [Member]
Gross unrealized losses less than 12 months, Fair Value	11.3
Total gross unrealized losses, Fair Value	11.3
Gross unrealized losses less than 12 months	(0.1)
Total gross unrealized losses	(0.1)
Corporate Debt Obligations [Member]
Gross unrealized losses less than 12 months, Fair Value	110.9	47.5
Total gross unrealized losses, Fair Value	110.9	47.5
Gross unrealized losses less than 12 months	(0.6)	(0.2)
Total gross unrealized losses	(0.6)	(0.2)
Foreign Government Debt Obligations Guaranteed By Foreign Governments [Member]
Gross unrealized losses less than 12 months, Fair Value	51.2	32.6
Total gross unrealized losses, Fair Value	51.2	32.6
Gross unrealized losses less than 12 months	(0.4)	(0.1)
Total gross unrealized losses	(0.4)	(0.1)
Mortgage-Backed Debt Obligations Guaranteed By GNMA [Member]
Gross unrealized losses less than 12 months, Fair Value	37.4	115.7
Gross unrealized losses greater than 12 months, Fair Value	2.4
Total gross unrealized losses, Fair Value	39.9	115.7
Gross unrealized losses less than 12 months	(0.3)	(1.2)
Gross unrealized loss on investments, greater than 12 months	(0.1)
Total gross unrealized losses	(0.4)	(1.2)
Foreign Government Debt Obligations [Member]
Gross unrealized losses less than 12 months, Fair Value	132.3	92.9
Total gross unrealized losses, Fair Value	132.3	92.9
Gross unrealized losses less than 12 months	(1.0)	(0.9)
Total gross unrealized losses	$ (1.0)	$ (0.9)