Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Millions, unless otherwise specified	Dec. 28, 2012	Dec. 30, 2011
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	$ 380.7	$ 843.9
Other marketable securities	195.1	190.9
Derivative financial instruments		0.2
Total Assets	575.8	1,035.0
Loan related to other marketable securities	195.1	190.9
Derivative financial instruments	0.1	0.2
Total Liabilities	195.2	191.1
U.S. government debt obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	31.1	195.7
Corporate debt obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	9.6	201.5
Mortgaged backed debt obligations guaranteed by GNMA
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	55.5	91.2
Certificates of deposit guaranteed by FDIC
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	1.2	1.5
Foreign government debt obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	161.1	223.0
Foreign corporate debt obligations guaranteed by foreign governments
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	122.2	64.2
Corporate debt obligations guaranteed By FDIC
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities		66.8
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	31.1	195.7
Other marketable securities	195.1	190.9
Total Assets	226.2	386.6
Loan related to other marketable securities	195.1	190.9
Total Liabilities	195.1	190.9
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. government debt obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	31.1	195.7
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	349.6	648.2
Derivative financial instruments		0.2
Total Assets	349.6	648.4
Derivative financial instruments	0.1	0.2
Total Liabilities	0.1	0.2
Significant Other Observable Inputs (Level 2) | Corporate debt obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	9.6	201.5
Significant Other Observable Inputs (Level 2) | Mortgaged backed debt obligations guaranteed by GNMA
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	55.5	91.2
Significant Other Observable Inputs (Level 2) | Certificates of deposit guaranteed by FDIC
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	1.2	1.5
Significant Other Observable Inputs (Level 2) | Foreign government debt obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	161.1	223.0
Significant Other Observable Inputs (Level 2) | Foreign corporate debt obligations guaranteed by foreign governments
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	122.2	64.2
Significant Other Observable Inputs (Level 2) | Corporate debt obligations guaranteed By FDIC
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities		$ 66.8