Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Millions, unless otherwise specified	Jun. 28, 2013	Dec. 28, 2012
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	$ 274.5	$ 380.7
Other marketable securities	244.1	195.1
Derivative financial instruments	0.7
Total assets	519.3	575.8
Loan related to other marketable securities	244.1	195.1
Derivative financial instruments	0.2	0.1
Total liabilities	244.3	195.2
U.S. government debt obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	52.0	31.1
Corporate debt obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	57.7	9.6
Mortgaged backed debt obligations guaranteed by GNMA
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	104.1	55.5
Certificates of deposit guaranteed by FDIC
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	1.2	1.2
Foreign government debt obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	26.4	161.1
Foreign corporate debt obligations guaranteed by foreign governments
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	33.1	122.2
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	52.0	31.1
Other marketable securities	244.1	195.1
Total assets	296.1	226.2
Loan related to other marketable securities	244.1	195.1
Total liabilities	244.1	195.1
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	52.0	31.1
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	222.5	349.6
Derivative financial instruments	0.7
Total assets	223.2	349.6
Derivative financial instruments	0.2	0.1
Total liabilities	0.2	0.1
Significant Other Observable Inputs (Level 2) | Corporate debt obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	57.7	9.6
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	104.1	55.5
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	1.2
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	26.4	161.1
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	$ 33.1	$ 122.2