Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Millions, unless otherwise specified	Mar. 29, 2013	Dec. 28, 2012
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	$ 201.3	$ 380.7
Other marketable securities	209.6	195.1
Derivative financial instruments	0.2
Total assets	411.1	575.8
Loan related to other marketable securities	209.6	195.1
Derivative financial instruments	0.2	0.1
Total Liabilities	209.8	195.2
U.S. government debt obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	18.5	31.1
Corporate debt obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	43.0	9.6
Mortgaged backed debt obligations guaranteed by GNMA
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	92.9	55.5
Certificates of deposit guaranteed by FDIC
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	1.7	1.2
Foreign government debt obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	20.5	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	24.7	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	18.5	31.1
Other marketable securities	209.6	195.1
Total assets	228.1	226.2
Loan related to other marketable securities	209.6	195.1
Total Liabilities	209.6	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	18.5	31.1
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	182.8	349.6
Derivative financial instruments	0.2
Total assets	183.0	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	43.0	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	92.9	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	1.7	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	20.5	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	$ 24.7	$ 122.2