Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Millions, unless otherwise specified	Sep. 27, 2013	Dec. 28, 2012
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	$ 234.6	$ 380.7
Other marketable securities	234.0	195.1
Derivative financial instruments	0.4
Total assets	469.0	575.8
Loan related to other marketable securities	234.0	195.1
Derivative financial instruments	0.1	0.1
Total liabilities	234.1	195.2
U.S. government debt obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	60.2	31.1
Corporate debt obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	53.5	9.6
Mortgaged backed debt obligations guaranteed by GNMA
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	94.1	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		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	25.6	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	60.2	31.1
Other marketable securities	234.0	195.1
Total assets	294.2	226.2
Loan related to other marketable securities	234.0	195.1
Total liabilities	234.0	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	60.2	31.1
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Investments in marketable securities	174.4	349.6
Derivative financial instruments	0.4
Total assets	174.8	349.6
Derivative financial instruments	0.1	0.1
Total liabilities	0.1	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	53.5	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	94.1	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		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	$ 25.6	$ 122.2