Fair Value Measurement of Assets and Liabilities - Fair Value Measurements of Assets and Liabilities (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value	$ 775.8	$ 915.7
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value	775.8	915.7
Total fair value measurement of assets	868.1	978.0
Fair Value, Measurements, Recurring [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, current and long-term	61.7	28.4
Derivatives, current and long-term	3.4	10.8
Fair Value, Measurements, Recurring [Member] | Interest rate swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, current and long-term	30.6	33.9
Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value	401.6	383.8
Fair Value, Measurements, Recurring [Member] | U.S. government agencies and debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value	263.9	295.9
Fair Value, Measurements, Recurring [Member] | Foreign government debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value	5.0	5.0
Fair Value, Measurements, Recurring [Member] | Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value	16.0	138.7
Fair Value, Measurements, Recurring [Member] | Certificates of deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value	89.3	92.3
Fair Value Measurements at Reporting Date Using: Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value	775.8	915.7
Total fair value measurement of assets	868.1	978.0
Fair Value Measurements at Reporting Date Using: Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Foreign exchange forward contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, current and long-term	61.7	28.4
Derivatives, current and long-term	3.4	10.8
Fair Value Measurements at Reporting Date Using: Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Interest rate swaps [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, current and long-term	30.6	33.9
Fair Value Measurements at Reporting Date Using: Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Corporate debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value	401.6	383.8
Fair Value Measurements at Reporting Date Using: Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | U.S. government agencies and debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value	263.9	295.9
Fair Value Measurements at Reporting Date Using: Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Foreign government debt securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value	5.0	5.0
Fair Value Measurements at Reporting Date Using: Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value	16.0	138.7
Fair Value Measurements at Reporting Date Using: Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member] | Certificates of deposit [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Fair Value	$ 89.3	$ 92.3