Financial Assets and Liabilities Subject to Recurring Fair Value Measurements (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	$ 20.2	$ 31.7
Derivative liabilities	55.8	52.3
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	1,335.0	1,267.5
Derivative assets	31.0	48.0
Derivative liabilities	66.6	68.6
Fair Value, Measurements, Recurring | U.S. tax-exempt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	330.3	216.1
Fair Value, Measurements, Recurring | U.S. corporate securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	60.2	78.2
Fair Value, Measurements, Recurring | U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	5.6	5.5
Fair Value, Measurements, Recurring | Non-U.S. corporate securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	650.7	609.3
Fair Value, Measurements, Recurring | Non-U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	201.5	217.5
Fair Value, Measurements, Recurring | Other debt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	86.7	140.9
Fair Value, Measurements, Recurring | Cross currency swaps
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	27.3	40.9
Derivative liabilities	38.9	42.1
Fair Value, Measurements, Recurring | Interest-rate swaps
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	3.2	5.4
Derivative liabilities	23.6	25.6
Fair Value, Measurements, Recurring | Foreign-exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	0.5	1.7
Derivative liabilities	4.1	0.9
Level 1 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	5.3	5.2
Level 1 | Fair Value, Measurements, Recurring | U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	5.3	5.2
Level 2 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	1,329.7	1,262.3
Derivative assets	31.0	48.0
Derivative liabilities	66.6	68.6
Level 2 | Fair Value, Measurements, Recurring | U.S. tax-exempt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	330.3	216.1
Level 2 | Fair Value, Measurements, Recurring | U.S. corporate securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	60.2	78.2
Level 2 | Fair Value, Measurements, Recurring | U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	0.3	0.3
Level 2 | Fair Value, Measurements, Recurring | Non-U.S. corporate securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	650.7	609.3
Level 2 | Fair Value, Measurements, Recurring | Non-U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	201.5	217.5
Level 2 | Fair Value, Measurements, Recurring | Other debt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	86.7	140.9
Level 2 | Fair Value, Measurements, Recurring | Cross currency swaps
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	27.3	40.9
Derivative liabilities	38.9	42.1
Level 2 | Fair Value, Measurements, Recurring | Interest-rate swaps
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	3.2	5.4
Derivative liabilities	23.6	25.6
Level 2 | Fair Value, Measurements, Recurring | Foreign-exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	0.5	1.7
Derivative liabilities	$ 4.1	$ 0.9