Financial Assets and Liabilities Subject to Recurring Fair Value Measurements (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	$ 18.5	$ 2.5
Derivative liabilities	63.1	110.4
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	1,201.1	1,192.7
Derivative assets	30.9	5.1
Derivative liabilities	75.5	113.0
Fair Value, Measurements, Recurring | U.S. tax-exempt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	206.4	218.6
Fair Value, Measurements, Recurring | U.S. corporate securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	79.7	60.1
Fair Value, Measurements, Recurring | U.S. government and agency securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	0.6	0.8
Fair Value, Measurements, Recurring | Non-U.S. corporate securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	565.6	448.7
Fair Value, Measurements, Recurring | Non-U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	244.5	355.0
Fair Value, Measurements, Recurring | Other debt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	104.3	109.5
Fair Value, Measurements, Recurring | Cross currency swaps
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	26.8	3.0
Derivative liabilities	42.9	74.1
Fair Value, Measurements, Recurring | Interest-rate swaps
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	3.5	1.6
Derivative liabilities	28.1	38.2
Fair Value, Measurements, Recurring | Foreign-exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	0.6	0.5
Derivative liabilities	4.5	0.7
Level 1 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	0.4	0.6
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	0.4	0.6
Level 2 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	1,200.7	1,192.1
Derivative assets	30.9	5.1
Derivative liabilities	75.5	113.0
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	206.4	218.6
Level 2 | Fair Value, Measurements, Recurring | U.S. corporate securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	79.7	60.1
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	0.2	0.2
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	565.6	448.7
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	244.5	355.0
Level 2 | Fair Value, Measurements, Recurring | Other debt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	104.3	109.5
Level 2 | Fair Value, Measurements, Recurring | Cross currency swaps
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	26.8	3.0
Derivative liabilities	42.9	74.1
Level 2 | Fair Value, Measurements, Recurring | Interest-rate swaps
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	3.5	1.6
Derivative liabilities	28.1	38.2
Level 2 | Fair Value, Measurements, Recurring | Foreign-exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	0.6	0.5
Derivative liabilities	$ 4.5	$ 0.7