Financial Assets and Liabilities Subject to Recurring Fair Value Measurements (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	$ 7.4	$ 2.5
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	1,177.7	1,192.7
Derivative assets	13.4	5.1
Derivative liabilities	93.0	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	221.4	218.6
Fair Value, Measurements, Recurring | U.S. corporate securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	65.7	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	0.5	0.8
Fair Value, Measurements, Recurring | Non-U.S. government securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	338.4	355.0
Fair Value, Measurements, Recurring | Non-U.S. corporate securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	438.6	448.7
Fair Value, Measurements, Recurring | Other debt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	113.1	109.5
Fair Value, Measurements, Recurring | Interest-rate swaps
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	1.7	1.6
Derivative liabilities	33.4	38.2
Fair Value, Measurements, Recurring | Cross currency swaps
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	11.0	3.0
Derivative liabilities	58.2	74.1
Fair Value, Measurements, Recurring | Foreign-exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	0.7	0.5
Derivative liabilities	1.4	0.7
Level 1 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	0.3	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	0.3	0.6
Level 2 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	1,177.4	1,192.1
Derivative assets	13.4	5.1
Derivative liabilities	93.0	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	221.4	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	65.7	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. government securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	338.4	355.0
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	438.6	448.7
Level 2 | Fair Value, Measurements, Recurring | Other debt securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Marketable debt securities	113.1	109.5
Level 2 | Fair Value, Measurements, Recurring | Interest-rate swaps
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	1.7	1.6
Derivative liabilities	33.4	38.2
Level 2 | Fair Value, Measurements, Recurring | Cross currency swaps
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	11.0	3.0
Derivative liabilities	58.2	74.1
Level 2 | Fair Value, Measurements, Recurring | Foreign-exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Derivative assets	0.7	0.5
Derivative liabilities	$ 1.4	$ 0.7