Items Measured at Fair Value on a Recurring Basis (Detail) (Fair Value, Measurements, Recurring, USD $) In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets (Note 14)	$ 2.7		$ 2.0
Total assets	131.3		161.5
Derivative liabilities (Note 14)	6.0		2.7
Total liabilities	26.7		21.3
Bank time deposits with original maturities of three months or less | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank time deposits with original maturities of three months or less	107.7		140.7
Diversified investments associated with the Executive Stock Unit Program (ESUP) (Note 9) | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Diversified investments associated with the Executive Stock Unit Program (ESUP) (Note 9)	20.9	[1]	18.8
Liabilities Associated With Esup | Total
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities	20.7	[1]	18.6	[1]
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets (Note 14)	0		0
Total assets	20.9		18.8
Derivative liabilities (Note 14)	0		0
Total liabilities	20.7		18.6
Level 1 | Bank time deposits with original maturities of three months or less
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank time deposits with original maturities of three months or less	0		0
Level 1 | Diversified investments associated with the Executive Stock Unit Program (ESUP) (Note 9)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Diversified investments associated with the Executive Stock Unit Program (ESUP) (Note 9)	20.9	[1]	18.8
Level 1 | Liabilities Associated With Esup
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities	20.7	[1]	18.6	[1]
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets (Note 14)	2.7		2.0
Total assets	110.4		142.7
Derivative liabilities (Note 14)	6.0		2.7
Total liabilities	6.0		2.7
Level 2 | Bank time deposits with original maturities of three months or less
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank time deposits with original maturities of three months or less	107.7		140.7
Level 2 | Diversified investments associated with the Executive Stock Unit Program (ESUP) (Note 9)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Diversified investments associated with the Executive Stock Unit Program (ESUP) (Note 9)	0	[1]	0
Level 2 | Liabilities Associated With Esup
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities	0	[1]	0	[1]
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets (Note 14)	0		0
Total assets	0		0
Derivative liabilities (Note 14)	0		0
Total liabilities	0		0
Level 3 | Bank time deposits with original maturities of three months or less
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank time deposits with original maturities of three months or less	0		0
Level 3 | Diversified investments associated with the Executive Stock Unit Program (ESUP) (Note 9)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Diversified investments associated with the Executive Stock Unit Program (ESUP) (Note 9)	0	[1]	0
Level 3 | Liabilities Associated With Esup
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities	$ 0	[1]	$ 0	[1]

[1] Includes both current and long-term amounts combined.