Financial Instruments - Carrying Amount and Estimated Fair Value of Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Carrying Amount [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	$ 478,573	[1]	$ 405,505	[1]
Credit facilities and bank overdrafts	12,335	[2]	984	[2]
Carrying Amount [Member] | Senior Notes - 2007 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	500,000	[3]	500,000	[3]
Carrying Amount [Member] | Senior Notes - 2006 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	125,000	[3]	125,000	[3]
Carrying Amount [Member] | Senior Notes - 2013 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	299,782	[3]	299,736	[3]
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	478,573	[1]	405,505	[1]
Credit facilities and bank overdrafts	12,335	[2]	984	[2]
Fair Value [Member] | Senior Notes - 2007 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	587,650	[3]	590,024	[3]
Fair Value [Member] | Senior Notes - 2006 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	133,137	[3]	139,146	[3]
Fair Value [Member] | Senior Notes - 2013 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt	$ 296,290	[3]	$ 278,770	[3]

[1] The carrying amount of cash and cash equivalents approximates fair value due to the short maturity of those instruments.

[2] The carrying amount of our credit facilities and bank overdrafts approximates fair value as the interest rate is reset frequently based on current market rates as well as the short maturity of those instruments.

[3] The fair value of our long-term debt was calculated using discounted cash flows applying current interest rates and current credit spreads based on our own credit risk.