Revenues Based on Domicile of Customers (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Segment Reporting Information [Line Items]
Total revenues	$ 461,162		$ 429,430
United States
Segment Reporting Information [Line Items]
Total revenues	305,500		292,700
Europe
Segment Reporting Information [Line Items]
Total revenues	73,000	[1]	65,800	[1]
Canada
Segment Reporting Information [Line Items]
Total revenues	50,800		44,100
Japan
Segment Reporting Information [Line Items]
Total revenues	18,400	[1]	17,400	[1]
Mexico
Segment Reporting Information [Line Items]
Total revenues	2,400		1,900
Other
Segment Reporting Information [Line Items]
Total revenues	$ 11,100		$ 7,500

[1] Revenues are impacted by movements in foreign currency exchange rates. Refer to the discussion under "Revenues" in the Results of Operations.