Comprehensive Income (Detail) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Comprehensive Income (Loss) [Line Items]
Net income:	$ 30,464	$ 20,075	$ 91,878	$ 59,591
Other comprehensive loss, net of tax effect:
Foreign currency translation adjustments	(5,352)	7,415	(3,828)	1,086
Unrealized (loss) gain on interest rate swaps	(3,170)	673	(4,902)	2,257
Amortization of pension unrealized gain	(33)	(56)	(100)	(169)
Other comprehensive loss	(8,555)	8,032	(8,830)	3,174
Comprehensive income	$ 21,909	$ 28,107	$ 83,048	$ 62,765