Comprehensive Income - Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Comprehensive Income Loss [Line Items]
Net income	$ 172,943	$ 151,832	$ 487,816	$ 430,159
Other comprehensive income (loss):
Foreign currency translation			29,727	(37,547)
Pension and other post-retirement benefit adjustments:
Recognition of prior service credit, net of tax			(3,715)	(3,931)
Recognition of actuarial loss, net of tax			35,181	14,438
Total other comprehensive income (loss)			61,193	(27,040)
Comprehensive income	$ 210,542	$ 84,920	$ 549,009	$ 403,119