Reclassifications Out of Accumulated Other Comprehensive Loss (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income On Derivatives [Line Items]
Cost of sales	$ 549,813	$ 443,265	$ 1,541,903	$ 1,321,008
Income from Operations	131,229	104,384	376,649	313,545
Interest expense, net	(4,594)	(3,829)	(13,569)	(10,714)
Income tax expense	(41,074)	(30,441)	(117,655)	(95,351)
Net income	90,155	73,943	258,994	218,194
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Defined Benefit Plan Adjustment Net Prior Service Cost Credit
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income On Derivatives [Line Items]
Cost of sales	(613)		(1,843)
Reclassification out of Accumulated Other Comprehensive Income | Accumulated Defined Benefit Plan Adjustment Amortization Of Net Loss
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income On Derivatives [Line Items]
Cost of sales	1,368		4,751
Reclassification out of Accumulated Other Comprehensive Income | Pension And Post Retirement Benefit Plans
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income On Derivatives [Line Items]
Income from Operations	755		2,908
Income tax expense	(236)		(908)
Net income	519		2,000
Reclassification out of Accumulated Other Comprehensive Income | Derivative Contracts
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income On Derivatives [Line Items]
Interest expense, net	492		1,697
Income tax expense	(154)		(530)
Net income	$ 338		$ 1,167