Variation of Provision for Income Taxes from Statutory U.S. Federal Income Tax Rate (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Reconciliation of Statutory Federal Tax Rate [Line Items]
Income taxes computed at the statutory U.S. federal income tax rate	$ 78,325	$ 101,559	$ 77,588
State income taxes, net of federal tax benefit	5,978	8,557	5,910
Tax liabilities required	(182)	507	2,488
Valuation allowance	239	(6,662)	(88)
Manufacturing exemption	(6,865)	(5,128)	(6,834)
Tax credit refunds, net	(1,066)	(3,165)	(2,096)
Foreign earnings taxed at other than 35%	(566)	94	(2,406)
Deferred tax rate changes	(3,422)
Other		1,232	2,472
Provision for income taxes	$ 72,441	$ 96,994	$ 77,034
Effective tax rate	32.40%	33.40%	34.80%