Variation of the Provision for Income Taxes from the Statutory U.S. Federal Income Tax Rate (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Reconciliation of Statutory Federal Tax Rate [Line Items]
Income taxes computed at the statutory U.S. federal income tax rate	$ 101,559	$ 77,588	$ 86,660
State income taxes, net of federal tax benefit	8,557	5,910	6,345
Tax liabilities required	507	2,488	2,578
Valuation allowance	(6,662)	(88)	1,525
Manufacturing exemption	(5,128)	(6,834)	(3,138)
Tax credit refunds, net	(3,165)	(2,096)	(1,255)
Foreign earnings taxed at other than 35%	94	(2,406)	(2,292)
Other	1,232	2,472	(2,233)
Provision for income taxes	$ 96,994	$ 77,034	$ 88,190
Effective tax rate	33.40%	34.80%	35.60%