Statutory U.S. Federal Income Tax Rate Reconcilation to Effective Income Tax Rates (Detail)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Reconciliation of Provision of Income Taxes [Line Items]
Statutory U.S. federal income tax rate	35.00%	35.00%	35.00%
State income taxes, net of related federal income tax benefit	1.40%	1.60%	1.60%
Benefits and taxes related to foreign operations	(4.70%)	(6.90%)	(6.30%)
Other, net	(0.40%)	(0.40%)	(0.50%)
Effective income tax rates	31.30%	29.30%	29.80%