Weighted-Average Assumptions used to Determine Domestic Net Periodic Benefit Cost (Detail)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
United States Pension Plans of US Entity, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.05%	5.90%	6.00%
Net Periodic Benefit Costs | United States Pension Plans of US Entity, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.90%	6.00%	6.50%
Expected long-term return on plan assets	8.00%	8.50%	8.50%
Rate of compensation increase	4.00%	4.00%	4.00%
Net Periodic Benefit Costs | United States Postretirement Benefit Plans of US Entity, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.90%	6.00%	6.50%