Weighted-Average Assumptions Used To Determine Net Periodic Benefit Cost (Detail)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	4.75%	5.34%	5.75%
Rate of Compensation increase	3.33%	3.68%	3.73%
Expected long-term rate of return on plan assets	5.35%	5.87%	5.76%
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	4.31%	5.28%	5.80%