Weighted Average Assumptions Used in Pension Plans to Determine Periodic Benefit Cost (Detail) (Pension Plans, Defined Benefit)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension Plans, Defined Benefit
Schedule of Net Periodic Benefit Costs Weighted Average Assumptions [Line Items]
Discount rate	5.40%	6.00%	6.60%
Expected long-term rate of return on plan assets	6.75%	6.75%	8.25%
Rate of compensation increase