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Weighted Average Assumptions used to Determine Net Periodic Benefit Obligations and Costs (Detail)
12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Weighted average assumptions used to determine net periodic benefit obligations at December 31:      
Discount rate 5.40% 5.30%  
Weighted average assumptions used to determine net periodic benefit cost for the years ended December 31:      
Expected return on plan assets 6.50% 5.30%  
Domestic Plan
     
Weighted average assumptions used to determine net periodic benefit obligations at December 31:      
Discount rate 4.80% 5.30%  
Weighted average assumptions used to determine net periodic benefit cost for the years ended December 31:      
Discount rate 5.75% 5.85% 5.67%
Expected return on plan assets 5.75% 7.05% 6.87%
Rate of compensation increase   1.49% 2.34%
TCN Plan
     
Weighted average assumptions used to determine net periodic benefit obligations at December 31:      
Discount rate 4.80% 5.25%  
Rate of compensation increase   4.50%  
Weighted average assumptions used to determine net periodic benefit cost for the years ended December 31:      
Discount rate 5.75% 5.25% 6.00%
Expected return on plan assets 5.75% 7.50% 6.80%
Rate of compensation increase 4.50% 4.50% 4.50%