Weighted Average Assumptions used to Determine Net Periodic Benefit Obligations and Net Periodic Benefit Cost (Detail)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
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	4.00%	4.80%
Rate of compensation increase
Weighted average assumptions used to determine net periodic benefit cost for the years ended December 31:
Discount rate	4.80%	5.75%	5.85%
Expected return on plan assets	6.50%	5.75%	7.05%
Rate of compensation increase			1.49%
TCN Plan
Weighted average assumptions used to determine net periodic benefit obligations at December 31:
Discount rate	4.00%	4.80%
Rate of compensation increase
Weighted average assumptions used to determine net periodic benefit cost for the years ended December 31:
Discount rate	4.80%	5.75%	5.25%
Expected return on plan assets	6.90%	5.75%	7.50%
Rate of compensation increase		4.50%	4.50%