Pensions and Other Employee Benefits - 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 [Member]
Net periodic benefit cost:
Discount rate	5.02%	5.57%	6.26%
Expected long-term return on plan assets	8.15%	8.57%	8.55%
Rate of compensation increase	4.06%	4.50%	4.50%
Postretirement Benefit Plans [Member]
Net periodic benefit cost:
Discount rate	4.71%	5.40%	5.94%
Expected long-term return on plan assets	7.64%	6.20%	6.20%
Rate of compensation increase	4.09%	4.50%	4.50%