Pensions and Other Employee Benefits - Weighted Average Assumptions Used to Determine Net Periodic Benefit Cost (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.14%	5.03%	4.15%
Expected long-term return on plan assets	8.14%	8.13%	8.13%
Rate of compensation increase	3.50%	3.50%	3.50%
Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	3.70%	4.43%	3.37%
Expected long-term return on plan assets	7.65%	7.64%	7.64%