Pensions and Other Employee Benefits - Net Loss and Prior Service Cost Balances in Accumulated Other Comprehensive Loss Account (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net loss (gain)	$ 968	$ 425
Prior service cost (credit)		1
Total amount recognized	968	426
Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net loss (gain)	(6)	(9)
Prior service cost (credit)	(3)	(8)
Total amount recognized	$ (9)	$ (17)