Pension Plans, Postretirement and Other Employee Benefits - Amounts to be Reflected as Component of Net Periodic Cost (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ 5
Prior service cost	(2)
Total	3
Postretirement
Defined Benefit Plan Disclosure [Line Items]
Prior service cost	$ (6)	$ (10)