Employee Benefits - Funded Status of Pension Plans Recognized in Balance Sheets (Detail) - Pension Plans [Member] - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Funded status	$ (205)	$ (267)
Net prepaid pension cost recognized consists of:
Current liabilities	(16)	(14)
Noncurrent liabilities	(189)	(253)
Net prepaid pension cost recognized	$ (205)	$ (267)