Employee Benefits - Net Pension Cost (Benefit) for All Funded and Unfunded Plans (Detail) - Pension Plans [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Interest cost on PBO	$ 11	$ 10	$ 21	$ 20
Expected return on plan assets	(13)	(14)	(26)	(28)
Amortization of losses	4	5	8	9
Net pension cost	$ 2	$ 1	$ 3	$ 1