Benefit Plans - Reconciliation of Benefit Obligations and Plan Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in benefit obligation:
Settlements	$ (88)		$ (253)
Pension Benefits [Member]
Change in benefit obligation:
Benefit obligation, beginning balance	3,227	$ 3,446
Service cost	8	12	16
Interest cost	128	127	149
Amendments/curtailments	1	(55)
Actuarial (gain) loss	72	(96)
Benefits paid from plan assets	(188)	(187)
Settlements	(101)	(12)
Foreign exchange	(16)	(8)
Benefit obligation, ending balance	3,131	3,227	3,446
Change in plan assets:
Fair value of plan assets, beginning balance	2,500	2,713
Actual return on plan assets	211	(21)
Company contributions	19	15
Benefits paid from plan assets	(188)	(187)
Settlements	(103)	(12)
Foreign exchange	(16)	(8)
Fair value of plan assets, ending balance	2,423	2,500	2,713
Funded status	(708)	(727)
Amounts recognized in the Consolidated Balance Sheets consist of:
Other assets	4	11
Other liabilities	(712)	(738)
Net amount recognized	(708)	(727)
Other Postretirement Benefits [Member]
Change in benefit obligation:
Benefit obligation, beginning balance	82	97
Service cost	1	1	1
Interest cost	3	3	4
Plan participants' contributions	5	5
Actuarial (gain) loss	(13)	(11)
Benefits paid from plan assets	(12)	(13)
Benefit obligation, ending balance	66	82	97
Change in plan assets:
Fair value of plan assets, beginning balance	86	87
Actual return on plan assets	3	2
Company contributions	4	5
Plan participants' contributions	5	5
Benefits paid from plan assets	(12)	(13)
Fair value of plan assets, ending balance	86	86	$ 87
Funded status	20	4
Amounts recognized in the Consolidated Balance Sheets consist of:
Other assets	44	38
Other liabilities	(24)	(34)
Net amount recognized	$ 20	$ 4