Benefit Plans - Reconciliation of Benefit Obligations and Plan Assets (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Change in benefit obligation:
Settlements	$ (253)
Change in plan assets:
Settlements	(253)
Pension Benefits [Member]
Change in benefit obligation:
Benefit obligation, beginning balance	3,336	3,700
Service cost	16	22	24
Interest cost	149	136	151
Amendments/Curtailments	(4)	(13)
Actuarial (gain) loss	402	(313)
Benefits paid from plan assets	(178)	(178)
Settlements	(268)	(19)
Foreign exchange	(7)	1
Benefit obligation, ending balance	3,446	3,336	3,700
Change in plan assets:
Fair value of plan assets, beginning balance	2,914	2,672
Actual return on plan assets	233	340
Company contributions	19	98
Benefits paid from plan assets	(178)	(178)
Settlements	(268)	(19)
Foreign exchange	(7)	1
Fair value of plan assets, ending balance	2,713	2,914	2,672
Funded status	(733)	(422)
Amounts recognized in the Consolidated Balance Sheets consist of:
Other assets	9	9
Other liabilities	(742)	(431)
Net amount recognized	(733)	(422)
Other Postretirement Benefits [Member]
Change in benefit obligation:
Benefit obligation, beginning balance	101	122
Service cost	1	1	1
Interest cost	4	4	5
Plan participants' contributions	6	6
Amendments/Curtailments	(7)	(2)
Actuarial (gain) loss	7	(13)
Benefits paid from plan assets	(15)	(17)
Benefit obligation, ending balance	97	101	122
Change in plan assets:
Fair value of plan assets, beginning balance	81	87
Actual return on plan assets	9	(2)
Company contributions	6	7
Plan participants' contributions	6	6
Benefits paid from plan assets	(15)	(17)
Fair value of plan assets, ending balance	87	81	87
Funded status	(10)	(20)
Amounts recognized in the Consolidated Balance Sheets consist of:
Other assets	32	31
Other liabilities	(42)	(51)
Net amount recognized	$ (10)	$ (20)