Employee Benefits - Fair Values of Postretirement Plan Assets by Asset Category (Detail) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
United States Postretirement Benefit Plan of US Entity [Member] | Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	$ 23	$ 18
United States Postretirement Benefit Plan of US Entity [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	5	4
United States Postretirement Benefit Plan of US Entity [Member] | Investment Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	10	16
Foreign Postretirement Benefit Plan [Member] | Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	5	4
Foreign Postretirement Benefit Plan [Member] | Investment Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value		4
Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	50	49	$ 56
Other Postretirement Benefit Plans [Member] | Short-term investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	7	1
Other Postretirement Benefit Plans [Member] | Convertible Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value		2
Level 1 [Member] | United States Postretirement Benefit Plan of US Entity [Member] | Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	23	18
Level 1 [Member] | United States Postretirement Benefit Plan of US Entity [Member] | Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	5	4
Level 1 [Member] | Foreign Postretirement Benefit Plan [Member] | Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	5	4
Level 1 [Member] | Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	33	26
Level 2 [Member] | United States Postretirement Benefit Plan of US Entity [Member] | Investment Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	10	16
Level 2 [Member] | Foreign Postretirement Benefit Plan [Member] | Investment Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value		4
Level 2 [Member] | Other Postretirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	17	23
Level 2 [Member] | Other Postretirement Benefit Plans [Member] | Short-term investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value	$ 7	1
Level 2 [Member] | Other Postretirement Benefit Plans [Member] | Convertible Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Assets at fair value		$ 2