Employee Benefit Plans (Change in Accumulated Other Comprehensive Loss (Pretax) Relating to Defined Benefit Pension and Other Postretirement Benefits) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain) arising during the year	$ 3
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain) arising during the year	(35)
New prior service cost (credit)	1
Amortization of actuarial loss	(12)
Amortization of prior service (cost) credit	59
Foreign currency translation adjustments	0
Impact of settlements and curtailments	0
Net change	13
Pensions
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain) arising during the year	38
New prior service cost (credit)	(2)
Amortization of actuarial loss	(75)
Amortization of prior service (cost) credit	(1)
Foreign currency translation adjustments	19
Impact of settlements and curtailments	(63)
Net change	$ (84)
Pensions | Pensions
Defined Benefit Plan Disclosure [Line Items]
Amortization of prior service (cost) credit		$ (1)	$ (2)