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, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain) arising during the year	$ 8
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain) arising during the year	(47)
New prior service cost	1
Amortization of actuarial loss	19	$ 12	$ 19
Amortization of prior service credit	60	59	31
Foreign currency translation adjustments	(1)
Impact of settlements and curtailments	0
Net change	(6)
United States
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain) arising during the year	39
New prior service cost	2
Amortization of actuarial loss	63	$ 75	110
Amortization of prior service credit	0		$ 1
Foreign currency translation adjustments	(10)
Impact of settlements and curtailments	(1)
Net change	$ (33)