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, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss arising during the year	$ 60
New prior service credit	(17)
Amortization of actuarial loss	8	$ 19	$ 12
Amortization of prior service credit	57	60	59
Foreign currency translation adjustments	1
Impact of settlements and curtailments	0
Net change	93
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss arising during the year	179
New prior service credit	0
Amortization of actuarial loss	62	$ 63	$ 75
Amortization of prior service credit	0
Foreign currency translation adjustments	5
Impact of settlements and curtailments	(2)
Net change	$ 120