Employee Benefits - Additional Information (Detail) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Amount paid in severance benefits over the period	$ 52,000,000			$ 175,000,000
Post employment benefits liability	443,000,000			443,000,000
Pension
Defined Benefit Plan Disclosure [Line Items]
Remeasurement loss, net	(153,000,000)	$ (182,000,000)	$ 0	(335,000,000)	$ 96,000,000
(Charge) credit due to difference between estimated and actual return on assets	$ (163,000,000)				(150,000,000)
(Credit) charge due to change in discount rate assumption		$ 196,000,000			54,000,000
Pension | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Employer discretionary contribution amount				$ 0	$ 300,000,000