Employee Benefit Plans (Net Periodic Benefit Costs) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 12	$ 10	$ 8
Interest cost	14	20	26
Amortization of prior service credit	(54)	(59)	(57)
Amortization of actuarial losses	20	15	8
Net periodic benefit cost/(income)	(8)	(14)	(15)
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	9	24	23
Interest cost	65	87	105
Expected return on plan assets	152	144	139
Amortization of prior service credit	0
Amortization of actuarial losses	39	71	62
Settlements, curtailments, and special termination benefits	53	18	3
Net periodic benefit cost/(income)	$ 14	$ 56	$ 54