Employee Benefits - Other Pre-tax Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive (Income) Loss (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Pension
Reversal of amortization items
Prior service cost (benefit)	$ (112)	$ (112)	$ (82)
Total recognized in Other comprehensive loss (income) (pre-tax)	(112)	(112)	(82)
Health Care and Life
Reversal of amortization items
Prior service cost (benefit)	129	419	530
Total recognized in Other comprehensive loss (income) (pre-tax)	$ 129	$ 419	$ 530