Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 6,510	$ 8,749	$ 7,769
Net actuarial losses of defined benefit plans:
Adjustments, net of tax effect of ($9), $48 and ($56)	27	(155)	175
Recognized within net income, net of tax effect of ($5), ($17) and ($8)	15	61	29
Prior service cost (credit) of defined benefit plans:
Recognized within net income, net of tax effect of $0, $0 and $0	1	(1)	(1)
Derivative instruments:
Change in fair value, net of tax effect of $0, $0 and $0	1	1	0
Available-for-sale investments:
Unrealized gains (losses), net of tax effect of ($1), $1 and $0	5	(3)	0
Other comprehensive income (loss), net of taxes	49	(97)	203
Total comprehensive income	$ 6,559	$ 8,652	$ 7,972