Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 1,353	$ 1,425	$ 3,907	$ 3,947
Net actuarial losses of defined benefit plans:
Adjustments, net of tax effect of $3 and ($2); $4 and $1	(7)	5	(8)	0
Recognized within net income, net of tax effect of ($2) and ($3); ($7) and ($10)	7	9	21	30
Prior service credit of defined benefit plans:
Recognized within net income, net of tax effect of $0 and $0; $0 and $0	(1)	0	(1)	0
Other comprehensive income (loss), net of taxes	(1)	14	12	30
Total comprehensive income	$ 1,352	$ 1,439	$ 3,919	$ 3,977