Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 1,305	$ 1,405	$ 2,522	$ 2,771
Net actuarial losses of defined benefit plans:
Adjustments	(3)	15	(5)	(1)
Recognized within net income	11	9	21	18
Prior service credit of defined benefit plans:
Recognized within net income	0	(1)	0	(2)
Derivative instruments:
Change in fair value	0	(2)	0	(2)
Other comprehensive income (loss)	8	21	16	13
Total comprehensive income	$ 1,313	$ 1,426	$ 2,538	$ 2,784