Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 828	$ 839	$ 2,511	$ 2,452
OCI, net of tax:
Change in unrecognized net pension and postretirement costs	(38)	(12)	(2)	15
Change in unrealized net gains (losses) on cash flow hedges	13	20	(80)	124
Change in unrealized net gains (losses) on AFS securities	118	(155)	769	(522)
Other, net	0	1	2	(2)
Total OCI	93	(146)	689	(385)
Total comprehensive income	921	693	3,200	2,067
Income Tax Effect of Items Included in OCI:
Change in unrecognized net pension and postretirement costs	(11)	(5)	0	4
Change in unrealized net gains (losses) on cash flow hedges	4	6	(25)	40
Change in unrealized net gains (losses) on AFS securities	37	(48)	237	(163)
Other, net	$ (1)	$ 0	$ 0	$ 1