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	$ 885	$ 822	$ 1,683	$ 1,613
OCI, net of tax:
Change in unrecognized net pension and postretirement costs	19	13	36	27
Change in unrealized net gains (losses) on cash flow hedges	(59)	26	(93)	104
Change in unrealized net gains (losses) on AFS securities	342	(99)	651	(367)
Other, net	0	(1)	2	(3)
Total OCI	302	(61)	596	(239)
Total comprehensive income	1,187	761	2,279	1,374
Income Tax Effect of Items Included in OCI:
Change in unrecognized net pension and postretirement costs	5	5	11	9
Change in unrealized net gains (losses) on cash flow hedges	(18)	8	(29)	34
Change in unrealized net gains (losses) on AFS securities	105	(31)	200	(115)
Other, net	$ 1	$ 0	$ 1	$ 1