Consolidated Statement of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 3,662	$ 2,697	$ 2,622
Other comprehensive income (loss):
Changes in net unrealized gains (losses) on investment securities having no credit losses recognized in the consolidated statement of income	(2,115)	2,331	2,994
Changes in net unrealized gains (losses) on investment securities having credit losses recognized in the consolidated statement of income	0	(9)	(4)
Net changes in benefit plan assets and obligations	455	18	33
Net changes in unrealized foreign currency translation	(11)	12	117
Other comprehensive income (loss) before income taxes	(1,671)	2,352	3,140
Income tax expense (benefit)	(362)	490	641
Other comprehensive income (loss), net of taxes	(1,309)	1,862	2,499
Comprehensive income	$ 2,353	$ 4,559	$ 5,121