Consolidated Statement of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Net income	$ 404	$ 454	$ 1,365	$ 2,023
Other comprehensive income (loss):
Changes in net unrealized gains (losses) on investment securities having no credit losses recognized in the consolidated statement of income	(2,391)	(3,204)	(1,986)	(11,078)
Changes in net unrealized gains (losses) on investment securities having credit losses recognized in the consolidated statement of income	0	0	0	(3)
Net changes in benefit plan assets and obligations	(3)	12	(10)	34
Net changes in unrealized foreign currency translation	(118)	(251)	13	(423)
Other comprehensive loss before income taxes	(2,512)	(3,443)	(1,983)	(11,470)
Income tax benefit	(509)	(690)	(416)	(2,369)
Other comprehensive loss, net of taxes	(2,003)	(2,753)	(1,567)	(9,101)
Comprehensive loss	$ (1,599)	$ (2,299)	$ (202)	$ (7,078)