Consolidated Statement of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 551	$ 934	$ 1,569	$ 1,667
Other comprehensive income (loss)
Changes in net unrealized gains (losses) on investment securities having no credit losses recognized in the consolidated statement of income	(3,045)	533	(7,874)	(1,063)
Changes in net unrealized gains (losses) on investment securities having credit losses recognized in the consolidated statement of income	(2)	0	(3)	0
Net changes in benefit plan assets and obligations	11	26	22	51
Net changes in unrealized foreign currency translation	(174)	40	(172)	66
Other comprehensive income (loss) before income taxes	(3,210)	599	(8,027)	(946)
Income tax expense (benefit)	(657)	121	(1,679)	(213)
Other comprehensive income (loss), net of taxes	(2,553)	478	(6,348)	(733)
Comprehensive income (loss)	$ (2,002)	$ 1,412	$ (4,779)	$ 934