Consolidated Statement of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 1,018	$ 733
Other comprehensive loss
Changes in net unrealized gains (losses) on investment securities having no credit losses recognized in the consolidated statement of income	(4,829)	(1,596)
Changes in net unrealized gains (losses) on investment securities having credit losses recognized in the consolidated statement of income	(1)	0
Net changes in benefit plan assets and obligations	11	25
Net changes in unrealized foreign currency translation	2	26
Other comprehensive loss before income taxes	(4,817)	(1,545)
Income tax benefit	(1,022)	(334)
Other comprehensive loss, net of taxes	(3,795)	(1,211)
Comprehensive loss	$ (2,777)	$ (478)