Consolidated Statement of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 934	$ (40)	$ 1,667	$ 560
Other comprehensive income (loss)
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income (loss)	533	2,359	(1,063)	1,784
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income (loss)	0	3	0	(3)
Net changes in benefit plan assets and obligations	26	21	51	44
Net changes in unrealized foreign currency translation	40	52	66	(216)
Other comprehensive income (loss) before income taxes	599	2,435	(946)	1,609
Income tax expense (benefit)	121	504	(213)	367
Other comprehensive income (loss), net of taxes	478	1,931	(733)	1,242
Comprehensive income	$ 1,412	$ 1,891	$ 934	$ 1,802