Accumulated Other Comprehensive Income (Components of Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Before Tax
Net unrealized gain (loss)	$ (1,519)	$ 97	$ (5,420)	$ 7,361
Other reclassifications included in other revenue	0	(3)	(14)	(3)
Other	0	0	0	1
Other comprehensive income (loss), before tax	(1,519)	94	(5,434)	7,359
Tax Effect
Net unrealized gain (loss)	364	(20)	1,289	(1,762)
Other reclassifications included in other revenue	0	1	4	1
Other			0	0
Other comprehensive income (loss)	364	(19)	1,293	(1,761)
Net of Tax
Net unrealized gain (loss)	(1,155)	77	(4,131)	5,599
Other reclassifications included in other revenue	0	(2)	(10)	(2)
Other			0	1
Other comprehensive income (loss), net of tax	$ (1,155)	$ 75	$ (4,141)	$ 5,598