Investment Securities (Schedule of Unrealized Loss on Investments) (Details) - USD ($)	Mar. 31, 2023	Dec. 31, 2022
Less than 12 months
Fair value	$ 3,519,000,000	$ 12,548,000,000
Unrealized loss	(160,000,000)	(1,503,000,000)
12 months or longer
Fair value	25,577,000,000	16,660,000,000
Unrealized loss	(4,666,000,000)	(3,824,000,000)
Credit reserves	0	0
U.S. Treasury and federal agencies
Less than 12 months
Fair value	10,000,000	529,000,000
Unrealized loss	0	(68,000,000)
12 months or longer
Fair value	2,054,000,000	1,487,000,000
Unrealized loss	(210,000,000)	(188,000,000)
U.S. States and political subdivisions
Less than 12 months
Fair value	164,000,000	547,000,000
Unrealized loss	(2,000,000)	(55,000,000)
12 months or longer
Fair value	439,000,000	135,000,000
Unrealized loss	(70,000,000)	(27,000,000)
Foreign government
Less than 12 months
Fair value	16,000,000	75,000,000
Unrealized loss	0	(4,000,000)
12 months or longer
Fair value	137,000,000	71,000,000
Unrealized loss	(9,000,000)	(8,000,000)
Agency mortgage-backed security
Less than 12 months
Fair value	1,998,000,000	7,472,000,000
Unrealized loss	(95,000,000)	(892,000,000)
12 months or longer
Fair value	14,364,000,000	8,978,000,000
Unrealized loss	(2,646,000,000)	(2,146,000,000)
Mortgage-backed residential
Less than 12 months
Fair value	512,000,000	1,985,000,000
Unrealized loss	(29,000,000)	(289,000,000)
12 months or longer
Fair value	3,726,000,000	2,287,000,000
Unrealized loss	(759,000,000)	(566,000,000)
Agency mortgage-backed commercial
Less than 12 months
Fair value	507,000,000	996,000,000
Unrealized loss	(24,000,000)	(124,000,000)
12 months or longer
Fair value	3,089,000,000	2,535,000,000
Unrealized loss	(775,000,000)	(721,000,000)
Asset-backed
Less than 12 months
Fair value	50,000,000	162,000,000
Unrealized loss	(1,000,000)	(4,000,000)
12 months or longer
Fair value	362,000,000	272,000,000
Unrealized loss	(20,000,000)	(22,000,000)
Corporate debt
Less than 12 months
Fair value	262,000,000	782,000,000
Unrealized loss	(9,000,000)	(67,000,000)
12 months or longer
Fair value	1,406,000,000	895,000,000
Unrealized loss	$ (177,000,000)	$ (146,000,000)