Investment Securities (Schedule of Unrealized Loss on Investments) (Details) - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Less than 12 months
Fair value	$ 1,008,000,000	$ 12,548,000,000
Unrealized loss	(53,000,000)	(1,503,000,000)
12 months or longer
Fair value	25,706,000,000	16,660,000,000
Unrealized loss	(6,418,000,000)	(3,824,000,000)
Credit reserves	0	0
U.S. Treasury and federal agencies
Less than 12 months
Fair value	0	529,000,000
Unrealized loss	0	(68,000,000)
12 months or longer
Fair value	1,991,000,000	1,487,000,000
Unrealized loss	(289,000,000)	(188,000,000)
U.S. States and political subdivisions
Less than 12 months
Fair value	139,000,000	547,000,000
Unrealized loss	(6,000,000)	(55,000,000)
12 months or longer
Fair value	465,000,000	135,000,000
Unrealized loss	(111,000,000)	(27,000,000)
Foreign government
Less than 12 months
Fair value	25,000,000	75,000,000
Unrealized loss	(2,000,000)	(4,000,000)
12 months or longer
Fair value	135,000,000	71,000,000
Unrealized loss	(14,000,000)	(8,000,000)
Agency mortgage-backed security
Less than 12 months
Fair value	356,000,000	7,472,000,000
Unrealized loss	(23,000,000)	(892,000,000)
12 months or longer
Fair value	14,280,000,000	8,978,000,000
Unrealized loss	(3,775,000,000)	(2,146,000,000)
Mortgage-backed residential
Less than 12 months
Fair value	151,000,000	1,985,000,000
Unrealized loss	(6,000,000)	(289,000,000)
12 months or longer
Fair value	3,716,000,000	2,287,000,000
Unrealized loss	(979,000,000)	(566,000,000)
Agency mortgage-backed commercial
Less than 12 months
Fair value	172,000,000	996,000,000
Unrealized loss	(10,000,000)	(124,000,000)
12 months or longer
Fair value	3,247,000,000	2,535,000,000
Unrealized loss	(1,021,000,000)	(721,000,000)
Asset-backed
Less than 12 months
Fair value	18,000,000	162,000,000
Unrealized loss	0	(4,000,000)
12 months or longer
Fair value	322,000,000	272,000,000
Unrealized loss	(16,000,000)	(22,000,000)
Corporate debt
Less than 12 months
Fair value	147,000,000	782,000,000
Unrealized loss	(6,000,000)	(67,000,000)
12 months or longer
Fair value	1,550,000,000	895,000,000
Unrealized loss	$ (213,000,000)	$ (146,000,000)