Investment Securities (Investments Classified by Contractual Maturity Date) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Amount
Total available-for-sale securities	$ 24,415	$ 29,541
Due in one year or less	449	125
Due after one year through five years	2,672	2,229
Due after five years through ten years	3,279	3,476
Due after ten years	$ 18,015	$ 23,711
Yield
Total	2.50%	2.50%
Due in one year or less	1.70%	2.30%
Due after one year through five years	2.10%	1.90%
Due after five years through ten years	2.40%	2.10%
Due after ten years	2.50%	2.60%
Amortized cost of available-for-sale securities
Total	$ 28,416	$ 34,863
Due in one year or less	461	126
Due after one year through five years	2,844	2,403
Due after five years through ten years	3,746	4,048
Due after ten years	21,365	28,286
Amount
Total	4,680	1,062
Due in one year or less	1	0
Due after one year through five years	41	0
Due after five years through ten years	14	0
Due after ten years	$ 4,624	$ 1,062
Yield
Total	2.80%	2.80%
Due in one year or less	5.60%	0.00%
Due after one year through five years	5.60%	0.00%
Due after five years through ten years	3.40%	0.00%
Due after ten years	2.80%	2.80%
Cash equivalents	$ 36	$ 18
U.S. Treasury and federal agencies
Amount
Total available-for-sale securities	2,075	2,016
Due in one year or less	215	0
Due after one year through five years	1,120	716
Due after five years through ten years	740	1,300
Due after ten years	$ 0	$ 0
Yield
Total	1.60%	1.60%
Due in one year or less	0.90%	0.00%
Due after one year through five years	1.50%	1.30%
Due after five years through ten years	1.90%	1.70%
Due after ten years	0.00%	0.00%
Amortized cost of available-for-sale securities
Total	$ 2,284	$ 2,272
U.S. States and political subdivisions
Amount
Total available-for-sale securities	658	760
Due in one year or less	4	26
Due after one year through five years	55	60
Due after five years through ten years	110	112
Due after ten years	$ 489	$ 562
Yield
Total	3.20%	3.20%
Due in one year or less	3.40%	2.70%
Due after one year through five years	2.70%	2.70%
Due after five years through ten years	3.60%	3.30%
Due after ten years	3.10%	3.20%
Amortized cost of available-for-sale securities
Total	$ 727	$ 841
Foreign government
Amount
Total available-for-sale securities	183	146
Due in one year or less	20	13
Due after one year through five years	82	74
Due after five years through ten years	81	59
Due after ten years	$ 0	$ 0
Yield
Total	2.30%	1.80%
Due in one year or less	1.30%	0.80%
Due after one year through five years	2.40%	1.80%
Due after five years through ten years	2.50%	1.90%
Due after ten years	0.00%	0.00%
Amortized cost of available-for-sale securities
Total	$ 190	$ 158
Agency mortgage-backed residential
Amount
Total available-for-sale securities	15,384	16,633
Due in one year or less	0	0
Due after one year through five years	10	0
Due after five years through ten years	32	27
Due after ten years	$ 15,342	$ 16,606
Yield
Total	2.60%	2.60%
Due in one year or less	0.00%	0.00%
Due after one year through five years	1.90%	0.00%
Due after five years through ten years	2.50%	2.00%
Due after ten years	2.60%	2.60%
Amortized cost of available-for-sale securities
Total	$ 18,122	$ 19,668
Amount
Total	999	1,062
Due in one year or less	0	0
Due after one year through five years	0	0
Due after five years through ten years	0	0
Due after ten years	$ 999	$ 1,062
Yield
Total	2.80%	2.80%
Due in one year or less	0.00%	0.00%
Due after one year through five years	0.00%	0.00%
Due after five years through ten years	0.00%	0.00%
Due after ten years	2.80%	2.80%
Hedged asset, fair value hedge, cumulative increase (decrease)	$ 46
Hedged liability, fair value hedge, cumulative increase (decrease)		$ 12
Mortgage-backed residential
Amount
Total available-for-sale securities	225	4,299
Due in one year or less	0	0
Due after one year through five years	0	0
Due after five years through ten years	0	14
Due after ten years	$ 225	$ 4,285
Yield
Total	2.70%	2.80%
Due in one year or less	0.00%	0.00%
Due after one year through five years	0.00%	0.00%
Due after five years through ten years	0.00%	2.90%
Due after ten years	2.70%	2.80%
Amortized cost of available-for-sale securities
Total	$ 268	$ 5,154
Amount
Total	3,603	0
Due in one year or less	0
Due after one year through five years	0
Due after five years through ten years	12
Due after ten years	$ 3,591
Yield
Total	2.80%
Due in one year or less	0.00%
Due after one year through five years	0.00%
Due after five years through ten years	3.00%
Due after ten years	2.80%
Agency mortgage-backed commercial
Amount
Total available-for-sale securities	$ 3,758	3,535
Due in one year or less	0	0
Due after one year through five years	163	66
Due after five years through ten years	1,641	1,234
Due after ten years	$ 1,954	$ 2,235
Yield
Total	2.30%	2.20%
Due in one year or less	0.00%	0.00%
Due after one year through five years	3.80%	3.10%
Due after five years through ten years	2.40%	2.10%
Due after ten years	2.10%	2.10%
Amortized cost of available-for-sale securities
Total	$ 4,539	$ 4,380
Yield
Hedged asset, fair value hedge, cumulative increase (decrease)	29	15
Asset-backed
Amount
Total available-for-sale securities	332	433
Due in one year or less	0	0
Due after one year through five years	327	401
Due after five years through ten years	4	25
Due after ten years	$ 1	$ 7
Yield
Total	1.70%	1.70%
Due in one year or less	0.00%	0.00%
Due after one year through five years	1.70%	1.70%
Due after five years through ten years	3.90%	1.80%
Due after ten years	2.70%	3.50%
Amortized cost of available-for-sale securities
Total	$ 344	$ 459
Amount
Total	78	0
Due in one year or less	1
Due after one year through five years	41
Due after five years through ten years	2
Due after ten years	$ 34
Yield
Total	5.60%
Due in one year or less	5.60%
Due after one year through five years	5.60%
Due after five years through ten years	6.00%
Due after ten years	5.60%
Corporate debt
Amount
Total available-for-sale securities	$ 1,800	1,719
Due in one year or less	210	86
Due after one year through five years	915	912
Due after five years through ten years	671	705
Due after ten years	$ 4	$ 16
Yield
Total	2.70%	2.40%
Due in one year or less	2.40%	2.40%
Due after one year through five years	2.60%	2.30%
Due after five years through ten years	2.90%	2.60%
Due after ten years	6.20%	4.90%
Amortized cost of available-for-sale securities
Total	$ 1,942	$ 1,931