Investment Securities (Investments Classified by Contractual Maturity Date) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Amount
Total available-for-sale securities	$ 26,794	$ 29,541
Due in one year or less	219	125
Due after one year through five years	2,770	2,229
Due after five years through ten years	3,016	3,476
Due after ten years	$ 20,789	$ 23,711
Yield
Total	2.50%	2.50%
Due in one year or less	2.20%	2.30%
Due after one year through five years	1.90%	1.90%
Due after five years through ten years	2.40%	2.10%
Due after ten years	2.60%	2.60%
Amortized cost of available-for-sale securities
Total	$ 33,265	$ 34,863
Due in one year or less	224	126
Due after one year through five years	3,033	2,403
Due after five years through ten years	3,662	4,048
Due after ten years	26,346	28,286
Amount
Total	1,013	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	$ 1,013	$ 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%
Cash equivalents	$ 58	$ 18
U.S. Treasury and federal agencies
Amount
Total available-for-sale securities	1,991	2,016
Due in one year or less	23	0
Due after one year through five years	1,270	716
Due after five years through ten years	698	1,300
Due after ten years	$ 0	$ 0
Yield
Total	1.60%	1.60%
Due in one year or less	2.00%	0.00%
Due after one year through five years	1.40%	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	$ 2,280	$ 2,272
U.S. States and political subdivisions
Amount
Total available-for-sale securities	612	760
Due in one year or less	5	26
Due after one year through five years	44	60
Due after five years through ten years	112	112
Due after ten years	$ 451	$ 562
Yield
Total	3.20%	3.20%
Due in one year or less	2.20%	2.70%
Due after one year through five years	2.40%	2.70%
Due after five years through ten years	3.60%	3.30%
Due after ten years	3.20%	3.20%
Amortized cost of available-for-sale securities
Total	$ 729	$ 841
Foreign government
Amount
Total available-for-sale securities	159	146
Due in one year or less	19	13
Due after one year through five years	72	74
Due after five years through ten years	68	59
Due after ten years	$ 0	$ 0
Yield
Total	2.00%	1.80%
Due in one year or less	1.40%	0.80%
Due after one year through five years	2.10%	1.80%
Due after five years through ten years	2.20%	1.90%
Due after ten years	0.00%	0.00%
Amortized cost of available-for-sale securities
Total	$ 175	$ 158
Agency mortgage-backed security
Amount
Total available-for-sale securities	14,636	16,633
Due in one year or less	0	0
Due after one year through five years	11	0
Due after five years through ten years	33	27
Due after ten years	$ 14,592	$ 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	$ 18,434	$ 19,668
Amount
Total	1,013	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	$ 1,013	$ 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 liability, fair value hedge, cumulative increase (decrease)	$ 148	$ 12
Mortgage-backed residential
Amount
Total available-for-sale securities	3,873	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	12	14
Due after ten years	$ 3,861	$ 4,285
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	2.90%	2.90%
Due after ten years	2.80%	2.80%
Amortized cost of available-for-sale securities
Total	$ 4,858	$ 5,154
Agency mortgage-backed commercial
Amount
Total available-for-sale securities	3,466	3,535
Due in one year or less	0	0
Due after one year through five years	116	66
Due after five years through ten years	1,474	1,234
Due after ten years	$ 1,876	$ 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	3.30%	3.10%
Due after five years through ten years	2.30%	2.10%
Due after ten years	2.10%	2.10%
Amortized cost of available-for-sale securities
Total	$ 4,497	$ 4,380
Yield
Hedged liability, fair value hedge, cumulative increase (decrease)	86
Hedged asset, fair value hedge, cumulative increase (decrease)		15
Asset-backed
Amount
Total available-for-sale securities	354	433
Due in one year or less	0	0
Due after one year through five years	349	401
Due after five years through ten years	5	25
Due after ten years	$ 0	$ 7
Yield
Total	1.80%	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	0.00%	3.50%
Amortized cost of available-for-sale securities
Total	$ 370	$ 459
Corporate debt
Amount
Total available-for-sale securities	1,703	1,719
Due in one year or less	172	86
Due after one year through five years	908	912
Due after five years through ten years	614	705
Due after ten years	$ 9	$ 16
Yield
Total	2.60%	2.40%
Due in one year or less	2.30%	2.40%
Due after one year through five years	2.60%	2.30%
Due after five years through ten years	2.70%	2.60%
Due after ten years	5.80%	4.90%
Amortized cost of available-for-sale securities
Total	$ 1,922	$ 1,931