Investment Securities (Contractual Maturity of Securities) (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Total securities available for sale at amortized cost
1 Year or Less	$ 956
After 1 Year through 5 Years	12,477
After 5 Years through 10 Years	15,944
After 10 Years	33,273
Total	62,650	$ 45,353
Available-for-sale, fair value
1 Year or Less	953
After 1 Year through 5 Years	12,432
After 5 Years through 10 Years	15,760
After 10 Years	31,193
Total	$ 60,338	41,785
Weighted-average yield, GAAP basis, available for sale securities	3.73%
Total securities held to maturity at amortized cost
1 Year or Less	$ 10,743
After 1 Year through 5 Years	23,050
After 5 Years through 10 Years	4,604
After 10 Years	45,448
Total	83,845	90,784
Held-to-maturity, fair value
1 Year or Less	10,690
After 1 Year through 5 Years	22,663
After 5 Years through 10 Years	4,532
After 10 Years	43,513
Total	$ 81,398	86,948
Weighted-average yield, GAAP basis, held to maturity securities	2.37%
1 Year or Less
Available-for-sale, fair value
Weighted-average yield, GAAP basis, available for sale securities	3.34%
Held-to-maturity, fair value
Weighted-average yield, GAAP basis, held to maturity securities	1.30%
After 1 Year through 5 Years
Available-for-sale, fair value
Weighted-average yield, GAAP basis, available for sale securities	3.61%
Held-to-maturity, fair value
Weighted-average yield, GAAP basis, held to maturity securities	1.51%
After 5 Years through 10 Years
Available-for-sale, fair value
Weighted-average yield, GAAP basis, available for sale securities	4.15%
Held-to-maturity, fair value
Weighted-average yield, GAAP basis, held to maturity securities	3.51%
After 10 Years
Available-for-sale, fair value
Weighted-average yield, GAAP basis, available for sale securities	3.59%
Held-to-maturity, fair value
Weighted-average yield, GAAP basis, held to maturity securities	2.95%
U.S. Treasury and government agencies
Total securities available for sale at amortized cost
1 Year or Less	$ 507
After 1 Year through 5 Years	8,700
After 5 Years through 10 Years	11,291
After 10 Years	2,457
Total	22,955	7,596
Available-for-sale, fair value
Total	22,639	6,951
Total securities held to maturity at amortized cost
1 Year or Less	10,401
After 1 Year through 5 Years	20,906
After 5 Years through 10 Years	1,640
After 10 Years	877
Total	33,824	36,529
Held-to-maturity, fair value
Total	33,246	35,397
Residential mortgage-backed | Mortgage-backed Securities Agency
Total securities available for sale at amortized cost
1 Year or Less	1
After 1 Year through 5 Years	218
After 5 Years through 10 Years	3,323
After 10 Years	28,124
Total	31,666
Total securities held to maturity at amortized cost
After 1 Year through 5 Years	8
After 5 Years through 10 Years	295
After 10 Years	40,680
Total	40,983
Residential mortgage-backed | Mortgage-backed Securities Non-agency
Total securities available for sale at amortized cost
After 5 Years through 10 Years	17
After 10 Years	500
Total	517
Total securities held to maturity at amortized cost
After 10 Years	245
Total	245
Commercial mortgage servicing rights | Mortgage-backed Securities Agency
Total securities available for sale at amortized cost
1 Year or Less	72
After 1 Year through 5 Years	953
After 5 Years through 10 Years	626
After 10 Years	329
Total	1,980
Total securities held to maturity at amortized cost
After 1 Year through 5 Years	180
After 5 Years through 10 Years	582
After 10 Years	210
Total	972
Commercial mortgage servicing rights | Mortgage-backed Securities Non-agency
Total securities available for sale at amortized cost
1 Year or Less	1
After 1 Year through 5 Years	103
After 5 Years through 10 Years	86
After 10 Years	562
Total	752
Total securities held to maturity at amortized cost
1 Year or Less
After 1 Year through 5 Years	46
After 10 Years	960
Total	1,006
Asset-backed
Total securities available for sale at amortized cost
After 1 Year through 5 Years	750
After 5 Years through 10 Years	318
After 10 Years	1,161
Total	2,229
Total securities held to maturity at amortized cost
1 Year or Less	17
After 1 Year through 5 Years	1,081
After 5 Years through 10 Years	1,716
After 10 Years	1,192
Total	4,006
Other
Total securities available for sale at amortized cost
1 Year or Less	375
After 1 Year through 5 Years	1,753
After 5 Years through 10 Years	283
After 10 Years	140
Total	2,551	2,844
Available-for-sale, fair value
Total	2,495	2,727
Total securities held to maturity at amortized cost
1 Year or Less	325
After 1 Year through 5 Years	829
After 5 Years through 10 Years	371
After 10 Years	1,284
Total	2,809	3,108
Held-to-maturity, fair value
Total	$ 2,829	$ 3,123