AFS and HTM Debt Securities, Outstanding (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Available-for-sale debt securities:
Available-for-sale, at amortized cost, net	$ 124,906	$ 175,463
Available-for-sale, gross unrealized gains	106	2,635
Available-for-sale, gross unrealized losses	(9,177)	(854)
Available-for-sale, at fair value	115,835	177,244
Held-to-maturity debt securities:
Held-to-maturity, amortized cost, net	300,434	272,022
Held-to-maturity, gross unrealized gains	4	3,570
Held-to-maturity, gross unrealized losses	(44,867)	(3,206)
Held-to-maturity, at fair value	255,571	272,386
Total AFS and HTM Debt securities:
Amortized cost, net	425,340	447,485
Debt securities, gross unrealized gains	110	6,205
Debt securities, gross unrealized losses	(54,044)	(4,060)
Fair value	371,406	449,630
Allowance for credit loss, available-for-sale debt securities	6	8
Allowance for credit loss, held-to-maturity debt securities	96	96
Securities of U.S. Treasury and federal agencies [Member]
Available-for-sale debt securities:
Available-for-sale, at amortized cost, net	47,102	39,668
Available-for-sale, gross unrealized gains	3	185
Available-for-sale, gross unrealized losses	(2,375)	(192)
Available-for-sale, at fair value	44,730	39,661
Held-to-maturity debt securities:
Held-to-maturity, amortized cost, net	16,200	16,544
Held-to-maturity, gross unrealized gains	0	599
Held-to-maturity, gross unrealized losses	(1,842)	(318)
Held-to-maturity, at fair value	14,358	16,825
Non-U.S. government securities [Member]
Available-for-sale debt securities:
Available-for-sale, at amortized cost, net	162	71
Available-for-sale, gross unrealized gains	0	0
Available-for-sale, gross unrealized losses	0	0
Available-for-sale, at fair value	162	71
Securities of U.S. states and political subdivisions [Member]
Available-for-sale debt securities:
Available-for-sale, at amortized cost, net	11,218	16,618
Available-for-sale, gross unrealized gains	17	350
Available-for-sale, gross unrealized losses	(569)	(51)
Available-for-sale, at fair value	10,666	16,917
Held-to-maturity debt securities:
Held-to-maturity, amortized cost, net	31,478	32,689
Held-to-maturity, gross unrealized gains	2	847
Held-to-maturity, gross unrealized losses	(5,563)	(61)
Held-to-maturity, at fair value	25,917	33,475
Securities of U.S. states and political subdivisions [Member] | Nontaxable preferred debt securities [Member]
Available-for-sale debt securities:
Available-for-sale, at amortized cost, net	5,400	5,200
Available-for-sale, at fair value	5,400	5,200
Federal agency mortgage-backed securities [Member]
Available-for-sale debt securities:
Available-for-sale, at amortized cost, net	56,283	104,661
Available-for-sale, gross unrealized gains	3	1,807
Available-for-sale, gross unrealized losses	(5,935)	(582)
Available-for-sale, at fair value	50,351	105,886
Held-to-maturity debt securities:
Held-to-maturity, amortized cost, net	219,739	188,909
Held-to-maturity, gross unrealized gains	0	1,882
Held-to-maturity, gross unrealized losses	(36,034)	(2,807)
Held-to-maturity, at fair value	183,705	187,984
Non-agency mortgage-backed securities [Member]
Available-for-sale debt securities:
Available-for-sale, at amortized cost, net	3,546	4,515
Available-for-sale, gross unrealized gains	1	32
Available-for-sale, gross unrealized losses	(121)	(15)
Available-for-sale, at fair value	3,426	4,532
Held-to-maturity debt securities:
Held-to-maturity, amortized cost, net	1,243	1,082
Held-to-maturity, gross unrealized gains	1	31
Held-to-maturity, gross unrealized losses	(174)	(18)
Held-to-maturity, at fair value	1,070	1,095
Collateralized loan obligations [Member]
Available-for-sale debt securities:
Available-for-sale, at amortized cost, net	4,270	5,713
Available-for-sale, gross unrealized gains	0	2
Available-for-sale, gross unrealized losses	(136)	(7)
Available-for-sale, at fair value	4,134	5,708
Held-to-maturity debt securities:
Held-to-maturity, amortized cost, net	30,046	31,067
Held-to-maturity, gross unrealized gains	1	194
Held-to-maturity, gross unrealized losses	(1,089)	(2)
Held-to-maturity, at fair value	28,958	31,259
Other debt securities [Member]
Available-for-sale debt securities:
Available-for-sale, at amortized cost, net	2,325	4,217
Available-for-sale, gross unrealized gains	82	259
Available-for-sale, gross unrealized losses	(41)	(7)
Available-for-sale, at fair value	2,366	4,469
Held-to-maturity debt securities:
Held-to-maturity, amortized cost, net	1,728	1,731
Held-to-maturity, gross unrealized gains	0	17
Held-to-maturity, gross unrealized losses	(165)	0
Held-to-maturity, at fair value	$ 1,563	$ 1,748