Securities - Amortized Cost, Gross Unrealized Gains and Losses and Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Available-for-sale:
Amortized cost	$ 95,627	$ 100,774
Gross unrealized, Gain	487	1,859
Gross unrealized, Loss	4,836	794
Available-for-sale, amount	91,278	101,839
Held-to-maturity:
Amortized cost	59,566	56,866
Gross unrealized, Gains	18	526
Gross unrealized, Losses	4,457	617
Securities held-to-maturity	55,127	56,775
Amortized cost, Total	155,193	157,640
Gross unrealized, Gain, Total	505	2,385
Gross unrealized, Losses, Total	9,293	1,411
Fair value, Total	146,405	158,614
Debt securities, available-for-sale, allowance for credit loss	9	10
Debt securities, held-to-maturity, allowance for credit loss	1	1
Debt securities, available-for-sale and held-to-maturity, allowance for credit loss	10	10
AOCI, transfers from AFS to HTM Securities, gross unrealized gains	407	455
AOCI, transfers from AFS to HTM Securities, gross unrealized losses	(200)	75
U.S. Treasury
Available-for-sale:
Amortized cost	32,360	28,966
Gross unrealized, Gain	114	771
Gross unrealized, Loss	2,007	328
Available-for-sale, amount	30,467	29,409
Held-to-maturity:
Amortized cost	11,347	11,617
Gross unrealized, Gains	0	36
Gross unrealized, Losses	685	103
Securities held-to-maturity	10,662	11,550
Sovereign debt/sovereign guaranteed
Available-for-sale:
Amortized cost	11,429	13,367
Gross unrealized, Gain	6	79
Gross unrealized, Loss	343	67
Available-for-sale, amount	11,092	13,379
Held-to-maturity:
Amortized cost	1,472	922
Gross unrealized, Gains	2	18
Gross unrealized, Losses	28	2
Securities held-to-maturity	1,446	938
Agency residential mortgage-backed securities (“RMBS”)
Available-for-sale:
Amortized cost	8,501	14,333
Gross unrealized, Gain	130	270
Gross unrealized, Loss	328	73
Available-for-sale, amount	8,303	14,530
Held-to-maturity:
Amortized cost	36,947	36,167
Gross unrealized, Gains	12	428
Gross unrealized, Losses	3,019	388
Securities held-to-maturity	33,940	36,207
Agency commercial mortgage-backed securities (“MBS”)
Available-for-sale:
Amortized cost	8,479	8,102
Gross unrealized, Gain	110	345
Gross unrealized, Loss	410	42
Available-for-sale, amount	8,179	8,405
Held-to-maturity:
Amortized cost	4,319	4,068
Gross unrealized, Gains	2	41
Gross unrealized, Losses	298	52
Securities held-to-maturity	4,023	4,057
Supranational
Available-for-sale:
Amortized cost	7,806	7,599
Gross unrealized, Gain	6	24
Gross unrealized, Loss	264	50
Available-for-sale, amount	7,548	7,573
Held-to-maturity:
Amortized cost	325	54
Gross unrealized, Gains	0	0
Gross unrealized, Losses	10	0
Securities held-to-maturity	315	54
Foreign covered bonds
Available-for-sale:
Amortized cost	6,010	6,236
Gross unrealized, Gain	3	25
Gross unrealized, Loss	185	23
Available-for-sale, amount	5,828	6,238
Collateralized loan obligations (“CLOs”)
Available-for-sale:
Amortized cost	5,247	4,441
Gross unrealized, Gain	1	3
Gross unrealized, Loss	151	5
Available-for-sale, amount	5,097	4,439
Held-to-maturity:
Amortized cost	983	983
Gross unrealized, Gains	0	0
Gross unrealized, Losses	34	1
Securities held-to-maturity	949	982
Non-agency commercial MBS
Available-for-sale:
Amortized cost	3,270	3,083
Gross unrealized, Gain	0	65
Gross unrealized, Loss	267	23
Available-for-sale, amount	3,003	3,125
Foreign government agencies
Available-for-sale:
Amortized cost	2,620	2,694
Gross unrealized, Gain	0	9
Gross unrealized, Loss	84	17
Available-for-sale, amount	2,536	2,686
Held-to-maturity:
Amortized cost	64
Gross unrealized, Gains	0
Gross unrealized, Losses	1
Securities held-to-maturity	63
Non-agency RMBS
Available-for-sale:
Amortized cost	2,413	2,641
Gross unrealized, Gain	57	132
Gross unrealized, Loss	159	25
Available-for-sale, amount	2,311	2,748
Held-to-maturity:
Amortized cost	34	43
Gross unrealized, Gains	2	2
Gross unrealized, Losses	1	0
Securities held-to-maturity	35	45
State and political subdivisions
Available-for-sale:
Amortized cost	2,262	2,543
Gross unrealized, Gain	2	11
Gross unrealized, Loss	241	40
Available-for-sale, amount	2,023	2,514
Held-to-maturity:
Amortized cost	14	14
Gross unrealized, Gains	0	1
Gross unrealized, Losses	1	0
Securities held-to-maturity	13	15
U.S. government agencies
Available-for-sale:
Amortized cost	2,003	2,464
Gross unrealized, Gain	58	99
Gross unrealized, Loss	136	27
Available-for-sale, amount	1,925	2,536
Held-to-maturity:
Amortized cost	4,061	2,998
Gross unrealized, Gains	0	0
Gross unrealized, Losses	380	71
Securities held-to-maturity	3,681	2,927
Other asset-backed securities (“ABS”)
Available-for-sale:
Amortized cost	1,771	2,205
Gross unrealized, Gain	0	7
Gross unrealized, Loss	103	22
Available-for-sale, amount	1,668	2,190
Corporate bonds
Available-for-sale:
Amortized cost	1,455	2,099
Gross unrealized, Gain	0	19
Gross unrealized, Loss	158	52
Available-for-sale, amount	1,297	2,066
Other debt securities
Available-for-sale:
Amortized cost	1	1
Gross unrealized, Gain	0	0
Gross unrealized, Loss	0	0
Available-for-sale, amount	$ 1	$ 1