Investment Securities - Amortized Costs and Estimated Fair Values (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Available-for-sale securities
Amortized cost	$ 231,904,000,000		$ 231,904,000,000		$ 308,254,000,000
Gross unrealized gains	743,000,000		743,000,000		2,614,000,000
Gross unrealized losses	10,578,000,000		10,578,000,000		2,343,000,000
Fair value	222,069,000,000		222,069,000,000		308,525,000,000
Held-to-maturity securities
Amortized cost	441,649,000,000		441,649,000,000		363,707,000,000
Gross unrealized gains	88,000,000		88,000,000		2,110,000,000
Gross unrealized losses	26,150,000,000		26,150,000,000		3,189,000,000
Fair value	415,587,000,000		415,587,000,000		362,628,000,000
Total investment securities, net of allowance for credit losses
Amortized cost	673,553,000,000		673,553,000,000		671,961,000,000
Gross unrealized gains	831,000,000		831,000,000		4,724,000,000
Gross unrealized losses	36,728,000,000		36,728,000,000		5,532,000,000
Fair value	637,656,000,000		637,656,000,000		671,153,000,000
HTM securities purchased	14,300,000,000	$ 31,800,000,000	27,500,000,000	$ 63,100,000,000
Investment securities, allowance for credit losses	47,000,000	87,000,000	47,000,000	87,000,000	42,000,000
Accrued interest receivables on investment securities	2,000,000,000		2,000,000,000		1,900,000,000
Accrued interest receivables reversed through interest income on AFS securities	0	0	0	0
Accrued interest receivables reversed through interest income on HTM securities	0	$ 0	0	$ 0
Total mortgage-backed securities
Available-for-sale securities
Amortized cost	76,322,000,000		76,322,000,000		83,754,000,000
Gross unrealized gains	262,000,000		262,000,000		821,000,000
Gross unrealized losses	5,267,000,000		5,267,000,000		1,013,000,000
Fair value	71,317,000,000		71,317,000,000		83,562,000,000
Held-to-maturity securities
Amortized cost	138,370,000,000		138,370,000,000		113,602,000,000
Gross unrealized gains	10,000,000		10,000,000		1,412,000,000
Gross unrealized losses	10,113,000,000		10,113,000,000		1,013,000,000
Fair value	128,267,000,000		128,267,000,000		114,001,000,000
U.S. GSEs and government agencies
Available-for-sale securities
Amortized cost	68,511,000,000		68,511,000,000		72,800,000,000
Gross unrealized gains	252,000,000		252,000,000		736,000,000
Gross unrealized losses	5,074,000,000		5,074,000,000		993,000,000
Fair value	63,689,000,000		63,689,000,000		72,543,000,000
Held-to-maturity securities
Amortized cost	117,088,000,000		117,088,000,000		102,556,000,000
Gross unrealized gains	7,000,000		7,000,000		1,400,000,000
Gross unrealized losses	8,734,000,000		8,734,000,000		853,000,000
Fair value	108,361,000,000		108,361,000,000		103,103,000,000
Residential: U.S.
Available-for-sale securities
Amortized cost	1,764,000,000		1,764,000,000		2,128,000,000
Gross unrealized gains	1,000,000		1,000,000		38,000,000
Gross unrealized losses	55,000,000		55,000,000		2,000,000
Fair value	1,710,000,000		1,710,000,000		2,164,000,000
Held-to-maturity securities
Amortized cost	11,206,000,000		11,206,000,000		7,316,000,000
Gross unrealized gains	1,000,000		1,000,000		1,000,000
Gross unrealized losses	834,000,000		834,000,000		106,000,000
Fair value	10,373,000,000		10,373,000,000		7,211,000,000
Residential: Non-U.S.
Available-for-sale securities
Amortized cost	3,776,000,000		3,776,000,000		3,882,000,000
Gross unrealized gains	9,000,000		9,000,000		25,000,000
Gross unrealized losses	20,000,000		20,000,000		1,000,000
Fair value	3,765,000,000		3,765,000,000		3,906,000,000
Commercial
Available-for-sale securities
Amortized cost	2,271,000,000		2,271,000,000		4,944,000,000
Gross unrealized gains	0		0		22,000,000
Gross unrealized losses	118,000,000		118,000,000		17,000,000
Fair value	2,153,000,000		2,153,000,000		4,949,000,000
Held-to-maturity securities
Amortized cost	10,076,000,000		10,076,000,000		3,730,000,000
Gross unrealized gains	2,000,000		2,000,000		11,000,000
Gross unrealized losses	545,000,000		545,000,000		54,000,000
Fair value	9,533,000,000		9,533,000,000		3,687,000,000
U.S. Treasury and government agencies
Available-for-sale securities
Amortized cost	113,811,000,000		113,811,000,000		178,038,000,000
Gross unrealized gains	323,000,000		323,000,000		668,000,000
Gross unrealized losses	4,150,000,000		4,150,000,000		1,243,000,000
Fair value	109,984,000,000		109,984,000,000		177,463,000,000
Held-to-maturity securities
Amortized cost	226,362,000,000		226,362,000,000		185,204,000,000
Gross unrealized gains	0		0		169,000,000
Gross unrealized losses	13,506,000,000		13,506,000,000		2,103,000,000
Fair value	212,856,000,000		212,856,000,000		183,270,000,000
Obligations of U.S. states and municipalities
Available-for-sale securities
Amortized cost	10,381,000,000		10,381,000,000		14,890,000,000
Gross unrealized gains	98,000,000		98,000,000		972,000,000
Gross unrealized losses	346,000,000		346,000,000		2,000,000
Fair value	10,133,000,000		10,133,000,000		15,860,000,000
Held-to-maturity securities
Amortized cost	19,167,000,000		19,167,000,000		13,985,000,000
Gross unrealized gains	78,000,000		78,000,000		453,000,000
Gross unrealized losses	939,000,000		939,000,000		44,000,000
Fair value	18,306,000,000		18,306,000,000		14,394,000,000
Non-U.S. government debt securities
Available-for-sale securities
Amortized cost	16,223,000,000		16,223,000,000		16,163,000,000
Gross unrealized gains	36,000,000		36,000,000		92,000,000
Gross unrealized losses	451,000,000		451,000,000		46,000,000
Fair value	15,808,000,000		15,808,000,000		16,209,000,000
Corporate debt securities
Available-for-sale securities
Amortized cost	353,000,000		353,000,000		332,000,000
Gross unrealized gains	0		0		8,000,000
Gross unrealized losses	34,000,000		34,000,000		19,000,000
Fair value	319,000,000		319,000,000		321,000,000
Asset-backed securities: Collateralized loan obligations
Available-for-sale securities
Amortized cost	11,268,000,000		11,268,000,000		9,674,000,000
Gross unrealized gains	1,000,000		1,000,000		6,000,000
Gross unrealized losses	297,000,000		297,000,000		18,000,000
Fair value	10,972,000,000		10,972,000,000		9,662,000,000
Held-to-maturity securities
Amortized cost	55,121,000,000		55,121,000,000		48,869,000,000
Gross unrealized gains	0		0		75,000,000
Gross unrealized losses	1,521,000,000		1,521,000,000		22,000,000
Fair value	53,600,000,000		53,600,000,000		48,922,000,000
Asset-backed securities: Other
Available-for-sale securities
Amortized cost	3,546,000,000		3,546,000,000		5,403,000,000
Gross unrealized gains	23,000,000		23,000,000		47,000,000
Gross unrealized losses	33,000,000		33,000,000		2,000,000
Fair value	3,536,000,000		3,536,000,000		5,448,000,000
Held-to-maturity securities
Amortized cost	2,629,000,000		2,629,000,000		2,047,000,000
Gross unrealized gains	0		0		1,000,000
Gross unrealized losses	71,000,000		71,000,000		7,000,000
Fair value	$ 2,558,000,000		$ 2,558,000,000		$ 2,041,000,000