Investment Securities - Amortized Costs and Estimated Fair Values (Details) - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Available-for-sale securities
Amortized cost	$ 204,671,000,000		$ 216,188,000,000
Unallocated portfolio layer fair value hedge basis adjustments	21,000,000
Gross unrealized gains	1,274,000,000		890,000,000
Unallocated portfolio layer fair value basis adjustments, Gross unrealized gains	(21,000,000)
Gross unrealized losses	8,697,000,000		11,221,000,000
Fair value	197,248,000,000		205,857,000,000
Held-to-maturity securities
Amortized cost	412,827,000,000		425,305,000,000
Gross unrealized gains	201,000,000		105,000,000
Gross unrealized losses	31,038,000,000		36,762,000,000
Fair value	381,990,000,000		388,648,000,000
Total investment securities, net of allowance for credit losses
Amortized cost	617,498,000,000		641,493,000,000
Gross unrealized gains	1,475,000,000		995,000,000
Gross unrealized losses	39,735,000,000		47,983,000,000
Fair value	579,238,000,000		594,505,000,000
HTM securities purchased	3,600,000,000	$ 13,200,000,000
Investment securities, allowance for credit losses	90,000,000	41,000,000	96,000,000
Accrued interest receivables on investment securities	2,400,000,000		2,500,000,000
Accrued interest receivables reversed through interest income on AFS securities	0	0
Accrued interest receivables reversed through interest income on HTM securities	0	$ 0
Total mortgage-backed securities
Available-for-sale securities
Amortized cost	78,251,000,000		84,059,000,000
Gross unrealized gains	597,000,000		485,000,000
Gross unrealized losses	5,125,000,000		6,463,000,000
Fair value	73,723,000,000		78,081,000,000
Held-to-maturity securities
Amortized cost	134,329,000,000		134,356,000,000
Gross unrealized gains	99,000,000		48,000,000
Gross unrealized losses	13,759,000,000		15,687,000,000
Fair value	120,669,000,000		118,717,000,000
U.S. GSEs and government agencies
Available-for-sale securities
Amortized cost	71,570,000,000		77,194,000,000
Gross unrealized gains	592,000,000		479,000,000
Gross unrealized losses	4,857,000,000		6,170,000,000
Fair value	67,305,000,000		71,503,000,000
Held-to-maturity securities
Amortized cost	112,980,000,000		113,492,000,000
Gross unrealized gains	84,000,000		35,000,000
Gross unrealized losses	11,893,000,000		13,709,000,000
Fair value	101,171,000,000		99,818,000,000
Residential: U.S.
Available-for-sale securities
Amortized cost	1,695,000,000		1,576,000,000
Gross unrealized gains	1,000,000		1,000,000
Gross unrealized losses	103,000,000		111,000,000
Fair value	1,593,000,000		1,466,000,000
Held-to-maturity securities
Amortized cost	10,602,000,000		10,503,000,000
Gross unrealized gains	5,000,000		3,000,000
Gross unrealized losses	1,132,000,000		1,244,000,000
Fair value	9,475,000,000		9,262,000,000
Residential: Non-U.S.
Available-for-sale securities
Amortized cost	2,885,000,000		3,176,000,000
Gross unrealized gains	4,000,000		5,000,000
Gross unrealized losses	11,000,000		27,000,000
Fair value	2,878,000,000		3,154,000,000
Commercial
Available-for-sale securities
Amortized cost	2,101,000,000		2,113,000,000
Gross unrealized gains	0		0
Gross unrealized losses	154,000,000		155,000,000
Fair value	1,947,000,000		1,958,000,000
Held-to-maturity securities
Amortized cost	10,747,000,000		10,361,000,000
Gross unrealized gains	10,000,000		10,000,000
Gross unrealized losses	734,000,000		734,000,000
Fair value	10,023,000,000		9,637,000,000
U.S. Treasury and government agencies
Available-for-sale securities
Amortized cost	83,648,000,000		95,217,000,000
Gross unrealized gains	513,000,000		302,000,000
Gross unrealized losses	2,522,000,000		3,459,000,000
Fair value	81,639,000,000		92,060,000,000
Held-to-maturity securities
Amortized cost	202,487,000,000		207,463,000,000
Gross unrealized gains	0		0
Gross unrealized losses	15,275,000,000		18,363,000,000
Fair value	187,212,000,000		189,100,000,000
Obligations of U.S. states and municipalities
Available-for-sale securities
Amortized cost	13,692,000,000		7,103,000,000
Gross unrealized gains	166,000,000		86,000,000
Gross unrealized losses	329,000,000		403,000,000
Fair value	13,529,000,000		6,786,000,000
Held-to-maturity securities
Amortized cost	12,299,000,000		19,747,000,000
Gross unrealized gains	52,000,000		53,000,000
Gross unrealized losses	740,000,000		1,080,000,000
Fair value	11,611,000,000		18,720,000,000
Non-U.S. government debt securities
Available-for-sale securities
Amortized cost	19,960,000,000		20,360,000,000
Gross unrealized gains	13,000,000		14,000,000
Gross unrealized losses	543,000,000		678,000,000
Fair value	19,430,000,000		19,696,000,000
Corporate debt securities
Available-for-sale securities
Amortized cost	392,000,000		381,000,000
Gross unrealized gains	0		0
Gross unrealized losses	28,000,000		24,000,000
Fair value	364,000,000		357,000,000
Asset-backed securities: Collateralized loan obligations
Available-for-sale securities
Amortized cost	5,607,000,000		5,916,000,000
Gross unrealized gains	2,000,000		1,000,000
Gross unrealized losses	89,000,000		125,000,000
Fair value	5,520,000,000		5,792,000,000
Held-to-maturity securities
Amortized cost	61,528,000,000		61,414,000,000
Gross unrealized gains	50,000,000		4,000,000
Gross unrealized losses	1,175,000,000		1,522,000,000
Fair value	60,403,000,000		59,896,000,000
Asset-backed securities: Other
Available-for-sale securities
Amortized cost	3,100,000,000		3,152,000,000
Gross unrealized gains	4,000,000		2,000,000
Gross unrealized losses	61,000,000		69,000,000
Fair value	3,043,000,000		3,085,000,000
Held-to-maturity securities
Amortized cost	2,184,000,000		2,325,000,000
Gross unrealized gains	0		0
Gross unrealized losses	89,000,000		110,000,000
Fair value	$ 2,095,000,000		$ 2,215,000,000