Consolidated Statement of Cash Flows - USD ($) $ in Millions	3 Months Ended				6 Months Ended		12 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Operating Activities:
Net income	$ 763	$ 519	$ 694	$ 634	$ 1,282	$ 1,328
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income tax (benefit)					(15)	3
Amortization of other intangible assets	63		58		121	116	$ 234
Other non-cash adjustments for depreciation, amortization and accretion, net					700	568
Losses (gains) related to investment securities, net					0	(2)
Provision for credit losses					(24)	88
Change in trading account assets, net					94	31
Change in accrued interest and fees receivable, net					(254)	(3)
Change in collateral deposits, net					(6,520)	166
Change in unrealized losses (gains) on foreign exchange derivatives, net					(7,471)	(789)
Change in other assets, net					(1,444)	(844)
Change in accrued expenses and other liabilities, net					1,971	4,494
Other, net					235	219
Net cash (used in) provided by operating activities					(11,325)	5,375
Investing Activities:
Net (increase) decrease in interest-bearing deposits with banks					3,613	(21,234)
Net (increase) decrease in securities purchased under resale agreements					(891)	(2,539)
Proceeds from sales of available-for-sale securities					6,854	2,086
Proceeds from maturities of available-for-sale securities					11,090	10,147
Purchases of available-for-sale securities					(28,565)	(16,761)
Purchases of held-to-maturity securities under the MMLF program					0	(29,242)
Proceeds from maturities of held-to-maturity securities under the MMLF program					3,299	18,014
Proceeds from maturities of held-to-maturity securities					7,886	6,041
Purchases of held-to-maturity securities					(3,070)	(4,185)
Sale of loans					40	188
Net (increase) in loans					(2,819)	(551)
Business acquisitions, net of cash acquired					(257)	0
Divestitures					13	0
Purchases of equity investments and other long-term assets					(106)	(810)
Purchases of premises and equipment, net					(359)	(271)
Other, net					184	822
Net cash provided by (used in) investing activities					(3,088)	(38,295)
Financing Activities:
Net (decrease) increase in time deposits					(1,542)	(33,097)
Net increase (decrease) in all other deposits					25,724	51,686
Net (decrease) increase in securities sold under repurchase agreements					(2,756)	2,411
Net (decrease) increase in short-term borrowings under money market liquidity facility					(3,302)	11,261
Net (decrease) increase in other short-term borrowings					(51)	73
Proceeds from issuance of long-term debt, net of issuance costs					844	2,497
Payments for long-term debt and obligations under finance leases					(1,522)	(16)
Payments for redemption of preferred stock					(500)	(500)
Repurchases of common stock					(900)	(515)
Repurchases of common stock for employee tax withholding					(6)	(52)
Payments for cash dividends					(424)	(445)
Net cash (used in) provided by financing activities					15,565	33,303
Net increase					1,152	383
Cash and due from banks at beginning of period		$ 3,467		$ 3,302	3,467	3,302	3,302
Cash and due from banks at end of period	$ 4,619		$ 3,685		$ 4,619	$ 3,685	$ 3,467