Consolidated Statement of Cash Flows - USD ($) $ in Millions	3 Months Ended				6 Months Ended		12 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Operating Activities:
Net income	$ 694	$ 634	$ 587	$ 508	$ 1,328	$ 1,095
Adjustments to reconcile net income to net cash provided by operating activities:
Deferred income tax expense (benefit)					3	56
Amortization of other intangible assets	58		59		116	119	$ 236
Other non-cash adjustments for depreciation, amortization and accretion, net					568	515
Losses (gains) related to investment securities, net					(2)	(1)
Change in trading account assets, net					31	(34)
Change in accrued interest and fees receivable, net					(3)	1
Change in collateral deposits, net					166	(3,711)
Change in unrealized losses (gains) on foreign exchange derivatives, net					(789)	1,601
Change in other assets, net					(844)	(1,317)
Change in accrued expenses and other liabilities, net					4,494	1,107
Other, net					307	242
Net cash provided by (used in) operating activities					5,375	(327)
Investing Activities:
Net decrease (increase) in interest-bearing deposits with banks					(21,234)	10,506
Net decrease (increase) in securities purchased under resale agreements					(2,539)	2,947
Proceeds from sales of available-for-sale securities					2,086	3,947
Proceeds from maturities of available-for-sale securities					10,147	9,166
Purchases of available-for-sale securities					(16,761)	(20,216)
Purchases of held-to-maturity securities under the MMLF program					(29,242)	0
Proceeds from maturities of held-to-maturity securities under the MMLF program					18,014	0
Proceeds from maturities of held-to-maturity securities					6,041	4,917
Purchases of held-to-maturity securities					(3,997)	(2,797)
Net (increase) in loans					(551)
Net (increase) in loans						369
Business acquisitions, net of cash acquired					0	(54)
Purchases of equity investments and other long-term assets					(810)	(184)
Purchases of premises and equipment, net					(271)	(342)
Other, net					822	294
Net cash (used in) provided by investing activities					(38,295)	8,553
Financing Activities:
Net (decrease) increase in time deposits					(33,097)	(5,228)
Net increase (decrease) in all other deposits					51,686	(4,538)
Net increase in short-term borrowings under money market liquidity facility					11,261	0
Net (decrease) increase in other short-term borrowings					2,484	2,594
Proceeds from issuance of long-term debt, net of issuance costs					2,497	0
Payments for long-term debt and obligations under finance leases					(16)	(39)
Payments for redemption of preferred stock					(500)	0
Repurchases of common stock					(515)	(600)
Repurchases of common stock for employee tax withholding					(52)	(56)
Payments for cash dividends					(445)	(461)
Net cash (used in) financing activities					33,303	(8,328)
Net increase					383	(102)
Cash and due from banks at beginning of period		$ 3,302		$ 3,212	3,302	3,212	3,212
Cash and due from banks at end of period	$ 3,685		$ 3,110		$ 3,685	$ 3,110	$ 3,302