Consolidated Statement of Cash Flows - USD ($) $ in Millions	3 Months Ended				6 Months Ended		12 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Operating Activities:
Net income	$ 587	$ 508	$ 733	$ 659	$ 1,095	$ 1,392
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Deferred income tax expense (benefit)					56	(89)
Amortization of other intangible assets	59		48		119	98	$ 226
Other non-cash adjustments for depreciation, amortization and accretion, net					515	489
(Gains) losses related to investment securities, net					(1)	(7)
Change in trading account assets, net					(34)	(67)
Change in accrued interest and fees receivable, net					1	13
Change in collateral deposits, net					(3,711)	3,159
Change in unrealized (gains) losses on foreign exchange derivatives, net					1,601	(2,956)
Change in other assets, net					(1,070)	(276)
Change in accrued expenses and other liabilities, net					1,107	1,378
Other, net					242	268
Net cash (used in) provided by operating activities					(80)	3,402
Investing Activities:
Net (increase) decrease in interest-bearing deposits with banks					10,506	(9,139)
Net (increase) decrease in securities purchased under resale agreements					2,947	(342)
Proceeds from sales of available-for-sale securities					3,947	15,687
Proceeds from maturities of available-for-sale securities					9,166	8,009
Purchases of available-for-sale securities					(20,216)	(15,459)
Proceeds from maturities of held-to-maturity securities					4,917	2,863
Purchases of held-to-maturity securities					(2,797)	(2,102)
Net decrease (increase) in loans and leases					369
Net decrease (increase) in loans and leases						(819)
Business acquisitions, net of cash acquired					(54)	0
Purchases of equity investments and other long-term assets					(184)	(173)
Purchases of premises and equipment, net					(342)	(285)
Other, net					294	28
Net cash provided by (used in) investing activities					8,553	(1,732)
Financing Activities:
Net (decrease) in time deposits					(5,228)	2,727
Net (decrease) increase in all other deposits					(4,538)	(960)
Net increase (decrease) in other short-term borrowings					2,594	205
Payments for long-term debt and obligations under capital leases					(39)	(1,024)
Repurchases of common stock					(600)	(350)
Repurchases of common stock for employee tax withholding					(56)	(90)
Payments for cash dividends					(461)	(399)
Net cash (used in) provided by financing activities					(8,328)	109
Net increase					145	1,779
Cash and due from banks at beginning of period		$ 3,597		$ 2,107	3,597	2,107	2,107
Cash and due from banks at end of period	$ 3,742		$ 3,886		$ 3,742	$ 3,886	$ 3,597