Accumulated Other Comprehensive Income - Reclassification Out of AOCI (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Securities gains, net	[1]	$ 21	$ 8	$ (3)	$ 25
Interest and fees on loans and leases		1,115	1,336	2,350	2,479
Compensation and benefits	[1]	627	641	1,274	1,251
Income (loss) before income taxes		244	577	304	1,572
Applicable income tax expense		49	124	61	344
Net income		195	453	243	1,228
Reclassification out of AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net income		48	(2)	72	(6)
Reclassification out of AOCI | Net unrealized gains on available-for-sale debt securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Securities gains, net		0	0	0	(1)
Income (loss) before income taxes		0	0	0	(1)
Applicable income tax expense		0	0	0	0
Net income		0	0	0	(1)
Reclassification out of AOCI | Net unrealized gains on cash flow hedge
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest and fees on loans and leases		62	(1)	94	(3)
Income (loss) before income taxes		62	(1)	94	(3)
Applicable income tax expense		(13)	0	(20)	0
Net income		49	(1)	74	(3)
Reclassification out of AOCI | Net periodic benefit costs
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Compensation and benefits		(1)	(1)	(3)	(2)
Income (loss) before income taxes		(1)	(1)	(3)	(2)
Applicable income tax expense		0	0	1	0
Net income		$ (1)	$ (1)	$ (2)	$ (2)

[1] During the first quarter of 2020, certain noninterest income and noninterest expense line items were reclassified to better align disclosures to business activities. These reclassifications were retrospectively applied to all prior periods presented. Total noninterest income and noninterest expense did not change as a result of these reclassifications.