Operating Segments (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)		$ 6,682	$ 6,535	$ 6,321
Allocated provision for credit losses		566	547	572
Segment net interest income after provision		6,116	5,988	5,749
Noninterest income		4,876	4,782	4,472
Noninterest expense		6,932	7,444	6,721
Income before income taxes		4,060	3,326	3,500
Provision for income taxes		803	911	1,058
Net income		3,257	2,415	2,442
Identifiable assets (period end)		225,697	221,642
CB-Retail
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)		3,451	3,415	3,290
CB-Commercial
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)		2,000	1,741	1,604
FS&CF
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)		689	583	511
IH
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)		119	98	86
OT&C
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)	[1]	423	698	830
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)		6,682	6,535	6,321
Allocated provision for credit losses		566	547	572
Segment net interest income after provision		6,116	5,988	5,749
Noninterest income		4,876	4,782	4,472
Noninterest expense		6,932	7,444	6,721
Income before income taxes		4,060	3,326	3,500
Provision for income taxes		803	911	1,058
Net income		3,257	2,415	2,442
Identifiable assets (period end)		225,697	221,642	219,276
Operating Segments | CB-Retail
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)		3,731	3,561	3,403
Allocated provision for credit losses		504	502	475
Segment net interest income after provision		3,227	3,059	2,928
Noninterest income		1,394	1,408	1,358
Noninterest expense		2,654	2,724	2,480
Income before income taxes		1,967	1,743	1,806
Provision for income taxes		483	650	684
Net income		1,484	1,093	1,122
Identifiable assets (period end)		73,793	71,263	74,747
Operating Segments | CB-Commercial
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)		2,241	2,120	2,008
Allocated provision for credit losses		112	68	(41)
Segment net interest income after provision		2,129	2,052	2,049
Noninterest income		437	427	397
Noninterest expense		1,036	1,206	1,330
Income before income taxes		1,530	1,273	1,116
Provision for income taxes		342	441	394
Net income		1,188	832	722
Identifiable assets (period end)		57,044	56,566	55,038
Operating Segments | FS&CF
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)		773	710	653
Allocated provision for credit losses		1	(15)	128
Segment net interest income after provision		772	725	525
Noninterest income		1,235	1,181	1,148
Noninterest expense		1,259	1,190	1,141
Income before income taxes		748	716	532
Provision for income taxes		155	225	156
Net income		593	491	376
Identifiable assets (period end)		31,740	29,144	26,795
Operating Segments | IH
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)		87	77	67
Allocated provision for credit losses		2	4	3
Segment net interest income after provision		85	73	64
Noninterest income		1,871	1,777	1,731
Noninterest expense		1,614	1,590	1,524
Income before income taxes		342	260	271
Provision for income taxes		87	99	105
Net income		255	161	166
Identifiable assets (period end)		6,622	6,024	5,943
Operating Segments | OT&C
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)	[1]	(150)	67	190
Allocated provision for credit losses	[1]	(53)	(12)	7
Segment net interest income after provision	[1]	(97)	79	183
Noninterest income	[1]	(61)	(11)	(162)
Noninterest expense	[1]	369	734	246
Income before income taxes	[1]	(527)	(666)	(225)
Provision for income taxes	[1]	(264)	(504)	(281)
Net income	[1]	(263)	(162)	56
Identifiable assets (period end)	[1]	56,498	58,645	56,753
Intersegment Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)		0	0	0
Intersegment Eliminations | CB-Retail
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)		280	146	113
Intersegment Eliminations | CB-Commercial
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)		241	379	404
Intersegment Eliminations | FS&CF
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)		84	127	142
Intersegment Eliminations | IH
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)		(32)	(21)	(19)
Intersegment Eliminations | OT&C
Segment Reporting, Revenue Reconciling Item [Line Items]
Net interest income (expense)	[1]	$ (573)	$ (631)	$ (640)

[1] Includes financial data from business units below the quantitative and qualitative thresholds requiring disclosure.