Business Segment Information - Amounts of Consolidated Revenue, Expense, Tax and Assets by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Disaggregation of Revenue [Line Items]
Net interest income (expense)	$ 479	$ 508
Provision for credit losses	(40)	(45)
Noninterest income	229	298
Noninterest expense	493	544
Income (loss) before income taxes	255	307
Income tax expense (benefit)	57	71
Net income (loss)	198	236
Average assets	88,587	85,401
TD Merger Agreement
Disaggregation of Revenue [Line Items]
Merger and integration expense	9
Regional Banking
Disaggregation of Revenue [Line Items]
Net interest income (expense)	425	430
Provision for credit losses	(30)	(29)
Noninterest income	114	100
Noninterest expense	310	270
Income (loss) before income taxes	259	289
Income tax expense (benefit)	61	67
Net income (loss)	198	222
Average assets	40,453	42,379
Specialty Banking
Disaggregation of Revenue [Line Items]
Net interest income (expense)	141	158
Provision for credit losses	(3)	(6)
Noninterest income	105	185
Noninterest expense	136	154
Income (loss) before income taxes	113	195
Income tax expense (benefit)	27	47
Net income (loss)	86	148
Average assets	20,228	21,556
Corporate
Disaggregation of Revenue [Line Items]
Net interest income (expense)	(87)	(80)
Provision for credit losses	(7)	(10)
Noninterest income	10	13
Noninterest expense	47	120
Income (loss) before income taxes	(117)	(177)
Income tax expense (benefit)	(31)	(43)
Net income (loss)	(86)	(134)
Average assets	27,906	21,466
Corporate | TD Merger Agreement
Disaggregation of Revenue [Line Items]
Merger and integration expense	$ 37	$ 70