Business Segment Information - Amounts of Consolidated Revenue, Expense, Tax and Assets by Segment (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Net interest income (expense)	$ 662			$ 492			$ 1,683	$ 1,496
Provision for credit losses	60			(85)			50	(245)
Noninterest income	213			247			642	829
Noninterest expense	469			526			1,450	1,567
Income (loss) before income taxes	346			298			825	1,003
Income tax expense (benefit)	78			63			183	222
Net income (loss)	268	$ 177	$ 198	235	$ 311	$ 236	642	781
Average assets	82,550			88,401			85,799	87,131
Gain on disposition of business							21	0
TD Merger Agreement
Disaggregation of Revenue [Line Items]
Merger and integration expense	21						55
Regional Banking
Disaggregation of Revenue [Line Items]
Net interest income (expense)	517			444			1,410	1,319
Provision for credit losses	43			(52)			64	(169)
Noninterest income	110			113			337	323
Noninterest expense	304			292			911	837
Income (loss) before income taxes	280			317			772	974
Income tax expense (benefit)	65			74			181	228
Net income (loss)	215			243			591	746
Average assets	42,815			40,908			41,779	41,931
Specialty Banking
Disaggregation of Revenue [Line Items]
Net interest income (expense)	138			154			424	466
Provision for credit losses	17			(33)			(4)	(60)
Noninterest income	64			142			265	477
Noninterest expense	104			139			349	441
Income (loss) before income taxes	81			190			344	562
Income tax expense (benefit)	20			46			84	136
Net income (loss)	61			144			260	426
Average assets	19,749			20,505			20,071	20,717
Corporate
Disaggregation of Revenue [Line Items]
Net interest income (expense)	7			(106)			(151)	(289)
Provision for credit losses	0			0			(10)	(16)
Noninterest income	39			(8)			40	29
Noninterest expense	61			95			190	289
Income (loss) before income taxes	(15)			(209)			(291)	(533)
Income tax expense (benefit)	(7)			(57)			(82)	(142)
Net income (loss)	(8)			(152)			(209)	(391)
Average assets	19,986			26,988			23,949	24,483
Gain on disposition of business	21						21
Corporate | TD Merger Agreement
Disaggregation of Revenue [Line Items]
Merger and integration expense	$ 24			$ 46			$ 99	$ 148