Business Combinations - Narrative (Details) $ / shares in Units, $ in Millions			3 Months Ended
	Mar. 27, 2023 USD ($) $ / shares	Jan. 03, 2022 USD ($) $ / shares shares	Mar. 31, 2023 USD ($) $ / shares	Mar. 31, 2022 USD ($)	Dec. 31, 2022 $ / shares
Business Acquisition [Line Items]
Net interest income			$ 850	$ 649
Noninterest income			10,259	850
Net income			9,518	271
Gain on acquisition			9,824	431
Operating Segments | Silicon Valley Banking
Business Acquisition [Line Items]
Net interest income			65	0
Noninterest income			14	0
Net income			$ 35	$ 0
SVB
Business Acquisition [Line Items]
Total assets acquired	$ 106,600
Loans and leases	68,503
Cash and interest-earning deposits at banks	35,280
Total liabilities assumed	61,126
Deposits	55,959
Assets acquired, discount	16,450
Business combination, consideration transferred, liabilities incurred	35,150
Cash settled value appreciation instrument issued and issuable, base amount	$ 5
Number of trading days	2 days
Cash settled value appreciation instrument, threshold amount | $ / shares	$ 582.55
Cash settled value appreciation instrument, maximum amount	$ 500
Payment to acquire business, value appreciation instrument exercised	500
Business combination, financing receivable acquired, amount covered by share-loss agreement	$ 60,000
Business combination, financing receivable acquired, amount covered by share-loss agreement, coverage percentage for loss up to $5 billion	0.00%
Business combination, financing receivable acquired, amount covered by share-loss agreement, coverage percentage for loss in excess of $5 billion	$ 5,000
Business combination, financing receivable acquired, above threshold amount covered by share-loss agreement, percentage	50.00%
Share-Loss Agreement, reimbursement percentage	50.00%
Share-Loss Agreement, term	5 years
Share-Loss Agreement, reimbursement term	8 years
Share-Loss Agreement, true-up payment term	45 days
True-up amount	$ 1,500
Preliminary gain on acquisition, after income taxes	9,824
Initial PCD ACL	(200)
Business combination asset acquired, discount	16,450
Gain on acquisition	$ 13,134
SVB | FDIC Credit Facility
Business Acquisition [Line Items]
Debt instrument, term	5 years
FDIC advances, maximum amount available	$ 70,000
FHLB, advances, interest rate	0.00%
SVB | Secured Debt | FDIC Credit Facility | Secured Overnight Financing Rate (SOFR)
Business Acquisition [Line Items]
Basis spread on variable rate	0.25%
SVB | Purchase Money Note | Secured Debt
Business Acquisition [Line Items]
Debt instrument, term	5 years
Business combination, consideration transferred, liabilities incurred	$ 35,000
Debt instrument, stated interest rate	3.50%
CIT Group Inc.
Business Acquisition [Line Items]
Total assets acquired		$ 53,775
Loans and leases		32,714
Cash and interest-earning deposits at banks		3,060
Total liabilities assumed		47,392
Deposits		39,428
Gain on acquisition		$ 431
Class A Common Stock
Business Acquisition [Line Items]
Common stock, par value (in dollars per share) | $ / shares			$ 1		$ 1
Class A Common Stock | CIT Group Inc.
Business Acquisition [Line Items]
Common stock, terms of conversion, conversion ratio		0.062
Business acquisition, equity interest Issued or issuable (in shares) | shares		6,140,010
CIT Group Inc.
Business Acquisition [Line Items]
Common stock, par value (in dollars per share) | $ / shares		$ 0.01