Acquisition and Divestitures - Summary of Identifiable Assets Acquired, Liabilities Assumed and Preferred Stock Exchanged as of Acquisition (Details) - USD ($) $ in Millions	Apr. 01, 2022	Dec. 31, 2023	Dec. 31, 2022
Liabilities and preferred stock:
Total liabilities and shareholders’ equity		$ 208,264	$ 200,730
Goodwill		$ 8,465	$ 8,490
Peoples United Financial Inc [Member]
Consideration:
Common stock issued (50,325,004 shares)	$ 8,286
Common stock awards converted	105
Cash	2
Total consideration	8,393
Identifiable assets
Cash and due from banks	396
Interest-bearing deposits at banks	9,193
Investment securities	11,575
Loans and leases	35,841
Core deposit and other intangible assets	261
Other assets	2,979
Total identifiable assets acquired	60,245
Liabilities and preferred stock:
Deposits	52,968
Borrowings	1,389
Other liabilities	1,142
Total liabilities assumed	55,499
Preferred stock	261
Total liabilities and shareholders’ equity	55,760
Net assets acquired	4,485
Goodwill	$ 3,908