Acquisition and Divestiture - Summary of Identifiable Assets Acquired, Liabilities Assumed and Preferred Stock Exchanged as of Acquisition (Details) - USD ($) $ in Thousands	Apr. 01, 2022	Sep. 30, 2023	Dec. 31, 2022
Liabilities and preferred stock:
Total liabilities and shareholders’ equity		$ 209,124,316	$ 200,729,841
Goodwill		$ 8,465,089	$ 8,490,089
Peoples United Financial Inc [Member]
Consideration:
Common stock issued (50,325,004 shares)	$ 8,286,515
Common stock awards converted	104,810
Cash	1,824
Total consideration	8,393,149
Identifiable assets
Cash and due from banks	395,747
Interest-bearing deposits at banks	9,193,346
Investment securities	11,574,689
Loans and leases	35,840,648
Core deposit and other intangible assets	261,000
Other assets	2,979,388
Total identifiable assets acquired	60,244,818
Liabilities and preferred stock:
Deposits	52,967,915
Borrowings	1,389,012
Other liabilities	1,142,387
Total liabilities assumed	55,499,314
Preferred stock	260,600
Total liabilities and shareholders’ equity	55,759,914
Net assets acquired	4,484,904
Goodwill	$ 3,908,245