Acquisition and Divestiture - Summary Of Merger Related Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Accounts Notes And Loans Receivable [Line Items]
Outside data processing software	$ 95,068	$ 72,782	$ 268,607	$ 213,025
Advertising and marketing	21,398	15,208	58,057	43,200
Peoples United Financial Inc [Member]
Accounts Notes And Loans Receivable [Line Items]
Salaries and employee benefits	13,094	60	98,480	64
Equipment and net occupancy	2,106	1	4,415	1
Outside data processing software	2,277	625	3,245	869
Advertising and marketing	2,177	505	4,004	529
Printing, postage and supplies	651	730	3,833	2,779
Other cost of operations	32,722	6,905	179,231	18,428
Other expenses	$ 53,027	$ 8,826	$ 293,208	$ 22,670