Acquisition and Divestiture - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended	9 Months Ended
	Apr. 01, 2022	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2022	Sep. 30, 2021	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Carrying Value		$ 2,010,600		$ 2,010,600	$ 2,010,600			$ 1,750,000
Goodwill		8,501,357		8,501,357	8,501,357			4,593,112
ACL for non-PCD loan and leases	$ 242,000
Initial estimate of expected credit losses	99,000
Purchase Credit-Deteriorated	3,400,000
Assets		197,955,479		197,955,479	197,955,479			155,107,160
Shareholders' equity		25,256,493	$ 17,528,771	25,256,493	25,256,493	$ 17,528,771	$ 25,794,531	17,903,405	$ 16,720,304	$ 16,187,283
Net income (loss)		646,596	495,460		1,226,292	1,400,778
Common Stock [Member]
Business Acquisition [Line Items]
Shareholders' equity		89,718	$ 79,871	89,718	89,718	79,871	$ 89,718	79,871	$ 79,871	$ 79,871
Peoples United Financial Inc [Member]
Business Acquisition [Line Items]
Business combination, market value	$ 8,400,000
Common stock, price per share	$ 164.66
Assets	$ 60,244,818
Goodwill	3,908,245	8,501,357		8,501,357	8,501,357			$ 4,593,112
Core deposits and other intangible assets	261,000
ACL for non-PCD loan and leases	$ 242,000
Revenues				1,000,000	96,000
Net income (loss)				13,000	32,600
Peoples United Financial Inc [Member] | Core Deposit and Other Intangible Assets [Member] | Minimum [Member]
Business Acquisition [Line Items]
Amortization period	3 years
Peoples United Financial Inc [Member] | Core Deposit and Other Intangible Assets [Member] | Maximum [Member]
Business Acquisition [Line Items]
Amortization period	7 years
Peoples United Financial Inc [Member] | Common Stock [Member]
Business Acquisition [Line Items]
Common stock issued in transaction	50,325,004
MT [Member]
Business Acquisition [Line Items]
Common stock, price per share	$ 0.118
M&T Insurance Agency, Inc [Member]
Business Acquisition [Line Items]
Gain (loss) on sale of subsidiary, pre-tax					135,000
Assets		25,000		25,000	25,000
Shareholders' equity		$ 10		$ 10	10
Revenues					31,000	29,000
Net income (loss)					$ 4	$ 1