Acquisitions (Details Textuals) $ in Thousands				3 Months Ended		12 Months Ended
	Dec. 11, 2020 USD ($) branch	Jun. 30, 2020 USD ($)	Feb. 14, 2020 USD ($) branch	Mar. 31, 2021 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2021 USD ($)	Mar. 01, 2021 USD ($)	Feb. 26, 2021 USD ($) branch	Dec. 31, 2020 USD ($)
Business Acquisition [Line Items]
Deposits						$ 28,466,430			$ 26,482,481
First Staunton Bancshares
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition			Feb. 14, 2020
Business Combination, Control Obtained Description			The purchase price was based on an assumed 4% deposit premium at announcement.
Business Acquisition, Name of Acquired Entity			First Staunton
New Communities | branch			9
Acquired Net Branches | branch			7
Goodwill			$ 14,812			$ 15,000
PCD-HTM Securities			0
PCD-AFS Securities			0
Total consideration paid			$ 76,300
Huntington National Bank [Member]
Business Acquisition [Line Items]
Business Combination, Control Obtained Description	received a 4% purchase premium
Monroe, WI [Member]
Business Acquisition [Line Items]
Business Combination, Control Obtained Description	4
ABRC [Member]
Business Acquisition [Line Items]
Goodwill					$ 82,000
Total consideration paid		$ 266,000
Gain (Loss) on Disposition of Intangible Assets		$ 163,000
Peoria, IL [Member]
Business Acquisition [Line Items]
disposed net branches | branch	5
Deposits	$ 180,000
Southwest Wisconsin [Member]
Business Acquisition [Line Items]
disposed net branches | branch	2
Deposits	$ 53,000
Monroe, WI [Member]
Business Acquisition [Line Items]
disposed net branches | branch								1
Deposits								$ 31,000
Whitnell
Business Acquisition [Line Items]
Disposal Group, Including Discontinued Operation, Consideration							$ 8,000
Gain (Loss) on Sale and Maturity of Other Investments, Before Tax				$ 2,000
Goodwill				$ 4,000