Business Combinations - Additional Information (Details) - USD ($)		3 Months Ended
	Mar. 20, 2023	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Business Acquisition [Line Items]
Common stock, par value (in dollars per share)		$ 4		$ 4
Allowance for credit losses		$ 67,936,000	$ 58,223,000	$ 68,675,000	$ 59,093,000
Blackhawk Bancorp, Inc
Business Acquisition [Line Items]
Percentage of issued and outstanding shares acquired	100.00%
Common stock, par value (in dollars per share)	$ 0.01
Share Price	$ 4
Consideration paid in cash	$ 1,928
Consideration paid in shares	3,290,222
Conversion of common stock	1.15
Goodwill acquired during period	$ 50,100,000
Pre-tax of acquisition costs		$ 2,200,000	$ 93,000
Allowance for credit losses for loans identified as PCD	3,791,000
Purchased credit deteriorated loans	105,983,000
Blackhawk Bancorp, Inc | ASU 2016-13
Business Acquisition [Line Items]
Allowance for credit losses	3,800,000
Allowance for credit losses on non-PCD loans	$ 618,330,000
Blackhawk Bancorp, Inc | Core Deposit Intangibles
Business Acquisition [Line Items]
Intangible asset estimated useful life	10 years
Blackhawk Bancorp, Inc | Fair Value Adjustments
Business Acquisition [Line Items]
Loans, net	$ 722,866,000
Change in acquired time deposits	$ 1,194,972,000