Business Combinations - Summary of Fair Value of Assets Acquired and Liabilities Assumed (Details) - USD ($)	Mar. 20, 2023	Feb. 14, 2022	Sep. 30, 2023	Dec. 31, 2022
Assets
Goodwill			$ 196,461,000	$ 140,412,000
Delta Bancshare Company
Assets
Cash and due from banks		$ 82,473,000
Loans		418,509,000
Investment securities		182,123,000
Premises and equipment		9,030,000
Other assets		7,774,000
Allowance for credit losses		(863,000)
Goodwill		28,558,000
Total assets acquired		750,063,000
Liabilities
Deposits		560,378,000
Securities sold under agreements to repurchase		35,523,000
FHLB advances		45,075,000
Lease liability		717,000
Other liabilities		1,048,000
Total liabilities assumed		642,741,000
Net assets acquired		107,322,000
Consideration paid
Consideration payable in cash		15,150,000
Common stock		92,172,000
Total consideration paid		107,322,000
Delta Bancshare Company | Core Deposit Intangibles
Assets
Intangible assets		5,920,000
Delta Bancshare Company | Bank Owned Life Insurance
Assets
Intangible assets		15,822,000
Delta Bancshare Company | Right of Use Asset
Assets
Intangible assets		717,000
Delta Bancshare Company | Acquired Book Value
Assets
Cash and due from banks		82,473,000
Loans		426,433,000
Investment securities		184,959,000
Premises and equipment		5,522,000
Other assets		9,061,000
Allowance for credit losses		(5,388,000)
Goodwill		14,000
Total assets acquired		718,896,000
Liabilities
Deposits		558,619,000
Securities sold under agreements to repurchase		35,523,000
FHLB advances		45,000,000
Lease liability		0
Other liabilities		2,209,000
Total liabilities assumed		641,351,000
Net assets acquired		77,545,000
Delta Bancshare Company | Acquired Book Value | Core Deposit Intangibles
Assets
Intangible assets		0
Delta Bancshare Company | Acquired Book Value | Bank Owned Life Insurance
Assets
Intangible assets		15,822,000
Delta Bancshare Company | Acquired Book Value | Right of Use Asset
Assets
Intangible assets		0
Delta Bancshare Company | Fair Value Adjustments
Assets
Cash and due from banks		0
Loans		(7,924,000)
Investment securities		(2,836,000)
Premises and equipment		3,508,000
Other assets		(1,287,000)
Allowance for credit losses		4,525,000
Goodwill		28,544,000
Total assets acquired		31,167,000
Liabilities
Deposits		1,759,000
Securities sold under agreements to repurchase		0
FHLB advances		75,000
Lease liability		717,000
Other liabilities		(1,161,000)
Total liabilities assumed		1,390,000
Net assets acquired		29,777,000
Delta Bancshare Company | Fair Value Adjustments | Core Deposit Intangibles
Assets
Intangible assets		5,920,000
Delta Bancshare Company | Fair Value Adjustments | Right of Use Asset
Assets
Intangible assets		$ 717,000
Blackhawk Bancorp, Inc
Assets
Goodwill			$ 50,097,000
Consideration paid
Consideration payable in cash	$ 1,928
Total consideration paid	93,510,000
Blackhawk Bancorp, Inc | Fair Value Adjustments
Assets
Cash and due from banks	55,600,000
Loans held for sale	3,222,000
Loans	722,866,000
Investment securities	377,969,000
Short-term investments	869,000
FHLB stock	1,737,000
Premises and equipment	12,366,000
Accrued interest receivable	4,029,000
Prepaid expenses	1,182,000
Other assets	20,742,000
Core deposit intangible	34,590,000
Income tax receivable	2,077,000
Deferred tax asset	22,152,000
Mortgage servicing rights	7,031,000
Total assets acquired	1,266,432,000
Liabilities
Deposits	1,194,972,000
Subordinated and jr. subordinated debt	16,448,000
Accrued interest payable	1,091,000
Accrued and other liabilities	10,508,000
Total liabilities assumed	1,223,019,000
Net assets acquired	43,413,000
Consideration paid
Total consideration paid	93,510,000
Goodwill	$ 50,097,000