Acquisitions - Schedule of Acquisition Activity (Details) - Northern States Financial Corporation $ / shares in Units, $ in Thousands	Oct. 12, 2018 USD ($) $ / shares shares
Assets
Cash and due from banks and interest-bearing deposits in other banks	$ 160,145
Equity securities	3,915
Securities available-for-sale	47,149
FHLB and FRB stock	554
Loans	284,924
OREO	2,549
Investment in BOLI	11,104
Goodwill	30,518
Other intangible assets	12,230
Premises, furniture, and equipment	5,414
Accrued interest receivable and other assets	20,170
Total assets	578,672
Liabilities
Noninterest-bearing deposits	346,714
Interest-bearing deposits	116,446
Total deposits	463,160
Borrowed funds	18,218
Senior and subordinated debt	8,038
Accrued interest payable and other liabilities	5,953
Total liabilities	495,369
Consideration Paid
Common stock (2018 - 3,310,912, shares issued at $25.16 per share), net of issuance costs	83,303
Cash paid	0
Total consideration paid	$ 83,303
Common stock, shares issued (in shares) | shares	3,310,912
Shares issued (in dollars per share) | $ / shares	$ 25.16