Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net income	$ 91,729	$ 67,405	$ 20,044
Adjustments to reconcile net income to net cash provided by operating activities:
Net premium / discount amortization on securities	3,317	5,217	2,932
Securities losses (gains), net	4,148	944	(232)
Provision for credit losses	16,501	6,550	4,326
Originations of loans held-for-sale	(52,091)	(76,607)	(239,175)
Proceeds from sales of loans held-for-sale	52,186	81,776	254,374
Net gains on sales of mortgage loans	(1,477)	(2,022)	(9,300)
Mortgage servicing rights mark to market loss (gain)	1,425	(3,177)	(1,261)
Net accretion of discount on loans and unfunded commitments	(3,067)	(6,339)	(1,177)
Net change in cash surrender value of BOLI	(2,120)	(718)	(1,390)
Net gains on sale of other real estate owned	(256)	(163)	(41)
Provision for other real estate owned valuation losses	269	104	79
Depreciation of fixed assets and amortization of leasehold improvements	4,485	4,085	3,152
Write-down of fixed assets			3,809
Net gains on disposal and transfer of fixed assets	(623)	(2,017)
Amortization of core deposit intangibles	2,461	2,626	644
Change in current income taxes receivable	(4,872)	12,048	(9,286)
Deferred tax expense	1,857	969	6,479
Change in accrued interest receivable and other assets	(5,881)	(940)	6,865
Accretion of purchase accounting adjustment on time deposits	(1,226)	(1,582)	(155)
Change in accrued interest payable and other liabilities	6,033	6,225	(11,075)
Stock based compensation	3,603	2,960	1,435
Net cash provided by operating activities	116,401	97,344	31,047
Cash flows from investing activities
Proceeds from maturities and calls, including pay down of securities available-for-sale	186,049	279,848	138,874
Proceeds from sales of securities available-for-sale	205,738	30,981	605,846
Purchases of securities available-for-sale	(13,414)	(301,649)	(886,103)
Net purchases of FHLBC/FRBC stock	(12,825)	(7,273)
Net change in loans	(197,574)	(443,904)	122,102
Purchases of BOLI policies	(590)	(590)	(591)
Proceeds from sales of other real estate owned, net of participations and improvements	2,005	941	5,828
Proceeds from disposition of premises and equipment	4,542	13,346
Net purchases of premises and equipment	(12,376)	(4,332)	(2,033)
Cash paid for acquisition, net of cash and cash equivalents acquired		(146)	148,995
Net cash provided by (used in) investing activities	161,555	(432,778)	132,918
Cash flows from financing activities
Net change in deposits	(538,751)	(353,927)	235,078
Net change in securities sold under repurchase agreements	(5,686)	(18,181)	(16,643)
Net change in other short-term borrowings	315,000	90,000
Issuance of subordinated debentures, net of issuance costs			59,148
Repayment of term note	(9,000)	(4,000)	(4,000)
Net change in notes payable and other borrowings, excluding term note		(6,056)	(315)
Repayment of senior notes	(45,000)
Dividends paid on common stock	(8,946)	(8,877)	(4,612)
Purchase of treasury stock	(605)	(455)	(10,417)
Net cash (used in) provided by financing activities	(292,988)	(301,496)	258,239
Net change in cash and cash equivalents	(15,032)	(636,930)	422,204
Cash and cash equivalents at beginning of period	115,177	752,107	329,903
Cash and cash equivalents at end of period	100,145	115,177	752,107
Supplemental cash flow information
Income taxes paid, net	35,670	11,232	10,592
Interest paid for deposits	14,210	3,418	2,752
Interest paid for borrowings	24,238	6,777	5,366
Non-cash transfer of loans to other real estate owned	5,580	87	$ 196
Non-cash transfer of fixed assets to other assets	$ 582	$ 4,568