Loans and Allowance for Credit Losses - Schedule of Activity in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at Beginning of Period	$ 288,003	$ 109,444	$ 107,341	$ 131,388
Allowance established for acquired PCD loans	10,558	0	89,089	0
Charge-offs	(11,440)	(1,215)	(20,200)	(3,765)
Recoveries	3,845	4,252	8,073	7,143
Provision for Credit Losses	11,288	(4,613)	117,951	(26,898)
Balance at End of Period	302,254	107,868	302,254	107,868
First Midwest
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance established for acquired PCD loans	10,600		89,100
Balance at End of Period	96,300		96,300
Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at Beginning of Period	102,819	25,731	27,232	30,567
Allowance established for acquired PCD loans	3,740	0	38,780	0
Charge-offs	(2,696)	(354)	(5,919)	(940)
Recoveries	2,206	106	3,219	549
Provision for Credit Losses	6,344	677	49,101	(4,016)
Balance at End of Period	112,413	26,160	112,413	26,160
Commercial real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at Beginning of Period	141,802	65,469	64,004	75,810
Allowance established for acquired PCD loans	6,818	0	49,419	0
Charge-offs	(4,772)	(86)	(5,596)	(264)
Recoveries	287	3,371	789	3,555
Provision for Credit Losses	(45)	(3,657)	35,474	(14,004)
Balance at End of Period	144,090	65,097	144,090	65,097
BBCC
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at Beginning of Period	2,064	2,798	2,458	6,120
Allowance established for acquired PCD loans	0	0	0	0
Charge-offs	0	(8)	(48)	(144)
Recoveries	108	31	256	87
Provision for Credit Losses	(4)	(259)	(498)	(3,501)
Balance at End of Period	2,168	2,562	2,168	2,562
Residential real estate
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at Beginning of Period	19,729	10,419	9,347	12,608
Allowance established for acquired PCD loans	0	0	136	0
Charge-offs	(20)	(85)	(344)	(305)
Recoveries	66	79	636	217
Provision for Credit Losses	1,481	(887)	11,481	(2,994)
Balance at End of Period	21,256	9,526	21,256	9,526
Indirect
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at Beginning of Period	1,641	2,043	1,743	3,580
Allowance established for acquired PCD loans	0	0	0	0
Charge-offs	(624)	(113)	(1,636)	(903)
Recoveries	379	294	921	1,395
Provision for Credit Losses	189	(363)	557	(2,211)
Balance at End of Period	1,585	1,861	1,585	1,861
Direct
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at Beginning of Period	14,412	640	528	855
Allowance established for acquired PCD loans	0	0	31	0
Charge-offs	(3,299)	(355)	(6,550)	(913)
Recoveries	442	153	1,712	622
Provision for Credit Losses	4,541	148	20,375	22
Balance at End of Period	16,096	586	16,096	586
Home equity
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance at Beginning of Period	5,536	2,344	2,029	1,848
Allowance established for acquired PCD loans	0	0	723	0
Charge-offs	(29)	(214)	(107)	(296)
Recoveries	357	218	540	718
Provision for Credit Losses	(1,218)	(272)	1,461	(194)
Balance at End of Period	$ 4,646	$ 2,076	$ 4,646	$ 2,076