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Goodwill and Other Intangible Assets - Additional Information (Details) - USD ($)			3 Months Ended		6 Months Ended
	Feb. 15, 2022	Aug. 31, 2021	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Goodwill [Line Items]
Goodwill impairment		$ 0
Impairment charges					$ 0	$ 0
Amortization of other intangible assets			$ 7,170,000	$ 2,909,000	$ 11,981,000	$ 5,984,000
Core Deposits and Other Intangible Assets \| Minimum
Goodwill [Line Items]
Estimated useful lives					5 years
Core Deposits and Other Intangible Assets \| Maximum
Goodwill [Line Items]
Estimated useful lives					15 years
Core deposit
Goodwill [Line Items]
Estimated fair value of intangible assets acquired					$ 77,900,000
Customer trust relationships
Goodwill [Line Items]
Estimated fair value of intangible assets acquired					39,700,000
First Midwest
Goodwill [Line Items]
Acquisitions and adjustments					$ 954,500,000
First Midwest \| Core deposit
Goodwill [Line Items]
Estimated useful lives	10 years
First Midwest \| Customer trust relationships
Goodwill [Line Items]
Estimated useful lives	13 years