Share-Based Compensation (Details) - USD ($) shares in Thousands	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining shares available for issuance (in shares)	88
Cliff Vest
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation awards, vesting period	3 years
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted during period (in shares)	900
Share-based compensation awards, vesting period	3 years
Nonvested shares outstanding (in shares)	2,100
Unrecognized compensation expense	$ 28,500,000
Share-based compensation expense	$ 2,400,000	$ 700,000
Restricted Stock \| Second Anniversary of Grant Date
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	50.00%
Restricted Stock \| Third Anniversary of Grant Date
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	50.00%
Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted during period (in shares)	1,200
Nonvested shares outstanding (in shares)	2,100
Unrecognized compensation expense	$ 26,000,000
Share-based compensation expense	$ 2,400,000	$ 600,000
Restricted Stock Units \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation awards, vesting period	24 months
Restricted Stock Units \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation awards, vesting period	36 months
Stock Options \| Old National Bancorp
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incremental expense associated with conversion of stock appreciation rights	$ 0
Stock Appreciation Rights (SARs) \| Old National Bancorp
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Nonvested shares outstanding (in shares)	8

Amount, after tax, of expense for award under share-based payment arrangement.

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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-Publisher FASB
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- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of shares authorized for issuance under share-based payment arrangement.

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- Definition

An excess of the fair value of the modified award over the fair value of the award immediately before the modification.

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Percentage of vesting of award under share-based payment arrangement.

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