Defined contribution plans employee contribution percentage of eligible compensation matched by employer.

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The number of company shares in the 401(k) plan. Company shares owned through the 401(k) plan are included in the calculation of weighted-average shares outstanding for purposes of calculating basic and diluted earnings-per-share.

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Amount of cost for defined contribution plan.

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Amount of discretionary contributions made by an employer to a defined contribution plan.

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Percentage employer matches of the employee's percentage contribution matched.

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

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of tax benefit for recognition of expense of award under share-based payment arrangement.

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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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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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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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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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Number of shares of stock issued as of the balance sheet date, including shares that had been issued and were previously outstanding but which are now held in the treasury.

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Share-Based Compensation and Other Employee Benefit Plans - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining shares available for issuance (in shares)	7,600,000
Increase in number of shares authorized for issuance (in shares)	$ 27,900,000	$ 28,700,000	$ 7,500,000
Total income tax benefit, stock-based compensation cost	6,900,000	7,100,000	1,800,000
Discretionary profit sharing	$ 0	$ 0	0
Shares allocated to the employee stock ownership plan (in shares)	1,100,000	1,200,000
Contribution expense under employee stock ownership plan	$ 20,300,000	$ 17,900,000	9,800,000
Employer Matching Contribution Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contribution plan, employer matching contribution percentage	100.00%
Defined contribution plans employee contribution percentage of eligible compensation matched by employer	5.00%
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]
Share-based compensation awards, vesting period	3 years
Unrecognized compensation expense	$ 18,100,000
Expected weighted-average period for cost recognition (in years)	1 year 10 months 24 days
Total fair value of shares vested	$ 15,100,000	$ 7,900,000	$ 4,300,000
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]
Share-based compensation awards, vesting period	36 months
Unrecognized compensation expense	$ 6,200,000
Expected weighted-average period for cost recognition (in years)	1 year 8 months 12 days
Stock Options \| Old National Bancorp
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incremental expense associated with conversion of stock awards	$ 0
Outside Director Stock Compensation Program \| Amended and Restated 2008 Incentive Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued (in shares)	41,000	19,000	25,000