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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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- Definition

Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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STOCK-BASED COMPENSATION - Stock Settled Appreciation Rights Narrative (Details) - shares		3 Months Ended	12 Months Ended
	Mar. 01, 2025	Mar. 31, 2025	Dec. 31, 2024
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Weighted-average remaining contractual life, options outstanding		1 year 7 months 17 days	1 year 10 months 13 days
SSARs
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Weighted-average remaining contractual life, options outstanding		5 years 4 months 28 days
SSARs \| CrossFirst \| Common \| CrossFirst
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares received for each share owned (in shares)	0.6675
Omnibus Incentive 2018 Plan \| SSARs
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Vesting period		7 years
Weighted-average remaining contractual life, options outstanding		5 years 4 months 24 days
Period over which cost will be recognized		3 years 2 months 12 days
Omnibus Incentive 2018 Plan \| SSARs \| Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation, expiration period		10 years
Omnibus Incentive 2018 Plan \| SSARs \| Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation, expiration period		15 years