PORTFOLIO LOANS - Schedule of Activity on the Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Activity in the allowance for loan losses
ACL beginning balance	$ 83,404	$ 91,740
Provision for credit losses and Day 2 Provision for Credit Losses	42,452	5,038
Provision for credit losses	19
Charged-off	(31,835)	(5,460)
Recoveries	406	244
ACL ending balance	195,210	91,562
CrossFirst
Activity in the allowance for loan losses
Day 1 PCD	100,783
Provision for credit losses and Day 2 Provision for Credit Losses	42,433
Commercial loans \| C&I and other commercial
Activity in the allowance for loan losses
ACL beginning balance	21,589	21,256
Provision for credit losses and Day 2 Provision for Credit Losses		10,125
Provision for credit losses	623
Charged-off	(31,221)	(5,218)
Recoveries	96	44
ACL ending balance	89,304	26,207
Commercial loans \| C&I and other commercial \| CrossFirst
Activity in the allowance for loan losses
Day 1 PCD	75,569
Provision for credit losses and Day 2 Provision for Credit Losses	22,648
Commercial loans \| CRE
Activity in the allowance for loan losses
ACL beginning balance	32,301	35,465
Provision for credit losses and Day 2 Provision for Credit Losses		(1,864)
Provision for credit losses	(393)
Charged-off	(253)	(96)
Recoveries	131	0
ACL ending balance	68,478	33,505
Commercial loans \| CRE \| CrossFirst
Activity in the allowance for loan losses
Day 1 PCD	21,588
Provision for credit losses and Day 2 Provision for Credit Losses	15,104
Commercial loans \| Real estate construction
Activity in the allowance for loan losses
ACL beginning balance	3,345	5,163
Provision for credit losses and Day 2 Provision for Credit Losses		(491)
Provision for credit losses	311
Charged-off	0	0
Recoveries	10	41
ACL ending balance	8,689	4,713
Commercial loans \| Real estate construction \| CrossFirst
Activity in the allowance for loan losses
Day 1 PCD	2,112
Provision for credit losses and Day 2 Provision for Credit Losses	2,911
Retail loans \| CRE
Activity in the allowance for loan losses
ACL beginning balance	23,711	26,298
Provision for credit losses and Day 2 Provision for Credit Losses		(2,093)
Provision for credit losses	(503)
Charged-off	0	(52)
Recoveries	133	128
ACL ending balance	26,399	24,281
Retail loans \| CRE \| CrossFirst
Activity in the allowance for loan losses
Day 1 PCD	1,430
Provision for credit losses and Day 2 Provision for Credit Losses	1,628
Retail loans \| Retail other
Activity in the allowance for loan losses
ACL beginning balance	2,458	3,558
Provision for credit losses and Day 2 Provision for Credit Losses		(639)
Provision for credit losses	(19)
Charged-off	(361)	(94)
Recoveries	36	31
ACL ending balance	2,340	$ 2,856
Retail loans \| Retail other \| CrossFirst
Activity in the allowance for loan losses
Day 1 PCD	84
Provision for credit losses and Day 2 Provision for Credit Losses	$ 142

Financing Receivable, Excluding Accrued Interest, Credit Loss Expense (Reversal), Excluding Business Acquisition

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479344/326-20-45-1

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- Definition

Amount, excluding accrued interest, of increase in allowance for credit loss on financing receivable from recovery. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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- Definition

Amount, excluding accrued interest, of decrease in allowance for credit loss on financing receivable from writeoff. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-6

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- Definition

Amount, excluding accrued interest, of credit loss expense (reversal of expense) on financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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- Definition

Amount, excluding accrued interest, of allowance for credit loss at acquisition date of financing receivable purchased with credit deterioration. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 19
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-19

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-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

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