MERGERS AND ACQUISITIONS - Narrative (Details) $ / shares in Units, $ in Thousands				1 Months Ended	3 Months Ended	7 Months Ended
	Mar. 01, 2025 USD ($) state $ / shares shares	Feb. 28, 2025 USD ($)	Apr. 01, 2024 USD ($) $ / shares shares	Mar. 31, 2025 bankingCenter	Jun. 30, 2025 USD ($)	Sep. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)
Business Combination, Contingent Consideration [Line Items]
Number of full-service locations | bankingCenter				79
Number of states in which entity operates | state	10
Preferred stock redemption price per share (in dollars per share) | $ / shares	$ 1,000
Fair value adjustments						$ (1,800)
Goodwill						$ 383,323	$ 333,695
CrossFirst
Business Combination, Contingent Consideration [Line Items]
Total consideration paid	$ 808,980	$ 6,000
Goodwill	49,553
Fair value of financial assets acquired	4,700,000
Gross contractual amounts of acquired receivables	$ 4,790,000
CrossFirst | Common | CrossFirst | SSARs
Business Combination, Contingent Consideration [Line Items]
Shares received for each share owned (in shares) | shares	0.6675
M&M
Business Combination, Contingent Consideration [Line Items]
Shares received for each share owned (in shares) | shares			5.7294
Total consideration paid			$ 49,575
Goodwill			$ 15,897
Per share cash consideration entitled, Cash Election (in dollars per share) | $ / shares			$ 117.74
Consideration transferred per share in cash, Mixed Election (in dollars per share) | $ / shares			$ 34.55
Mixed consideration (in shares) | shares			4.0481
Business combination consideration, number of shares (in shares) | shares			1,429,304
Cash			$ 12,200
Consideration transferred per share in cash, Share Election (in dollars per share) | $ / shares			$ 5.3966
Consideration transferred per share in shares, Share Election (in shares) | shares			5.4668
Cash consideration received (in dollars per share) | $ / shares			$ 117.74
Fractional shares, payment rate (in dollars per share) | $ / shares			$ 23.32
Additional consideration transferred			$ 3,000
Number of shares redeemed ( in shares) | shares			300
Business acquisition fair value adjustment, deferred taxes					$ 100