LOANS AND CREDIT QUALITY - Loan and Lease Receivable Portfolio (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Mar. 31, 2026	Dec. 31, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024
Loans held for investment
Total loan receivables before allowance for credit losses	$ 13,576,196		$ 14,176,936
Allowance for credit losses on loans	(152,601)	$ (156,796)	(153,319)	$ (68,334)	$ (75,515)	$ (88,558)
Net loan receivables	13,423,595		14,023,617
Commercial and industrial
Loans held for investment
Total loan receivables before allowance for credit losses	439,814		482,170
Allowance for credit losses on loans	(10,150)	(8,860)	(8,417)	(3,456)	(4,297)	(4,869)
Commercial real estate
Loans held for investment
Allowance for credit losses on loans	(124,277)	(120,758)	(114,326)	(33,599)	(34,995)	(35,097)
Commercial real estate \| Multifamily
Loans held for investment
Total loan receivables before allowance for credit losses	5,223,356		5,355,252
Commercial real estate \| Non-owner occupied
Loans held for investment
Total loan receivables before allowance for credit losses	1,614,883		1,740,277
Commercial real estate \| Owner occupied
Loans held for investment
Total loan receivables before allowance for credit losses	512,474		689,079
Commercial real estate \| Construction and land development
Loans held for investment
Total loan receivables before allowance for credit losses	360,668		493,992
Residential real estate
Loans held for investment
Total loan receivables before allowance for credit losses	4,107,867		3,970,803
Allowance for credit losses on loans	(7,759)	(13,621)	(13,294)	(4,977)	(4,763)	(4,656)
Auto
Loans held for investment
Total loan receivables before allowance for credit losses	510,232		791,012
Allowance for credit losses on loans	(8,420)	(11,446)	(15,003)	(23,867)	(28,935)	(41,282)
Other consumer
Loans held for investment
Total loan receivables before allowance for credit losses	806,902		654,351
Allowance for credit losses on loans	$ (1,995)	$ (2,111)	$ (2,279)	$ (2,435)	$ (2,525)	$ (2,654)