SEGMENT REPORTING - Schedule of Segment Reporting, by Reportable Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Interest income	$ 295,716	$ 183,374
Interest expense	84,064	10,830
Net interest income	211,652	172,544
Provision for credit losses	49,729	6,231
Noninterest income	56,050	86,911
Noninterest expense
Salaries and employee benefits	80,910	84,281
Occupancy and equipment	12,986	12,727
Data processing and communications expenses	13,034	12,572
Other expenses	32,491	34,240
Total noninterest expense	139,421	143,820
Income before income tax expense	78,552	109,404
Income tax expense	18,131	27,706
Net income	60,421	81,698
Total assets	26,088,384	23,560,292	$ 25,053,286
Goodwill	1,015,646	1,022,345	1,015,646
Other intangible assets, net	101,488	120,757	$ 106,194
Banking Division
Segment Reporting Information [Line Items]
Interest income	208,215	129,290
Interest expense	32,887	(4,455)
Net interest income	175,328	133,745
Provision for credit losses	47,140	5,226
Noninterest income	23,898	21,364
Noninterest expense
Salaries and employee benefits	56,442	49,195
Occupancy and equipment	11,606	11,074
Data processing and communications expenses	11,797	11,230
Other expenses	19,023	20,045
Total noninterest expense	98,868	91,544
Income before income tax expense	53,218	58,339
Income tax expense	12,848	16,996
Net income	40,370	41,343
Total assets	18,870,145	17,409,973
Goodwill	951,148	957,847
Other intangible assets, net	93,285	109,604
Retail Mortgage Division
Segment Reporting Information [Line Items]
Interest income	48,589	32,832
Interest expense	28,562	13,537
Net interest income	20,027	19,295
Provision for credit losses	2,853	1,587
Noninterest income	31,058	61,649
Noninterest expense
Salaries and employee benefits	20,160	31,614
Occupancy and equipment	1,283	1,471
Data processing and communications expenses	1,069	1,172
Other expenses	11,747	12,645
Total noninterest expense	34,259	46,902
Income before income tax expense	13,973	32,455
Income tax expense	2,934	6,815
Net income	11,039	25,640
Total assets	4,879,135	4,197,613
Goodwill	0	0
Other intangible assets, net	0	0
Warehouse Lending Division
Segment Reporting Information [Line Items]
Interest income	16,614	6,813
Interest expense	10,914	366
Net interest income	5,700	6,447
Provision for credit losses	(194)	(222)
Noninterest income	480	1,401
Noninterest expense
Salaries and employee benefits	802	283
Occupancy and equipment	1	1
Data processing and communications expenses	46	47
Other expenses	202	218
Total noninterest expense	1,051	549
Income before income tax expense	5,323	7,521
Income tax expense	1,118	1,579
Net income	4,205	5,942
Total assets	936,169	703,558
Goodwill	0	0
Other intangible assets, net	0	0
SBA Division
Segment Reporting Information [Line Items]
Interest income	4,375	6,780
Interest expense	2,418	769
Net interest income	1,957	6,011
Provision for credit losses	(104)	(143)
Noninterest income	605	2,491
Noninterest expense
Salaries and employee benefits	1,309	1,271
Occupancy and equipment	37	99
Data processing and communications expenses	37	28
Other expenses	422	380
Total noninterest expense	1,805	1,778
Income before income tax expense	861	6,867
Income tax expense	181	1,442
Net income	680	5,425
Total assets	272,844	313,219
Goodwill	0	0
Other intangible assets, net	0	0
Premium  Finance  Division
Segment Reporting Information [Line Items]
Interest income	17,923	7,659
Interest expense	9,283	613
Net interest income	8,640	7,046
Provision for credit losses	34	(217)
Noninterest income	9	6
Noninterest expense
Salaries and employee benefits	2,197	1,918
Occupancy and equipment	59	82
Data processing and communications expenses	85	95
Other expenses	1,097	952
Total noninterest expense	3,438	3,047
Income before income tax expense	5,177	4,222
Income tax expense	1,050	874
Net income	4,127	3,348
Total assets	1,130,091	935,929
Goodwill	64,498	64,498
Other intangible assets, net	$ 8,203	$ 11,153