SEGMENT REPORTING - Schedule of Segment Reporting, by Reportable Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Interest income	$ 330,553	$ 234,302	$ 948,221	$ 620,244
Interest expense	122,802	21,321	319,278	43,355
Net interest income	207,751	212,981	628,943	576,889
Provision for credit losses	24,459	17,652	119,704	38,807
Noninterest income	63,181	65,324	186,580	236,076
Noninterest expense
Salaries and employee benefits	81,898	78,697	244,144	244,523
Occupancy and equipment	12,745	12,983	38,253	38,456
Data processing and communications expenses	12,973	12,015	39,458	36,742
Other expenses	33,830	35,883	107,415	105,873
Total noninterest expense	141,446	139,578	429,270	425,594
Income before income tax expense	105,027	121,075	266,549	348,564
Income tax expense	24,912	28,520	63,378	84,245
Net income	80,115	92,555	203,171	264,319
Total assets	25,697,830	23,813,657	25,697,830	23,813,657	$ 25,053,286
Goodwill	1,015,646	1,023,071	1,015,646	1,023,071	1,015,646
Other intangible assets, net	92,375	110,903	92,375	110,903	106,194
Banking Division
Segment Reporting Information [Line Items]
Interest income	228,448	164,095	661,947	435,229
Interest expense	60,853	(10,412)	147,583	(25,145)
Net interest income	167,595	174,507	514,364	460,374
Provision for credit losses	20,833	10,551	108,804	25,952
Noninterest income	26,245	23,269	74,795	68,102
Noninterest expense
Salaries and employee benefits	56,226	48,599	167,864	144,527
Occupancy and equipment	11,437	11,357	34,218	33,599
Data processing and communications expenses	11,786	10,779	35,481	32,872
Other expenses	20,274	22,974	66,940	64,142
Total noninterest expense	99,723	93,709	304,503	275,140
Income before income tax expense	73,284	93,516	175,852	227,384
Income tax expense	18,283	22,706	44,443	58,822
Net income	55,001	70,810	131,409	168,562
Total assets	18,369,102	16,980,520	18,369,102	16,980,520
Goodwill	951,148	958,573	951,148	958,573	951,100
Other intangible assets, net	85,648	101,225	85,648	101,225
Retail Mortgage Division
Segment Reporting Information [Line Items]
Interest income	54,532	40,389	155,988	111,276
Interest expense	31,727	21,106	91,739	51,919
Net interest income	22,805	19,283	64,249	59,357
Provision for credit losses	2,399	9,043	8,530	15,129
Noninterest income	35,691	38,584	106,557	158,028
Noninterest expense
Salaries and employee benefits	21,231	25,813	63,321	88,646
Occupancy and equipment	1,182	1,460	3,689	4,337
Data processing and communications expenses	1,052	1,082	3,518	3,377
Other expenses	12,153	11,641	35,759	37,098
Total noninterest expense	35,618	39,996	106,287	133,458
Income before income tax expense	20,479	8,828	55,989	68,798
Income tax expense	4,301	1,854	11,758	14,448
Net income	16,178	6,974	44,231	54,350
Total assets	4,980,246	4,402,221	4,980,246	4,402,221
Goodwill	0	0	0	0
Other intangible assets, net	0	0	0	0
Warehouse Lending Division
Segment Reporting Information [Line Items]
Interest income	19,357	12,490	54,931	27,779
Interest expense	13,349	5,511	37,057	7,653
Net interest income	6,008	6,979	17,874	20,126
Provision for credit losses	(589)	(1,836)	(372)	(1,191)
Noninterest income	662	1,516	2,546	3,958
Noninterest expense
Salaries and employee benefits	924	1,055	2,498	1,546
Occupancy and equipment	1	1	2	3
Data processing and communications expenses	30	43	120	138
Other expenses	219	209	644	639
Total noninterest expense	1,174	1,308	3,264	2,326
Income before income tax expense	6,085	9,023	17,528	22,949
Income tax expense	1,278	1,895	3,681	4,820
Net income	4,807	7,128	13,847	18,129
Total assets	859,517	955,711	859,517	955,711
Goodwill	0	0	0	0
Other intangible assets, net	0	0	0	0
SBA Division
Segment Reporting Information [Line Items]
Interest income	4,766	3,919	14,056	15,456
Interest expense	2,804	1,495	7,806	3,223
Net interest income	1,962	2,424	6,250	12,233
Provision for credit losses	1,677	52	1,997	(614)
Noninterest income	579	1,946	2,660	5,963
Noninterest expense
Salaries and employee benefits	1,209	1,412	3,834	3,999
Occupancy and equipment	36	82	113	262
Data processing and communications expenses	32	29	115	86
Other expenses	157	100	912	1,019
Total noninterest expense	1,434	1,623	4,974	5,366
Income before income tax expense	(570)	2,695	1,939	13,444
Income tax expense	(120)	566	407	2,823
Net income	(450)	2,129	1,532	10,621
Total assets	264,953	259,427	264,953	259,427
Goodwill	0	0	0	0
Other intangible assets, net	0	0	0	0
Premium  Finance  Division
Segment Reporting Information [Line Items]
Interest income	23,450	13,409	61,299	30,504
Interest expense	14,069	3,621	35,093	5,705
Net interest income	9,381	9,788	26,206	24,799
Provision for credit losses	139	(158)	745	(469)
Noninterest income	4	9	22	25
Noninterest expense
Salaries and employee benefits	2,308	1,818	6,627	5,805
Occupancy and equipment	89	83	231	255
Data processing and communications expenses	73	82	224	269
Other expenses	1,027	959	3,160	2,975
Total noninterest expense	3,497	2,942	10,242	9,304
Income before income tax expense	5,749	7,013	15,241	15,989
Income tax expense	1,170	1,499	3,089	3,332
Net income	4,579	5,514	12,152	12,657
Total assets	1,224,012	1,215,778	1,224,012	1,215,778
Goodwill	64,498	64,498	64,498	64,498	$ 64,500
Other intangible assets, net	$ 6,727	$ 9,678	$ 6,727	$ 9,678