SEGMENT REPORTING - Schedule of Financial Information with Respect to Company's Reportable Business Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Interest income	$ 1,280,435	$ 893,886	$ 703,112
Interest expense	445,391	92,860	47,785
Net interest income	835,044	801,026	655,327
Provision for credit losses	142,656	71,697	(35,365)
Noninterest income	242,828	284,424	365,544
Noninterest expense
Salaries and employee benefits	320,110	319,719	337,776
Occupancy and equipment expenses	51,450	51,361	48,066
Data processing and communications expenses	53,486	49,228	45,976
Other expenses	153,235	140,347	128,306
Total noninterest expense	578,281	560,655	560,124
Income before income tax expense	356,935	453,098	496,112
Income tax expense	87,830	106,558	119,199
Net income	269,105	346,540	376,913
Total assets	25,203,699	25,053,286	23,858,321
Goodwill	1,015,646	1,015,646	1,012,620
Other intangible assets, net	87,949	106,194	125,938
Banking Division
Segment Reporting Information [Line Items]
Interest income	894,514	628,459	449,955
Interest expense	214,036	(17,824)	(7,627)
Net interest income	680,478	646,283	457,582
Provision for credit losses	129,998	61,898	(32,866)
Noninterest income	98,864	91,550	69,664
Noninterest expense
Salaries and employee benefits	223,551	196,823	157,079
Occupancy and equipment expenses	46,083	45,081	41,065
Data processing and communications expenses	48,021	43,957	39,802
Other expenses	100,029	85,953	84,244
Total noninterest expense	417,684	371,814	322,190
Income before income tax expense	231,660	304,121	237,922
Income tax expense	61,649	75,367	64,446
Net income	170,011	228,754	173,476
Total assets	18,041,865	17,848,972	17,537,221
Goodwill	951,148	951,148	948,122
Other intangible assets, net	81,959	97,254	114,048
Retail Mortgage Division
Segment Reporting Information [Line Items]
Interest income	212,106	155,533	130,140
Interest expense	123,804	76,339	47,422
Net interest income	88,302	79,194	82,718
Provision for credit losses	9,535	12,351	2,947
Noninterest income	137,145	182,039	281,900
Noninterest expense
Salaries and employee benefits	80,317	107,810	167,796
Occupancy and equipment expenses	4,899	5,579	6,206
Data processing and communications expenses	4,836	4,580	5,551
Other expenses	47,393	48,224	38,295
Total noninterest expense	137,445	166,193	217,848
Income before income tax expense	78,467	82,689	143,823
Income tax expense	16,478	17,364	30,203
Net income	61,989	65,325	113,620
Total assets	4,916,753	4,739,612	4,231,767
Goodwill	0	0	0
Other intangible assets, net	0	0	0
Warehouse Lending Division
Segment Reporting Information [Line Items]
Interest income	71,110	43,521	36,784
Interest expense	47,271	16,794	1,383
Net interest income	23,839	26,727	35,401
Provision for credit losses	(440)	(1,074)	(514)
Noninterest income	3,475	4,537	4,603
Noninterest expense
Salaries and employee benefits	2,794	1,973	1,130
Occupancy and equipment expenses	5	4	3
Data processing and communications expenses	171	187	232
Other expenses	873	830	490
Total noninterest expense	3,843	2,994	1,855
Income before income tax expense	23,911	29,344	38,663
Income tax expense	5,021	6,162	8,120
Net income	18,890	23,182	30,543
Total assets	825,415	1,016,192	760,546
Goodwill	0	0	0
Other intangible assets, net	0	0	0
SBA Division
Segment Reporting Information [Line Items]
Interest income	18,925	19,850	56,597
Interest expense	10,507	5,126	5,062
Net interest income	8,418	14,724	51,535
Provision for credit losses	2,791	(349)	(2,921)
Noninterest income	3,313	6,265	9,360
Noninterest expense
Salaries and employee benefits	4,848	5,305	4,856
Occupancy and equipment expenses	149	360	475
Data processing and communications expenses	134	116	47
Other expenses	723	1,387	1,594
Total noninterest expense	5,854	7,168	6,972
Income before income tax expense	3,086	14,170	56,844
Income tax expense	648	2,976	11,937
Net income	2,438	11,194	44,907
Total assets	249,761	256,077	419,040
Goodwill	0	0	0
Other intangible assets, net	0	0	0
Premium Finance Division
Segment Reporting Information [Line Items]
Interest income	83,780	46,523	29,636
Interest expense	49,773	12,425	1,545
Net interest income	34,007	34,098	28,091
Provision for credit losses	772	(1,129)	(2,011)
Noninterest income	31	33	17
Noninterest expense
Salaries and employee benefits	8,600	7,808	6,915
Occupancy and equipment expenses	314	337	317
Data processing and communications expenses	324	388	344
Other expenses	4,217	3,953	3,683
Total noninterest expense	13,455	12,486	11,259
Income before income tax expense	19,811	22,774	18,860
Income tax expense	4,034	4,689	4,493
Net income	15,777	18,085	14,367
Total assets	1,169,905	1,192,433	909,747
Goodwill	64,498	64,498	64,498
Other intangible assets, net	$ 5,990	$ 8,940	$ 11,890