SEGMENT REPORTING - Schedule of Segment Reporting, by Reportable Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Segment Reporting Information [Line Items]
Interest income	$ 347,323	$ 321,952	$ 676,775	$ 617,668
Interest expense	135,402	112,412	263,466	196,476
Net interest income	211,921	209,540	413,309	421,192
Provision for credit losses	18,773	45,516	39,878	95,245
Noninterest income	88,711	67,349	154,589	123,399
Noninterest expense
Salaries and employee benefits	88,201	81,336	171,131	162,246
Occupancy and equipment	12,559	12,522	25,444	25,508
Data processing and communications expenses	15,193	13,451	29,847	26,485
Other expenses	39,404	41,094	77,646	73,585
Total noninterest expense	155,357	148,403	304,068	287,824
Income before income tax expense	126,502	82,970	223,952	161,522
Income tax expense	35,717	20,335	58,855	38,466
Net income	90,785	62,635	165,097	123,056
Total assets	26,520,728	25,800,618	26,520,728	25,800,618	$ 25,203,699
Goodwill	1,015,646	1,015,646	1,015,646	1,015,646	1,015,646
Other intangible assets, net	79,120	96,800	79,120	96,800	$ 87,949
Banking Division
Segment Reporting Information [Line Items]
Interest income	243,857	230,199	478,979	442,789
Interest expense	70,320	56,427	140,974	91,732
Net interest income	173,537	173,772	338,005	351,057
Provision for credit losses	20,888	41,255	40,015	88,291
Noninterest income	37,527	26,128	63,890	50,631
Noninterest expense
Salaries and employee benefits	59,923	56,512	118,839	114,263
Occupancy and equipment	11,474	11,215	23,227	22,858
Data processing and communications expenses	13,756	11,944	26,940	23,778
Other expenses	24,614	27,976	49,061	47,421
Total noninterest expense	109,767	107,647	218,067	208,320
Income before income tax expense	80,409	50,998	143,813	105,077
Income tax expense	26,090	13,658	42,118	26,687
Net income	54,319	37,340	101,695	78,390
Total assets	18,933,072	18,532,088	18,933,072	18,532,088
Goodwill	951,148	951,148	951,148	951,148
Other intangible assets, net	74,605	89,335	74,605	89,335
Retail Mortgage Division
Segment Reporting Information [Line Items]
Interest income	59,001	52,867	114,100	101,456
Interest expense	35,259	31,450	67,071	60,012
Net interest income	23,742	21,417	47,029	41,444
Provision for credit losses	(2,882)	3,278	(550)	6,131
Noninterest income	50,145	39,808	88,910	70,866
Noninterest expense
Salaries and employee benefits	25,254	21,930	46,327	42,090
Occupancy and equipment	1,008	1,224	2,057	2,507
Data processing and communications expenses	1,276	1,397	2,642	2,466
Other expenses	13,397	11,859	25,927	23,606
Total noninterest expense	40,935	36,410	76,953	70,669
Income before income tax expense	35,834	21,537	59,536	35,510
Income tax expense	7,525	4,523	12,503	7,457
Net income	28,309	17,014	47,033	28,053
Total assets	5,100,837	4,921,354	5,100,837	4,921,354
Goodwill	0	0	0	0
Other intangible assets, net	0	0	0	0
Warehouse Lending Division
Segment Reporting Information [Line Items]
Interest income	19,380	18,960	35,863	35,574
Interest expense	13,088	12,794	23,543	23,708
Net interest income	6,292	6,166	12,320	11,866
Provision for credit losses	359	411	504	217
Noninterest income	1,028	1,404	1,768	1,884
Noninterest expense
Salaries and employee benefits	1,124	772	2,012	1,574
Occupancy and equipment	7	0	14	1
Data processing and communications expenses	59	44	84	90
Other expenses	298	223	535	425
Total noninterest expense	1,488	1,039	2,645	2,090
Income before income tax expense	5,473	6,120	10,939	11,443
Income tax expense	1,149	1,285	2,297	2,403
Net income	4,324	4,835	8,642	9,040
Total assets	1,089,263	1,152,690	1,089,263	1,152,690
Goodwill	0	0	0	0
Other intangible assets, net	0	0	0	0
Premium  Finance  Division
Segment Reporting Information [Line Items]
Interest income	25,085	19,926	47,833	37,849
Interest expense	16,735	11,741	31,878	21,024
Net interest income	8,350	8,185	15,955	16,825
Provision for credit losses	408	572	(91)	606
Noninterest income	11	9	21	18
Noninterest expense
Salaries and employee benefits	1,900	2,122	3,953	4,319
Occupancy and equipment	70	83	146	142
Data processing and communications expenses	102	66	181	151
Other expenses	1,095	1,036	2,123	2,133
Total noninterest expense	3,167	3,307	6,403	6,745
Income before income tax expense	4,786	4,315	9,664	9,492
Income tax expense	953	869	1,937	1,919
Net income	3,833	3,446	7,727	7,573
Total assets	1,397,556	1,194,486	1,397,556	1,194,486
Goodwill	64,498	64,498	64,498	64,498
Other intangible assets, net	$ 4,515	$ 7,465	$ 4,515	$ 7,465