SEGMENT REPORTING - Schedule of Financial Information with Respect to Company's Reportable Business Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Interest income	$ 893,886	$ 703,112	$ 726,503
Interest expense	92,860	47,785	88,750
Net interest income	801,026	655,327	637,753
Provision for credit losses	71,697	(35,365)	145,380
Noninterest income	284,424	365,544	446,500
Noninterest expense
Salaries and employee benefits	319,719	337,776	360,278
Occupancy and equipment expenses	51,361	48,066	52,349
Data processing and communications expenses	49,228	45,976	46,017
Other expenses	140,347	128,306	139,985
Total noninterest expense	560,655	560,124	598,629
Income before income tax expense	453,098	496,112	340,244
Income tax expense	106,558	119,199	78,256
Net income	346,540	376,913	261,988
Total assets	25,053,286	23,858,321	20,438,638
Goodwill	1,015,646	1,012,620	928,005
Other intangible assets, net	106,194	125,938	71,974
Banking Division
Segment Reporting Information [Line Items]
Interest income	628,459	449,955	499,031
Interest expense	(17,824)	(7,627)	27,800
Net interest income	646,283	457,582	471,231
Provision for credit losses	61,898	(32,866)	125,136
Noninterest income	91,550	69,664	63,165
Noninterest expense
Salaries and employee benefits	196,823	157,079	160,430
Occupancy and equipment expenses	45,081	41,065	44,939
Data processing and communications expenses	43,957	39,802	39,040
Other expenses	85,953	84,244	105,965
Total noninterest expense	371,814	322,190	350,374
Income before income tax expense	304,121	237,922	58,886
Income tax expense	75,367	64,446	19,138
Net income	228,754	173,476	39,748
Total assets	17,848,972	17,537,221	14,250,780
Goodwill	951,148	948,122	863,507
Other intangible assets, net	97,254	114,048	57,129
Retail Mortgage Division
Segment Reporting Information [Line Items]
Interest income	155,533	130,140	129,951
Interest expense	76,339	47,422	47,592
Net interest income	79,194	82,718	82,359
Provision for credit losses	12,351	2,947	15,850
Noninterest income	182,039	281,900	370,256
Noninterest expense
Salaries and employee benefits	107,810	167,796	184,765
Occupancy and equipment expenses	5,579	6,206	6,710
Data processing and communications expenses	4,580	5,551	6,275
Other expenses	48,224	38,295	28,155
Total noninterest expense	166,193	217,848	225,905
Income before income tax expense	82,689	143,823	210,860
Income tax expense	17,364	30,203	44,286
Net income	65,325	113,620	166,574
Total assets	4,739,612	4,231,767	3,395,811
Goodwill	0	0	0
Other intangible assets, net	0	0	0
Warehouse Lending Division
Segment Reporting Information [Line Items]
Interest income	43,521	36,784	26,522
Interest expense	16,794	1,383	2,631
Net interest income	26,727	35,401	23,891
Provision for credit losses	(1,074)	(514)	2,562
Noninterest income	4,537	4,603	3,864
Noninterest expense
Salaries and employee benefits	1,973	1,130	981
Occupancy and equipment expenses	4	3	4
Data processing and communications expenses	187	232	270
Other expenses	830	490	176
Total noninterest expense	2,994	1,855	1,431
Income before income tax expense	29,344	38,663	23,762
Income tax expense	6,162	8,120	5,004
Net income	23,182	30,543	18,758
Total assets	1,016,192	760,546	922,071
Goodwill	0	0	0
Other intangible assets, net	0	0	0
SBA Division
Segment Reporting Information [Line Items]
Interest income	19,850	56,597	40,334
Interest expense	5,126	5,062	7,244
Net interest income	14,724	51,535	33,090
Provision for credit losses	(349)	(2,921)	2,719
Noninterest income	6,265	9,360	9,200
Noninterest expense
Salaries and employee benefits	5,305	4,856	6,893
Occupancy and equipment expenses	360	475	391
Data processing and communications expenses	116	47	33
Other expenses	1,387	1,594	1,832
Total noninterest expense	7,168	6,972	9,149
Income before income tax expense	14,170	56,844	30,422
Income tax expense	2,976	11,937	6,389
Net income	11,194	44,907	24,033
Total assets	256,077	419,040	1,088,611
Goodwill	0	0	0
Other intangible assets, net	0	0	0
Premium Finance Division
Segment Reporting Information [Line Items]
Interest income	46,523	29,636	30,665
Interest expense	12,425	1,545	3,483
Net interest income	34,098	28,091	27,182
Provision for credit losses	(1,129)	(2,011)	(887)
Noninterest income	33	17	15
Noninterest expense
Salaries and employee benefits	7,808	6,915	7,209
Occupancy and equipment expenses	337	317	305
Data processing and communications expenses	388	344	399
Other expenses	3,953	3,683	3,857
Total noninterest expense	12,486	11,259	11,770
Income before income tax expense	22,774	18,860	16,314
Income tax expense	4,689	4,493	3,439
Net income	18,085	14,367	12,875
Total assets	1,192,433	909,747	781,365
Goodwill	64,498	64,498	64,498
Other intangible assets, net	$ 8,940	$ 11,890	$ 14,845