SEGMENT REPORTING - Schedule of Segment Reporting, by Reportable Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Segment Reporting Information [Line Items]
Interest income	$ 234,302	$ 173,046	$ 620,244	$ 524,747
Interest expense	21,321	11,385	43,355	36,257
Net interest income	212,981	161,661	576,889	488,490
Provision for credit losses	17,652	(9,675)	38,807	(38,124)
Noninterest income	65,324	76,562	236,076	283,775
Noninterest expense
Salaries and employee benefits	78,697	79,671	244,523	261,161
Occupancy and equipment	12,983	11,979	38,456	34,572
Data processing and communications expenses	12,015	10,681	36,742	34,442
Other expenses	35,883	34,865	105,873	91,580
Total noninterest expense	139,578	137,196	425,594	421,755
Income before income tax expense	121,075	110,702	348,564	388,634
Income tax expense	28,520	29,022	84,245	93,665
Net income	92,555	81,680	264,319	294,969
Total assets	23,813,657	22,533,141	23,813,657	22,533,141	$ 23,858,321
Goodwill	1,023,071	928,005	1,023,071	928,005	1,012,620
Other intangible assets, net	110,903	60,396	110,903	60,396	$ 125,938
Banking Division
Segment Reporting Information [Line Items]
Interest income	164,095	110,708	435,229	332,347
Interest expense	(10,412)	(2,816)	(25,145)	(4,663)
Net interest income	174,507	113,524	460,374	337,010
Provision for credit losses	10,551	(9,578)	25,952	(37,431)
Noninterest income	23,269	17,896	68,102	50,805
Noninterest expense
Salaries and employee benefits	48,599	40,020	144,527	120,557
Occupancy and equipment	11,357	10,196	33,599	29,366
Data processing and communications expenses	10,779	9,159	32,872	29,640
Other expenses	22,974	21,723	64,142	60,196
Total noninterest expense	93,709	81,098	275,140	239,759
Income before income tax expense	93,516	59,900	227,384	185,487
Income tax expense	22,706	17,784	58,822	50,436
Net income	70,810	42,116	168,562	135,051
Total assets	16,980,520	16,070,583	16,980,520	16,070,583
Goodwill	958,573	863,507	958,573	863,507
Other intangible assets, net	101,225	47,768	101,225	47,768
Retail Mortgage Division
Segment Reporting Information [Line Items]
Interest income	40,389	33,390	111,276	97,674
Interest expense	21,106	12,101	51,919	34,868
Net interest income	19,283	21,289	59,357	62,806
Provision for credit losses	9,043	1,678	15,129	2,772
Noninterest income	38,584	55,555	158,028	222,250
Noninterest expense
Salaries and employee benefits	25,813	36,373	88,646	131,009
Occupancy and equipment	1,460	1,590	4,337	4,619
Data processing and communications expenses	1,082	1,357	3,377	4,338
Other expenses	11,641	11,675	37,098	27,502
Total noninterest expense	39,996	50,995	133,458	167,468
Income before income tax expense	8,828	24,171	68,798	114,816
Income tax expense	1,854	5,076	14,448	24,111
Net income	6,974	19,095	54,350	90,705
Total assets	4,402,221	4,247,967	4,402,221	4,247,967
Goodwill	0	0	0	0
Other intangible assets, net	0	0	0	0
Warehouse Lending Division
Segment Reporting Information [Line Items]
Interest income	12,490	9,093	27,779	28,408
Interest expense	5,511	381	7,653	1,070
Net interest income	6,979	8,712	20,126	27,338
Provision for credit losses	(1,836)	(291)	(1,191)	(591)
Noninterest income	1,516	1,037	3,958	3,350
Noninterest expense
Salaries and employee benefits	1,055	264	1,546	872
Occupancy and equipment	1	0	3	2
Data processing and communications expenses	43	59	138	176
Other expenses	209	200	639	263
Total noninterest expense	1,308	523	2,326	1,313
Income before income tax expense	9,023	9,517	22,949	29,966
Income tax expense	1,895	1,999	4,820	6,293
Net income	7,128	7,518	18,129	23,673
Total assets	955,711	740,809	955,711	740,809
Goodwill	0	0	0	0
Other intangible assets, net	0	0	0	0
SBA Division
Segment Reporting Information [Line Items]
Interest income	3,919	11,986	15,456	44,070
Interest expense	1,495	1,287	3,223	3,854
Net interest income	2,424	10,699	12,233	40,216
Provision for credit losses	52	(1,104)	(614)	(2,258)
Noninterest income	1,946	2,070	5,963	7,358
Noninterest expense
Salaries and employee benefits	1,412	1,320	3,999	3,639
Occupancy and equipment	82	116	262	354
Data processing and communications expenses	29	18	86	19
Other expenses	100	370	1,019	949
Total noninterest expense	1,623	1,824	5,366	4,961
Income before income tax expense	2,695	12,049	13,444	44,871
Income tax expense	566	2,530	2,823	9,423
Net income	2,129	9,519	10,621	35,448
Total assets	259,427	529,044	259,427	529,044
Goodwill	0	0	0	0
Other intangible assets, net	0	0	0	0
Premium  Finance  Division
Segment Reporting Information [Line Items]
Interest income	13,409	7,869	30,504	22,248
Interest expense	3,621	432	5,705	1,128
Net interest income	9,788	7,437	24,799	21,120
Provision for credit losses	(158)	(380)	(469)	(616)
Noninterest income	9	4	25	12
Noninterest expense
Salaries and employee benefits	1,818	1,694	5,805	5,084
Occupancy and equipment	83	77	255	231
Data processing and communications expenses	82	88	269	269
Other expenses	959	897	2,975	2,670
Total noninterest expense	2,942	2,756	9,304	8,254
Income before income tax expense	7,013	5,065	15,989	13,494
Income tax expense	1,499	1,633	3,332	3,402
Net income	5,514	3,432	12,657	10,092
Total assets	1,215,778	944,738	1,215,778	944,738
Goodwill	64,498	64,498	64,498	64,498
Other intangible assets, net	$ 9,678	$ 12,628	$ 9,678	$ 12,628