SEGMENT REPORTING - Schedule of Segment Reporting, by Reportable Business Segments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Segment Reporting Information [Line Items]
Interest income	$ 1,378,284	$ 1,280,435	$ 893,886
Interest expense	529,094	445,391	92,860
Net interest income	849,190	835,044	801,026
Provision for credit losses	58,793	142,656	71,697
Noninterest income	293,257	242,828	284,424
Noninterest expense
Salaries and employee benefits	347,641	320,110	319,719
Occupancy and equipment expenses	48,784	51,450	51,361
Data processing and communications expenses	59,699	53,486	49,228
Other expenses	151,670	153,235	140,347
Total noninterest expense	607,794	578,281	560,655
Income before income tax expense	475,860	356,935	453,098
Income tax expense	117,175	87,830	106,558
Net income	358,685	269,105	346,540
Total assets	26,262,050	25,203,699	25,053,286
Goodwill	1,015,646	1,015,646	1,015,646
Other intangible assets, net	70,761	87,949	106,194
Banking Division
Segment Reporting Information [Line Items]
Interest income	962,918	913,439	648,309
Interest expense	271,201	224,543	(12,698)
Net interest income	691,717	688,896	661,007
Provision for credit losses	60,434	132,789	61,549
Noninterest income	121,972	102,177	97,815
Noninterest expense
Salaries and employee benefits	243,795	228,399	202,128
Occupancy and equipment expenses	44,568	46,232	45,441
Data processing and communications expenses	54,121	48,155	44,073
Other expenses	96,049	100,752	87,340
Total noninterest expense	438,533	423,538	378,982
Income before income tax expense	314,722	234,746	318,291
Income tax expense	83,503	62,297	78,343
Net income	231,219	172,449	239,948
Total assets	18,954,256	18,291,626	18,105,049
Goodwill	951,148	951,148	951,148
Other intangible assets, net	67,721	81,959	97,254
Retail Mortgage Division
Segment Reporting Information [Line Items]
Interest income	236,670	212,106	155,533
Interest expense	142,374	123,804	76,339
Net interest income	94,296	88,302	79,194
Provision for credit losses	(2,799)	9,535	12,351
Noninterest income	167,031	137,145	182,039
Noninterest expense
Salaries and employee benefits	92,436	80,317	107,810
Occupancy and equipment expenses	3,965	4,899	5,579
Data processing and communications expenses	5,048	4,836	4,580
Other expenses	50,209	47,393	48,224
Total noninterest expense	151,658	137,445	166,193
Income before income tax expense	112,468	78,467	82,689
Income tax expense	23,618	16,478	17,364
Net income	88,850	61,989	65,325
Total assets	4,828,842	4,916,753	4,739,612
Goodwill	0	0	0
Other intangible assets, net	0	0	0
Warehouse Lending Division
Segment Reporting Information [Line Items]
Interest income	75,264	71,110	43,521
Interest expense	48,492	47,271	16,794
Net interest income	26,772	23,839	26,727
Provision for credit losses	275	(440)	(1,074)
Noninterest income	4,209	3,475	4,537
Noninterest expense
Salaries and employee benefits	3,216	2,794	1,973
Occupancy and equipment expenses	26	5	4
Data processing and communications expenses	160	171	187
Other expenses	976	873	830
Total noninterest expense	4,378	3,843	2,994
Income before income tax expense	26,328	23,911	29,344
Income tax expense	5,529	5,021	6,162
Net income	20,799	18,890	23,182
Total assets	983,229	825,415	1,016,192
Goodwill	0	0	0
Other intangible assets, net	0	0	0
Premium Finance Division
Segment Reporting Information [Line Items]
Interest income	103,432	83,780	46,523
Interest expense	67,027	49,773	12,425
Net interest income	36,405	34,007	34,098
Provision for credit losses	883	772	(1,129)
Noninterest income	45	31	33
Noninterest expense
Salaries and employee benefits	8,194	8,600	7,808
Occupancy and equipment expenses	225	314	337
Data processing and communications expenses	370	324	388
Other expenses	4,436	4,217	3,953
Total noninterest expense	13,225	13,455	12,486
Income before income tax expense	22,342	19,811	22,774
Income tax expense	4,525	4,034	4,689
Net income	17,817	15,777	18,085
Total assets	1,495,723	1,169,905	1,192,433
Goodwill	64,498	64,498	64,498
Other intangible assets, net	$ 3,040	$ 5,990	$ 8,940