SEGMENT REPORTING - Schedule of Segment Reporting, by Reportable Business Segments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Interest income	$ 333,778	$ 329,452
Interest expense	111,939	128,064
Net interest income	221,839	201,388
Provision for credit losses	21,892	21,105
Noninterest income	64,023	65,878
Noninterest expense
Salaries and employee benefits	86,615	82,930
Occupancy and equipment	10,677	12,885
Data processing and communications expenses	14,855	14,654
Other expenses	38,887	38,242
Total noninterest expense	151,034	148,711
Income before income tax expense	112,936	97,450
Income tax expense	25,001	23,138
Net income	87,935	74,312
Total assets	26,514,940	25,655,445	$ 26,262,050
Goodwill	1,015,646	1,015,646	1,015,646
Other intangible assets, net	66,658	83,527	$ 70,761
Banking Division
Segment Reporting Information [Line Items]
Interest income	233,319	235,122
Interest expense	49,106	70,654
Net interest income	184,213	164,468
Provision for credit losses	16,420	19,127
Noninterest income	28,724	26,363
Noninterest expense
Salaries and employee benefits	62,716	58,916
Occupancy and equipment	9,804	11,753
Data processing and communications expenses	13,391	13,184
Other expenses	25,685	24,447
Total noninterest expense	111,596	108,300
Income before income tax expense	84,921	63,404
Income tax expense	19,154	16,028
Net income	65,767	47,376
Total assets	19,291,312	18,553,964
Goodwill	951,148	951,148
Other intangible assets, net	64,330	78,275
Retail Mortgage Division
Segment Reporting Information [Line Items]
Interest income	57,932	55,099
Interest expense	36,088	31,812
Net interest income	21,844	23,287
Provision for credit losses	5,191	2,332
Noninterest income	34,729	38,765
Noninterest expense
Salaries and employee benefits	20,995	21,073
Occupancy and equipment	829	1,049
Data processing and communications expenses	1,297	1,366
Other expenses	11,963	12,530
Total noninterest expense	35,084	36,018
Income before income tax expense	16,298	23,702
Income tax expense	3,423	4,978
Net income	12,875	18,724
Total assets	4,762,848	4,971,058
Goodwill	0	0
Other intangible assets, net	0	0
Warehouse Lending Division
Segment Reporting Information [Line Items]
Interest income	15,200	16,483
Interest expense	9,298	10,455
Net interest income	5,902	6,028
Provision for credit losses	(175)	145
Noninterest income	554	740
Noninterest expense
Salaries and employee benefits	552	888
Occupancy and equipment	7	7
Data processing and communications expenses	38	25
Other expenses	270	237
Total noninterest expense	867	1,157
Income before income tax expense	5,764	5,466
Income tax expense	1,210	1,148
Net income	4,554	4,318
Total assets	911,361	897,460
Goodwill	0	0
Other intangible assets, net	0	0
Premium  Finance  Division
Segment Reporting Information [Line Items]
Interest income	27,327	22,748
Interest expense	17,447	15,143
Net interest income	9,880	7,605
Provision for credit losses	456	(499)
Noninterest income	16	10
Noninterest expense
Salaries and employee benefits	2,352	2,053
Occupancy and equipment	37	76
Data processing and communications expenses	129	79
Other expenses	969	1,028
Total noninterest expense	3,487	3,236
Income before income tax expense	5,953	4,878
Income tax expense	1,214	984
Net income	4,739	3,894
Total assets	1,549,419	1,232,963
Goodwill	64,498	64,498
Other intangible assets, net	$ 2,328	$ 5,252