FAIR VALUE - Carrying Amounts and Fair Values of Company's Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Financial assets:
Residential mortgage loans held for sale	$ 11,469	$ 39,409
Investments available-for-sale	1,244,335	1,465,896
Held-to-maturity debt securities	226,030	0
Loans, net of allowance	11,090,545	9,857,946
Accrued interest receivable	37,074	34,349
Financial liabilities:
Other deposits	10,749,486	10,624,731
Securities sold under retail repurchase agreements and federal funds purchased	206,287	141,086
Advances from FHLB	840,000	0
Subordinated debt	370,056	172,712
Carrying Amount
Financial assets:
Cash and cash equivalents	258,808	420,020
Residential mortgage loans held for sale	11,469	39,409
Investments available-for-sale	1,244,335	1,465,896
Held-to-maturity debt securities	265,648
Other investments	77,296	41,166
Loans, net of allowance	11,090,545	9,857,946
Interest rate swap agreements	19,546	5,880
Accrued interest receivable	37,074	34,349
Bank owned life insurance	152,065	147,528
Financial liabilities:
Time deposits	1,682,790	1,290,862
Other deposits	9,066,696	9,333,869
Securities sold under retail repurchase agreements and federal funds purchased	206,287	141,086
Advances from FHLB	840,000
Subordinated debt	370,056	172,712
Interest rate swap agreements	19,546	5,880
Accrued interest payable	6,957	1,516
Estimated Fair Value
Financial assets:
Cash and cash equivalents	258,808	420,020
Residential mortgage loans held for sale	11,469	39,409
Investments available-for-sale	1,244,335	1,465,896
Held-to-maturity debt securities	226,030
Other investments	77,296	41,166
Loans, net of allowance	10,765,365	9,964,924
Interest rate swap agreements	19,546	5,880
Accrued interest receivable	37,074	34,349
Bank owned life insurance	152,065	147,528
Financial liabilities:
Time deposits	1,646,655	1,292,598
Other deposits	9,066,696	9,333,869
Securities sold under retail repurchase agreements and federal funds purchased	206,287	141,086
Advances from FHLB	839,859
Subordinated debt	328,855	175,780
Interest rate swap agreements	19,546	5,880
Accrued interest payable	6,957	1,516
Quoted Prices in Active Markets for Identical Assets (Level 1) | Estimated Fair Value
Financial assets:
Cash and cash equivalents	258,808	420,020
Residential mortgage loans held for sale	0	0
Investments available-for-sale	0	0
Held-to-maturity debt securities	0
Other investments	0	0
Loans, net of allowance	0	0
Interest rate swap agreements	0	0
Accrued interest receivable	37,074	34,349
Bank owned life insurance	0	0
Financial liabilities:
Time deposits	0	0
Other deposits	9,066,696	9,333,869
Securities sold under retail repurchase agreements and federal funds purchased	0	0
Advances from FHLB	0
Subordinated debt	0	0
Interest rate swap agreements	0	0
Accrued interest payable	6,957	1,516
Significant Other Observable Inputs (Level 2) | Estimated Fair Value
Financial assets:
Cash and cash equivalents	0	0
Residential mortgage loans held for sale	11,469	39,409
Investments available-for-sale	1,244,335	1,465,896
Held-to-maturity debt securities	226,030
Other investments	77,296	41,166
Loans, net of allowance	0	0
Interest rate swap agreements	19,546	5,880
Accrued interest receivable	0	0
Bank owned life insurance	152,065	147,528
Financial liabilities:
Time deposits	1,646,655	1,292,598
Other deposits	0	0
Securities sold under retail repurchase agreements and federal funds purchased	206,287	141,086
Advances from FHLB	839,859
Subordinated debt	0	0
Interest rate swap agreements	19,546	5,880
Accrued interest payable	0	0
Significant Unobservable Inputs (Level 3) | Estimated Fair Value
Financial assets:
Cash and cash equivalents	0	0
Residential mortgage loans held for sale	0	0
Investments available-for-sale	0	0
Held-to-maturity debt securities	0
Other investments	0	0
Loans, net of allowance	10,765,365	9,964,924
Interest rate swap agreements	0	0
Accrued interest receivable	0	0
Bank owned life insurance	0	0
Financial liabilities:
Time deposits	0	0
Other deposits	0	0
Securities sold under retail repurchase agreements and federal funds purchased	0	0
Advances from FHLB	0
Subordinated debt	328,855	175,780
Interest rate swap agreements	0	0
Accrued interest payable	$ 0	$ 0