REGULATORY MATTERS - Company's and Bank's Actual Capital Amounts and Ratios (Details) $ in Thousands	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Company
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Leverage Ratio (tier 1 capital to average assets) Actual Amount	$ 2,185,694	$ 1,897,725
Tier 1 Leverage Ratio (tier 1 capital to average assets) Actual Ratio	0.0936	0.0863
Tier 1 Leverage Ratio (tier 1 capital to average assets) For Capital Adequacy Purposes Amount	$ 933,928	$ 879,079
Tier 1 Leverage Ratio (tier 1 capital to average assets) For Capital Adequacy Purposes Ratio	0.0400	0.0400
CET1 Ratio (common equity tier 1 capital to risk weighted assets) Actual Amount	$ 2,185,694	$ 1,897,725
CET1 Ratio (common equity tier 1 capital to risk weighted assets) Actual Ratio	9.86%	10.46%
CET1 Ratio (common equity tier 1 capital to risk weighted assets) Adequacy Purposes Amount	$ 1,551,305	$ 1,270,535
CET1 Ratio (common equity tier 1 capital to risk weighted assets) Adequacy Purposes Ratio	7.00%	7.00%
Tier 1 Capital Ratio (tier 1 capital to risk weighted assets) Actual Amount	$ 2,185,694	$ 1,897,725
Tier 1 Capital Ratio (tier 1 capital to risk weighted assets) Actual Ratio	0.0986	0.1046
Tier 1 Capital Ratio (tier 1 capital to risk weighted assets) For Capital Adequacy Purposes Amount	$ 1,883,727	$ 1,542,792
Tier 1 Capital Ratio (tier 1 capital to risk weighted assets) For Capital Adequacy Purposes Ratio	0.0850	0.0850
Total Capital Ratio (total capital to risk weighted assets) Actual Amount	$ 2,859,680	$ 2,500,287
Total Capital Ratio (total capital to risk weighted assets) Actual Ratio	0.1290	0.1378
Total Capital Ratio (total capital to risk weighted assets) For Capital Adequacy Purposes Amount	$ 2,326,957	$ 1,905,802
Total Capital Ratio (total capital to risk weighted assets) For Capital Adequacy Purposes Ratio	0.1050	0.1050
Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Leverage Ratio (tier 1 capital to average assets) Actual Amount	$ 2,464,589	$ 2,084,465
Tier 1 Leverage Ratio (tier 1 capital to average assets) Actual Ratio	0.1056	0.0950
Tier 1 Leverage Ratio (tier 1 capital to average assets) For Capital Adequacy Purposes Amount	$ 933,284	$ 877,891
Tier 1 Leverage Ratio (tier 1 capital to average assets) For Capital Adequacy Purposes Ratio	0.0400	0.0400
Tier 1 Leverage Ratio (tier 1 capital to average assets) To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 1,166,605	$ 1,097,364
Tier 1 Leverage Ratio (tier 1 capital to average assets) To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	0.0500	0.0500
CET1 Ratio (common equity tier 1 capital to risk weighted assets) Actual Amount	$ 2,464,589	$ 2,084,465
CET1 Ratio (common equity tier 1 capital to risk weighted assets) Actual Ratio	11.12%	11.50%
CET1 Ratio (common equity tier 1 capital to risk weighted assets) Adequacy Purposes Amount	$ 1,551,185	$ 1,268,622
CET1 Ratio (common equity tier 1 capital to risk weighted assets) Adequacy Purposes Ratio	7.00%	7.00%
CET1 Ratio (common equity tier 1 capital to risk weighted assets) To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 1,440,386	$ 1,178,007
CET1 Ratio (common equity tier 1 capital to risk weighted assets) To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	6.50%	6.50%
Tier 1 Capital Ratio (tier 1 capital to risk weighted assets) Actual Amount	$ 2,464,589	$ 2,084,465
Tier 1 Capital Ratio (tier 1 capital to risk weighted assets) Actual Ratio	0.1112	0.1150
Tier 1 Capital Ratio (tier 1 capital to risk weighted assets) For Capital Adequacy Purposes Amount	$ 1,883,581	$ 1,540,470
Tier 1 Capital Ratio (tier 1 capital to risk weighted assets) For Capital Adequacy Purposes Ratio	0.0850	0.0850
Tier 1 Capital Ratio (tier 1 capital to risk weighted assets) To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 1,772,782	$ 1,449,854
Tier 1 Capital Ratio (tier 1 capital to risk weighted assets) To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	0.0800	0.0800
Total Capital Ratio (total capital to risk weighted assets) Actual Amount	$ 2,720,253	$ 2,255,699
Total Capital Ratio (total capital to risk weighted assets) Actual Ratio	0.1228	0.1245
Total Capital Ratio (total capital to risk weighted assets) For Capital Adequacy Purposes Amount	$ 2,326,777	$ 1,902,934
Total Capital Ratio (total capital to risk weighted assets) For Capital Adequacy Purposes Ratio	0.1050	0.1050
Total Capital Ratio (total capital to risk weighted assets) To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 2,215,978	$ 1,812,318
Total Capital Ratio (total capital to risk weighted assets) To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	0.1000	0.1000