LOANS - Schedule of Industry and Rate Sensitivity (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	$ 2,074,475	$ 2,239,930
Computer Programming, Data Processing & Other Computer Related Services
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	375,103	483,142
Management & Public Relations Services
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	291,581	300,869
Industrial Inorganic Chemicals
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	156,782	156,391
Public Warehousing & Storage
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	120,473	132,397
Metal Cans & Shipping Containers
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	115,907	115,670
Surgical, Medical & Dental Instruments & Supplies
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	82,831	83,161
Electronic Components & Accessories
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	78,257	78,129
Engineering, Architectural, and Surveying
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	77,156	77,308
Offices & Clinics of Doctors of Medicine
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	74,481	104,781
Miscellaneous Health & Allied Services, not elsewhere classified
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	70,295	77,163
Insurance Agents, Brokers and Service
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	65,624	67,193
Research, Development & Testing Services
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	62,218	62,008
Miscellaneous Food Preparations
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	59,009	58,857
Telephone Communications
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	58,694	58,450
Miscellaneous Equipment Rental & Leasing
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	49,641	49,587
Electric Work
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	40,390	41,128
Petroleum and Petroleum Products
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	33,836	33,890
Medical & Dental Laboratories
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	30,763	30,711
Schools & Educational Services, not elsewhere classified
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	29,183	29,040
Home Health Care Services
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	28,669	28,587
Metal Forgings & Stampings
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	27,689	27,523
Legal Services
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	26,358	26,399
Grocery Stores
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	22,906	22,895
Coating, Engraving and Allied Services
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	19,500	19,484
Miscellaneous Business Services
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	14,996	12,980
Chemicals & Allied Products
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	14,667	14,686
Mailing, Reproduction, Commercial Art and Photography and Stenographic
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	12,917	12,733
Drugs
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	12,622	12,942
Machinery, Equipment & Supplies
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	11,839	12,096
Offices and Clinics of Other Health Practitioners
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	$ 10,088	$ 9,730