LOANS - Schedule of Industry and Rate Sensitivity (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	$ 2,239,930	$ 2,144,850
Computer programming, data processing & other computer related services
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	483,142	394,193
Management and public relations services
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	300,869	339,179
Industrial Inorganic Chemical
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	156,391	0
Public warehousing and storage
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	132,397	107,029
Metal cans & shipping containers
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	115,670	118,456
Offices and clinics of doctors of medicine
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	104,781	106,993
Surgical, medical, and dental instruments and supplies
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	83,161	102,182
Electronic components & accessories
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	78,129	24,000
Engineering, architectural & surveying
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	77,308	124,201
Miscellaneous Industrial & Commercial
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	77,163	78,908
Insurance agents, brokers and services
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	67,193	75,410
Research, development and testing services
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	62,008	45,610
Miscellaneous Food Preparations
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	58,857	0
Telephone communications
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	58,450	61,210
Miscellaneous equipment rental and leasing
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	49,587	49,776
Electrical work
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	41,128	43,175
Petroleum and petroleum products
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	33,890	24,923
Medical and dental laboratories
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	30,711	41,344
Schools and educational services, not elsewhere classified
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	29,040	19,586
Home health care services
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	28,587	29,361
Metal Forgings and Stampings
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	27,523	0
Legal Services
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	26,399	0
Grocery stores
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	22,895	23,248
Coating, engraving and allied services
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	19,484	47,249
Chemicals & Allied Products
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	14,686	15,002
Miscellaneous business services
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	12,980	164,033
Drugs
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	12,942	15,923
Mailing, reproduction, commercial art and photography, and stenographic
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	12,733	14,755
Machinery, Equipment & Supplies
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	12,096	0
Offices of clinics and other health practitioners
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	9,730	10,098
Nonferrous foundries (castings)
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	0	30,191
Motor vehicles and motor vehicle parts and supplies
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	0	28,815
Miscellaneous plastic products
Schedule of Held-to-maturity Securities [Line Items]
Corporate debt	$ 0	$ 10,000