GOODWILL AND OTHER INTANGIBLE ASSETS - Goodwill and Accumulated Impairment Charges (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Goodwill prior to impairment	$ 176,578
Cumulative goodwill impairment	(118,971)
Goodwill	57,607	$ 57,607
Goodwill acquired	0	0
Holding Company and Eliminations
Goodwill [Line Items]
Goodwill prior to impairment	75,162
Cumulative goodwill impairment	(75,162)
Goodwill	0
Private Banking
Goodwill [Line Items]
Goodwill prior to impairment	34,281
Cumulative goodwill impairment	(34,281)
Goodwill	0
Wealth Management and Trust
Goodwill [Line Items]
Goodwill prior to impairment	67,135
Cumulative goodwill impairment	(9,528)
Goodwill	$ 57,607	$ 57,607