BUSINESS COMBINATION Narrative (Details) - USD ($) $ in Thousands	Nov. 01, 2019	Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Goodwill		$ 373,121	$ 373,121	$ 339,154
AltaPacific Bank [Member]
Business Acquisition [Line Items]
Business Combination, Acquired Receivables, Non-Credit-Impaired, Fair Value	$ 328,200
Business Combination, Acquired Receivables, Non-Credit-Impaired, Discount	$ 5,300
Business Acquisition, Effective Date of Acquisition	Nov. 01, 2019
Percentage of voting interest acquired	100.00%
Business Combination, Ratio of Shares Acquired to Shares Exchanged	0.2712
Assets acquired	$ 425,669
Loans receivable (contractual amount of $338.2 million)	332,355
Deposits	313,374
Core deposit intangible	4,610
Goodwill	$ 33,967
Business combination, CDI acquired useful life	10 years
Business Combination, Acquired Receivables, Non-Credit-Impaired	$ 333,500
Credit related discount	$ 5,800