GOODWILL AND INTANGIBLE ASSETS: (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 21,205	$ 10,836
Accumulated Amortization	10,562	9,639
Core deposit intangible
Finite-Lived Intangible Assets [Line Items]
Gross Amount	21,205	10,836
Accumulated Amortization	$ 10,562	$ 9,639