INCOME TAXES: (Details textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Federal statutory income tax rate (percent)	35.00%
Part of unrecognized tax benefits	$ 825	$ 698	$ 513	$ 589
Increase (decrease) in interest and penalities	4	4	17
Income tax examination, penalties and interest accrued	$ 40	$ 31	$ 27