ALLOWANCE FOR LOAN LOSSES: ALLOWANCE FOR LOAN LOSSES: (Details 4) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Impaired, Troubled Debt Restructuring [Roll Forward]
January 1,	$ 8,565	$ 9,860	$ 14,758
Added	613	492	1,090
Charged Off	(430)	(391)	(117)
Payments	(1,714)	(1,396)	(5,871)
December 31,	7,034	8,565	9,860
Commercial
Financing Receivable, Impaired, Troubled Debt Restructuring [Roll Forward]
January 1,	3,386	3,584	8,955
Added	0	0	0
Charged Off	0	0	0
Payments	(677)	(198)	(5,371)
December 31,	2,709	3,386	3,584
Residential
Financing Receivable, Impaired, Troubled Debt Restructuring [Roll Forward]
January 1,	4,447	5,593	5,189
Added	227	123	748
Charged Off	(289)	(321)	(65)
Payments	(774)	(948)	(279)
December 31,	3,611	4,447	5,593
Consumer
Financing Receivable, Impaired, Troubled Debt Restructuring [Roll Forward]
January 1,	732	683	614
Added	386	369	342
Charged Off	(141)	(70)	(52)
Payments	(263)	(250)	(221)
December 31,	$ 714	$ 732	$ 683