ALLOWANCE FOR LOAN LOSSES: ALLOWANCE FOR LOAN LOSSES: (Details 4) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Impaired, Troubled Debt Restructuring [Roll Forward]
January 1,	$ 4,194	$ 4,806	$ 7,034
Added	996	570	1,279
Charged Off	(164)	(105)	(153)
Payments	(820)	(1,077)	(3,354)
December 31,	4,206	4,194	4,806
Commercial
Financing Receivable, Impaired, Troubled Debt Restructuring [Roll Forward]
January 1,	11	145	2,709
Added	0	0	0
Charged Off	0	0	0
Payments	(11)	(134)	(2,564)
December 31,	0	11	145
Residential
Financing Receivable, Impaired, Troubled Debt Restructuring [Roll Forward]
January 1,	3,485	4,043	3,611
Added	692	195	984
Charged Off	(6)	(24)	(16)
Payments	(582)	(729)	(536)
December 31,	3,589	3,485	4,043
Consumer
Financing Receivable, Impaired, Troubled Debt Restructuring [Roll Forward]
January 1,	698	618	714
Added	304	375	295
Charged Off	(158)	(81)	(137)
Payments	(227)	(214)	(254)
December 31,	$ 617	$ 698	$ 618