6. Loans and Allowance for Loan Losses: Financing Receivable, Allowance for Credit Loss (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Period-end amount allocated to: Total	$ 180,359		$ 180,359		$ 179,949
Loans and Leases Receivable, Net of Deferred Income	22,887,785		22,887,785		25,725,700
Total
Beginning balance	202,000	$ 273,000	180,000	$ 300,000
Provision for loan losses	5,000	(46,000)	25,000	(76,000)
Charge-offs	(30,000)	(2,000)	(35,000)	(3,000)
Recoveries	3,000	27,000	10,000	31,000
Net charge-offs	(27,000)	25,000	(25,000)	28,000
Ending balance	180,000	252,000	180,000	252,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	31,000		31,000		0
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	149,000		149,000		180,000
Period-end amount allocated to: Total	180,000		180,000		180,000
Loans, ending balance: Loans individually evaluated for impairment	1,278,000		1,278,000		1,277,000
Loans, ending balance: Loans collectively evaluated for impairment	21,610,000		21,610,000		24,448,000
Loans and Leases Receivable, Net of Deferred Income	22,888,000		22,888,000		25,725,000
Commercial And Industrial
Beginning balance	8,000	63,000	7,000	68,000
Provision for loan losses	4,000	10,000	4,000	4,000
Charge-offs	(10,000)	0	(10,000)	0
Recoveries	1,000	1,000	2,000	2,000
Net charge-offs	(9,000)	1,000	(8,000)	2,000
Ending balance	3,000	74,000	3,000	74,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		0		0
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	3,000		3,000		7,000
Loans, ending balance: Loans individually evaluated for impairment	76,000		76,000		76,000
Loans, ending balance: Loans collectively evaluated for impairment	1,647,000		1,647,000		1,722,000
Commercial And Industrial | Thousand
Period-end amount allocated to: Total	3,000		3,000		7,000
Loans and Leases Receivable, Net of Deferred Income	1,723,000		1,723,000		1,798,000
Commercial Real Estate Portfolio Segment
Beginning balance	158,000	171,000	155,000	179,000
Provision for loan losses	8,000	(26,000)	11,000	(34,000)
Charge-offs	(18,000)	0	(18,000)	0
Recoveries	2,000	25,000	2,000	25,000
Net charge-offs	(16,000)	25,000	(16,000)	25,000
Ending balance	150,000	170,000	150,000	170,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	31,000		31,000		0
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	119,000		119,000		155,000
Loans, ending balance: Loans individually evaluated for impairment	1,202,000		1,202,000		1,201,000
Loans, ending balance: Loans collectively evaluated for impairment	17,925,000		17,925,000		20,188,000
Commercial Real Estate Portfolio Segment | Thousand
Period-end amount allocated to: Total	150,000		150,000		155,000
Loans and Leases Receivable, Net of Deferred Income	19,127,000		19,127,000		21,389,000
Consumer Real Estate
Beginning balance	6,000	8,000	10,000	10,000
Provision for loan losses	(2,000)	0	(6,000)	(3,000)
Charge-offs	0	0	0	0
Recoveries	0	0	0	1,000
Net charge-offs	0	0	0	1,000
Ending balance	4,000	8,000	4,000	8,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		0		0
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	4,000		4,000		10,000
Loans, ending balance: Loans individually evaluated for impairment	0		0		0
Loans, ending balance: Loans collectively evaluated for impairment	1,321,000		1,321,000		1,729,000
Consumer Real Estate | Thousand
Period-end amount allocated to: Total	4,000		4,000		10,000
Loans and Leases Receivable, Net of Deferred Income	1,321,000		1,321,000		1,729,000
Consumer And Other Loans
Beginning balance	10,000	11,000	8,000	11,000
Provision for loan losses	0	0	1,000	0
Charge-offs	(2,000)	(2,000)	(7,000)	(3,000)
Recoveries	0	1,000	6,000	3,000
Net charge-offs	(2,000)	(1,000)	(1,000)	0
Ending balance	8,000	10,000	8,000	10,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		0		0
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	8,000		8,000		8,000
Loans, ending balance: Loans individually evaluated for impairment	0		0		0
Loans, ending balance: Loans collectively evaluated for impairment	717,000		717,000		809,000
Consumer And Other Loans | Thousand
Period-end amount allocated to: Total	8,000		8,000		8,000
Loans and Leases Receivable, Net of Deferred Income	717,000		717,000		809,000
Unallocated Financing Receivables
Beginning balance	20,000	20,000	0	32,000
Provision for loan losses	(5,000)	(30,000)	15,000	(43,000)
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Net charge-offs	0	0	0	0
Ending balance	15,000	$ 10,000	15,000	$ 10,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		0		0
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	15,000		15,000		0
Loans, ending balance: Loans individually evaluated for impairment	0		0		0
Loans, ending balance: Loans collectively evaluated for impairment	0		0		0
Unallocated Financing Receivables | Thousand
Period-end amount allocated to: Total	15,000		15,000		0
Loans and Leases Receivable, Net of Deferred Income	$ 0		$ 0		$ 0