6. Loans and Allowance for Loan Losses: Financing Receivable, Allowance for Credit Loss (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Period-end amount allocated to: Total	$ 201,521		$ 179,949
Loans and Leases Receivable, Net of Deferred Income	24,212,084		25,725,700
Total
Beginning balance	180,000	$ 300,000
Provision for loan losses	20,000	(30,000)
Charge-offs	(5,000)	(1,000)
Recoveries	7,000	3,000
Net charge-offs	2,000	2,000
Ending balance	202,000	273,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	31,000		0
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	171,000		180,000
Period-end amount allocated to: Total	202,000		180,000
Loans, ending balance: Loans individually evaluated for impairment	1,302,000		1,277,000
Loans, ending balance: Loans collectively evaluated for impairment	22,910,000		24,448,000
Loans and Leases Receivable, Net of Deferred Income	24,212,000		25,725,000
Commercial And Industrial
Beginning balance	7,000	68,000
Provision for loan losses	0	(6,000)
Charge-offs	0	0
Recoveries	1,000	1,000
Net charge-offs	1,000	1,000
Ending balance	8,000	63,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		0
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	8,000		7,000
Loans, ending balance: Loans individually evaluated for impairment	76,000		76,000
Loans, ending balance: Loans collectively evaluated for impairment	2,022,000		1,722,000
Commercial And Industrial | Thousand
Period-end amount allocated to: Total	8,000		7,000
Loans and Leases Receivable, Net of Deferred Income	2,098,000		1,798,000
Commercial Real Estate Portfolio Segment
Beginning balance	155,000	179,000
Provision for loan losses	3,000	(8,000)
Charge-offs	0	0
Recoveries	0	0
Net charge-offs	0	0
Ending balance	158,000	171,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	31,000		0
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	127,000		155,000
Loans, ending balance: Loans individually evaluated for impairment	1,226,000		1,201,000
Loans, ending balance: Loans collectively evaluated for impairment	18,530,000		20,188,000
Commercial Real Estate Portfolio Segment | Thousand
Period-end amount allocated to: Total	158,000		155,000
Loans and Leases Receivable, Net of Deferred Income	19,756,000		21,389,000
Consumer Real Estate
Beginning balance	10,000	10,000
Provision for loan losses	(4,000)	(3,000)
Charge-offs	0	0
Recoveries	0	1,000
Net charge-offs	0	1,000
Ending balance	6,000	8,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		0
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	6,000		10,000
Loans, ending balance: Loans individually evaluated for impairment	0		0
Loans, ending balance: Loans collectively evaluated for impairment	1,606,000		1,729,000
Consumer Real Estate | Thousand
Period-end amount allocated to: Total	6,000		10,000
Loans and Leases Receivable, Net of Deferred Income	1,606,000		1,729,000
Consumer And Other Loans
Beginning balance	8,000	11,000
Provision for loan losses	1,000	0
Charge-offs	(5,000)	(1,000)
Recoveries	6,000	1,000
Net charge-offs	1,000	0
Ending balance	10,000	11,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		0
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	10,000		8,000
Loans, ending balance: Loans individually evaluated for impairment	0		0
Loans, ending balance: Loans collectively evaluated for impairment	752,000		809,000
Consumer And Other Loans | Thousand
Period-end amount allocated to: Total	10,000		8,000
Loans and Leases Receivable, Net of Deferred Income	752,000		809,000
Unallocated Financing Receivables
Beginning balance	0	32,000
Provision for loan losses	20,000	(12,000)
Charge-offs	0	0
Recoveries	0	0
Net charge-offs	0	0
Ending balance	20,000	$ 20,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	0		0
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	20,000		0
Loans, ending balance: Loans individually evaluated for impairment	0		0
Loans, ending balance: Loans collectively evaluated for impairment	0		0
Unallocated Financing Receivables | Thousand
Period-end amount allocated to: Total	20,000		0
Loans and Leases Receivable, Net of Deferred Income	$ 0		$ 0