Stock Purchase Plans (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Aug. 27, 2015
Stock Purchase Plans
Common shares issued for employee stock purchase plan	$ 34,000	$ 23,000	$ 73,000	$ 67,000
Options, outstanding (in shares)	1,000,000	917,000	1,000,000	917,000	914,000	3,000
Director compensation plan, expense	$ 63,000	$ 72,000	$ 193,000	$ 240,000
Non-Employee Director Compensation Plan
Stock Purchase Plans
Number of shares allowed to be purchased (in shares)	100,000		100,000
Maximum percentage of base compensation			100.00%
Current percentage of base compensation			50.00%
Options, outstanding (in shares)	42,191		42,191
Director compensation plan (in shares)			7,560	9,968
Director compensation plan, expense			$ 193,000	$ 240,000
Employee Stock
Stock Purchase Plans
Number of shares allowed to be purchased (in shares)	1,500,000		1,500,000
Purchase price of the shares with respect to market value (as a percent)			95.00%
Maximum percentage of base compensation			15.00%
Maximum market value			$ 12,000
Number of shares issued under the plan (in shares)			3,120	2,960