Repurchase of Common Stock (Details)	12 Months Ended
	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Aug. 10, 2020 USD ($)
Notes to Financial Statements
Number of shares repurchased, 2020 program	857	0
Cost of shares repurchased allocated to retained earnings, 2020 program	$ 4,071	$ 0
Cost of shares repurchased allocated to capital, 2020 program	422	0
Cost of shares repurchased, total, 2020 program	$ 4,493	$ 0
Number of shares repurchased, 2008 program	978	383
Cost of shares repurchased allocated to retained earnings, 2008 program	$ 5,760	$ 2,108
Cost of shares repurchased allocated to capital, 2008 program	480	188
Cost of shares repurchased, total, 2008 program	6,240	$ 2,296
Dollar amount authorized under 2020 program			$ 5,000,000
Dollar amount available under 2020 program	$ 4,995,507