Repurchase of Common Stock (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Notes to Financial Statements
Number of shares repurchased, 2020 program	630	0	630	0
Cost of shares repurchased allocated to retained earnings, 2020 program	$ 2,969	$ 0	$ 2,969	$ 0
Cost of shares repurchased allocated to capital, 2020 program	310	0	310	0
Cost of shares repurchased, total, 2020 program	$ 3,279	$ 0	$ 3,279	$ 0
Number of shares repurchased, 2008 program	0	0	978	356
Cost of shares repurchased allocated to retained earnings, 2008 program	$ 0	$ 0	$ 5,760	$ 1,946
Cost of shares repurchased allocated to capital, 2008 program	0	0	480	175
Cost of shares repurchased, total, 2008 program	$ 0	$ 0	$ 6,240	$ 2,121