Income Taxes (Details 2) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Taxes
Income tax expense at the statutory federal income tax rate	$ 8,070,000	$ 8,078,000	$ 9,065,000
Increase (decrease) resulting from:
State income taxes	1,027,000	839,000	978,000
R&D tax credits	(1,703,000)	(1,589,000)	(1,470,000)
Foreign-derived intangible income deduction	(2,091,000)	(1,051,000)	(1,700,000)
Excess tax benefit from stock compensation	(185,000)	(81,000)	(412,000)
Uncertain tax positions	0	(450,000)	(42,000)
Other, net	256,000	606,000	(12,000)
Provision for Income Taxes	$ 5,374,000	$ 6,352,000	$ 6,407,000