Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019
Income Taxes
Deferred tax assets, operating loss carryforwards		$ 5,128,000	$ 4,724,000
Credit carry-forwards		17,401,000	15,964,000
Deferred tax asset valuation allowance		8,320,000	8,011,000
Foreign tax credit carry-forwards		7,467,000
Research and development credits		7,502,000
Tax Cuts and Jobs Act, income tax benefit	$ 348,000
Unrecognized tax benefits		3,128,000
Uncertain tax positions to be settled in next 12 months		900,000
Accrued for interest and penalties related to uncertain income tax		$ 301,000	$ 707,000
Tax years subject to examination		2017 through 2019
Earliest Tax Year
Income Taxes
Open tax year		2008
Latest Tax Year
Income Taxes
Open tax year		2019
Operating Loss Carryforward | Minimum
Income Taxes
Tax credit carryforward, expiration year		2021
Operating Loss Carryforward | Maximum
Income Taxes
Tax credit carryforward, expiration year		2040
Foreign Tax Credit Carryforward
Income Taxes
Valuation allowance against tax credit carryforwards		$ 180,000
Foreign Tax Credit Carryforward | Minimum
Income Taxes
Tax credit carryforward, expiration year		2028
Foreign Tax Credit Carryforward | Maximum
Income Taxes
Tax credit carryforward, expiration year		2029
Research Tax Credit Carryforward
Income Taxes
Valuation allowance against tax credit carryforwards		$ 0
Research Tax Credit Carryforward | Minimum
Income Taxes
Tax credit carryforward, expiration year		2021
Research Tax Credit Carryforward | Maximum
Income Taxes
Tax credit carryforward, expiration year		2040