Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Examination [Line Items]
U.S. federal income tax rate, percent			21.00%	35.00%	35.00%
Tax cuts and jobs act description			The U.S. government enacted the Tax Act on December 22, 2017. The Tax Act makes broad and complex changes to the U.S. tax code that affected 2017, including, but not limited to, (1) requiring a one-time transition tax on certain unrepatriated earnings of foreign subsidiaries that is payable over eight years and (2) bonus depreciation that will allow for full expensing of qualified property. The Tax Act also establishes new tax laws that affected 2018, including, but not limited to, (1) reduction of the U.S. federal corporate tax rate; (2) the creation of the Base Erosion and Anti-Abuse (“BEAT”), a new minimum tax; (3) a general elimination of U.S. federal income taxes on dividends from foreign subsidiaries; (4) a new provision designed to tax Global Intangible Low-Taxed Income (“GILTI”), which allows for the possibility of using foreign tax credits and a deduction of up to 50 percent to offset the income tax liability (subject to some limitations); (5) the repeal of the domestic production activity deduction; (6) limitations on the deductibility of certain executive compensation; (7) limitations on the use of foreign tax credits to reduce the U.S. income tax liability; and (8) a new provision designed to allow a benefit for the foreign-derived intangible income (“FDII”). In 2018 we evaluated the effects and have determined what accounting policies needed to change and we have calculated the impact of the above provisions.
Remeasurement of deferred				$ 8,000,000
Provisional adjustment to deferred income tax expense				8,000,000
Adjustment to deferred income tax expense	$ 0
Transition tax expense		$ 100,000		1,500,000
Section 78 FTC				1,500,000
Tax reform FTC valuation allowance				1,500,000
Deferred tax assets, valuation allowance	3,172,000		$ 3,172,000	2,447,000
Operating loss carryforward, federal	497,000		497,000
Operating loss carryforward, state	205,000		205,000
Operating loss carryforward, foreign	990,000		990,000
Federal RD credit carryforward	0		0
State RD Credit Carryforward	318,000		318,000
Foreign RD credit carryforward	2,155,000		2,155,000
Undistributed earnings of foreign subsidiaries	7,914,000		7,914,000
Unrecognized tax benefit adjustment to income tax expense	4,995,000		4,995,000	4,403,000
Unrecognized tax benefits, income tax penalties and interest expense			199,000	246,000	$ 76,000
Unrecognized tax benefits, income tax penalties and interest accrued	1,445,000		1,445,000	$ 1,190,000
Foreign [Member]
Income Tax Examination [Line Items]
Tax credit carry forwards valuation allowance	2,155,000		$ 2,155,000
Operating loss carryforwards expiration date			Dec. 31, 2026
Foreign [Member] | Research and Development Credit [Member]
Income Tax Examination [Line Items]
Tax credit carryforward expiration date			Dec. 31, 2028
Foreign [Member] | China [Member]
Income Tax Examination [Line Items]
Operating loss valuation allowance	$ 112,000		$ 112,000
Federal [Member]
Income Tax Examination [Line Items]
Operating loss carryforwards expiration date			Dec. 31, 2032
State [Member]
Income Tax Examination [Line Items]
Operating loss carryforwards expiration date			Dec. 31, 2032
State [Member] | Research and Development Credit [Member]
Income Tax Examination [Line Items]
Tax credit carryforward expiration date			Dec. 21, 2024