Income Taxes - Additional Information (Details) - USD ($)		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Contingency [Line Items]
Income tax provisions		$ 168,000	$ 166,000	$ 96,000
Undistributed earnings of foreign subsidiaries		371,000
Unrecognized deferred tax liability		74,000
Increase in valuation allowance		905,000	106,000
Accumulated federal tax losses		100,000,000	97,000,000
Accumulated state tax losses		779,000	794,000
Tax benefit record from stock option		0	0
Net operating loss carryforwards	[1],[2]	34,287,000	33,783,000
Research and development credit carry-forwards		$ 8,500,000	7,500,000
Federal tax credit carryforward expiration year		2023
Unrecognized tax benefits		$ 2,597,000	$ 1,878,000	$ 1,732,000	$ 1,599,000
Accrued interest and penalties related to unrecognized tax benefits		0
Accounting Standards Update 2016-09 [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards		$ 727,000

[1] Carryforwards are presented net of associated tax contingencies

[2] During the current period, we recorded an increase to the NOL and an increase to the valuation allowance of $727,000 as a result of the adoption of ASU 2016-09, "Improvements to Employee Share-Based Payment Accounting."