Income Taxes (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax [Line Items]
Percentage of dividends-received-deduction for foreign-source dividends received from 10%-or-more owned foreign corporations	100.00%
Benefit from eliminating previously recorded deferred tax liability for undistributed earnings	$ 2,700,000
Minimum ownership percentage in foreign corporations for foreign-source dividends deduction	10.00%
Valuation allowance (as a percent)	26.10%	(141.90%)	(26.10%)
Earnings and dividends of foreign affiliate (as a percent)	0.00%	32.20%	(28.90%)
Change in liability for uncertain tax positions	$ 28,000	$ 5,000	$ 14,000
Valuation allowance	$ 1,606,000	1,086,000
Percentage of change in corporate income tax rate due to write-down of deferred tax assets	21.00%
Increase (decrease) in valuation allowance	$ (520,000)	(9,600,000)
Research & Development tax credits	3,900,000
Deferred tax assets, operating loss carryforwards, domestic	8,900,000
Deferred tax assets, operating loss carryforwards, foreign	0	463,000
Cash payments for income taxes, net of refunds received	40,000	144,000	$ 16,000
Excess tax benefit from the exercise of stock options	227,000
Deferred tax liability for subsidiary's undistributed earnings	0	$ 2,520,000
Accounting Standards Update 2016-09 [Member]
Income Tax [Line Items]
Excess tax benefit from the exercise of stock options	$ 227,000