Investments Investments in private companies (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized Gain (Loss) on Marketable Securities, Cost Method Investments, and Other Investments	$ (1,629,000)	$ (758,000)
Investment Owned, at Fair Value	3,090,000	4,870,000
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized Gain (Loss) on Marketable Securities, Cost Method Investments, and Other Investments	600,000
Equity Method Investment, Other than Temporary Impairment	$ 1,000,000	$ 2,000,000