Investments (Narrative) (Details) - USD ($)	3 Months Ended	12 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2015	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Technology investments in non-consolidated affiliates (less than)			20.00%
Technology investments in non-consolidated affiliates	$ 4,100,000			$ 3,850,000
Equity investment losses were considered to be other than temporary	$ 0	$ 0

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 8A
-URI http://asc.fasb.org/extlink&oid=109979856&loc=SL6284422-111562

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