Amortization period of cost capitalized in obtaining or fulfilling contract with customer, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Basis of Presentation and Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue from External Customer [Line Items]
Revenue	$ 19,895		$ 18,204	$ 37,886	$ 32,922
Additions to tax positions of prior years		$ 547
Income tax penalties and interest accrued		55
Bill and Hold Arrangement
Revenue from External Customer [Line Items]
Revenue				$ 6,100
Minimum
Revenue from External Customer [Line Items]
Amortization period of capitalized contract costs	1 year			1 year
Tax Year 2017
Revenue from External Customer [Line Items]
Additions to tax positions of prior years		168
Tax Year 2016
Revenue from External Customer [Line Items]
Additions to tax positions of prior years		149
Tax Year 2015
Revenue from External Customer [Line Items]
Additions to tax positions of prior years		$ 230