Business and Summary of Significant Accounting Policies - Concentrations (Details)	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
One distributor \| Revenue \| Customer concentration risk
Concentration Risk [Line Items]
Concentration risk, percentage	44.00%	45.00%
One distributor \| Accounts receivable \| Customer concentration risk
Concentration Risk [Line Items]
Concentration risk, percentage	45.00%	46.00%
Channel network \| Revenue \| Sales method risk
Concentration Risk [Line Items]
Concentration risk, percentage	90.00%	86.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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