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Concentration Risk Schedule of Revenue Concentration (Details) - Product Concentration Risk [Member]	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Equity Assets [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	44.00%	42.00%
Money Market Assets [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	39.00%	41.00%
Fixed-Income Assets [Member]
Concentration Risk [Line Items]
Concentration Risk, Percentage	17.00%	17.00%

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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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.

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