Fair Value Measurements (Detail Textuals) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, primarily include money market funds	$ 52,266	$ 51,232	$ 46,421	$ 43,985
Fair value on recurring basis | Corporate debt securities | Fair Value Measurement, Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investments	916	869
Fair value on recurring basis | Money market funds (included in cash and cash equivalents) | Fair Value Measurement, Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents, primarily include money market funds	$ 49,300	$ 43,000