Fair Value Measurements (Detail Textuals) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, primarily include money market funds	$ 43,507	$ 72,660	$ 75,418	$ 71,074
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	1,362	2,754
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 and cash equivalents, primarily include money market funds	$ 34,300	$ 68,600